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Claims  |
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I claim:
1. A method of distributing television programmes comprising the steps of:
A) Broadcasting a programme signal which represents television programmes
interrupted by non-programme material;
B) Encrypting a signal indicating broadcast of said non-programme material;
C) Transmitting said encrypted indicating signal;
D) Receiving said programme signal and said indicating signal at a
receiving station;
E) Selectively recording the received programme signal;
F) Decrypting the received indicating signal;
G) Determining if the decrypted indicating signal indicates reception of
non-programme material;
H) Determining whether the user is authorised to remove non-programme
material;
I) If the user is authorised and the decrypted indicating signal indicates
non-programme material, pausing the selective recording of the programme
signal until such time as said indicating signal indicates cessation of
non-programme material; and
J) If the user is not authorised, continuing the selective recording of
said received programme signal.
2. A method of distributing television programmes comprising the steps of:
A) Broadcasting a programme signal of a television programme interrupted by
non-programme material;
B) Encrypting a signal indicating broadcast of said non-programme material;
C) Transmitting said encrypted indicating signal;
D) Receiving said programme signal and said indicating signal at a
receiving station;
E) Recording the received programme signal;
F) Decrypting the received indicating signal;
G) Determining if the decrypted indicating signal indicates reception of
non-programme material;
H) Testing stored data representing an amount of credit, and if the said
amount exceeds a predetermined value:
i) Pausing the recording of the programme whenever said indicating signal
indicates non-programme material, and
ii) Reducing a value of the stored data representing an amount of credit in
response to said pausing step.
3. A method of distributing television programmes according to claim 2
wherein the value of the stored data representing an amount of credit is
reduced by an amount proportional to the duration of the pausing of the
recording.
4. A method of distributing television programmes according to claim 2
wherein the value of the stored data representing an amount of credit is
reduced by subtracting a prescribed value from the stored data each time
recording is paused.
5. A television, programme distribution system comprising:
a broadcasting station including
A) Means for broadcasting a programme signal which represents television
programmes interrupted by non-programme material;
B) Means for encrypting a signal indicating broadcast of said non-programme
material; and
C) Means for transmitting said encrypted indicating signal and
a receiving station including
A) Means for receiving said programme signal and said encrypted indicating
signal;
B) Means for selectively recording said received programme signal;
C) Means for decrypting said received indicating signal;
D) Means for storing data indicating whether said receiving station is
authorised to remove non-programme material; and
E) Control means for pausing the selective recording of the received
programme signal, while said decrypted indicating signal indicates
non-programme material is being received by said means for receiving, if
the stored data indicates that the user is authorised, and for continuing
the selective recording said received signal if the stored data indicates
that the user is not authorised.
6. A television programme distribution system comprising:
a broadcasting station including
A) Means for broadcasting a programme signal of a television programme
interrupted by non-programme material;
B) Means for encrypting a signal indicating broadcast of said non-programme
material; and
C) Means for transmitting said encrypted indicating signal; and
a receiving station including
A) Means for receiving said programme signal and said encrypted indicating
signal;
B) Means for recording said received programme signal;
C) Means for decrypting said received indicating signal;
D) Means for storing data representing an amount of credit;
E) Control means for pausing the recording of the received programme
signal, while said decrypted indicating signal indicates non-programme
material is received, if said stored data representing an amount of credit
exceeds a predetermined amount; and
F) Means for reducing a value of the stored data representing an amount of
credit in response to a pausing operation initiated by said control means.
7. A television programme distribution system according to claim 6 wherein
said means for reducing a value of the stored data representing an amount
of credit in response to the pausing operation initiated by said control
means reduces said value by an amount proportional to the duration of
pausing of the recording.
8. A television programme distribution system according to claim 6 wherein
said means for reducing a value of the stored data representing an amount
of credit in response to a pausing operation initiated by said control
means reduces said value by subtracting a prescribed value from the stored
data each time recording is paused.
9. A television signal recording control system comprising:
A) A television signal receiver for receiving a television signal;
B) A recorder for recording a television signal received by said television
signal receiver;
C) An indicating signal receiver for receiving an encrypted indicating
signal;
D) A signal decryptor for decrypting said received encrypted indicating
signal;
E) Credit memory means for storing data indicating an amount of credit; and
F) A controller generating a recording pause signal for pausing said
recorder when the decrypted indicating signal indicates reception of
non-programme material by said television signal receiver and the data
stored in said credit memory means indicates that the user is authorised
to pause said recorder.
10. A television signal recording control system comprising:
A) A television signal receiver for receiving a television signal;
B) A recorder for recording a television signal received by said television
signal receiver;
C) A receiver for receiving an encrypted indicating signal;
D) A signal decryptor for decrypting said received encrypted indicating
signal;
E) Means for storing data representing an amount of credit;
F) Control means for generating a recording pause signal, for pausing said
recorder when said decrypted indicating signal indicates non-programme
material is received by said television signal receiver, if said stored
data representing an amount of credit exceeds a predetermined amount; and
G) Means for reducing a value of the stored data representing an amount of
credit in response to said recording pause signal generation.
11. A television programme recording control system according to claim 10
wherein said means for reducing a value of the stored data representing an
amount of credit in response to said recording pause signal generation
reduces said value by an amount proportional to the duration of pausing of
recording.
12. A television programme recording control system according to claim 10
wherein said means for reducing a value of the stored data representing an
amount of credit in response to said recording pause signal generation
reduces said value by subtracting a prescribed value from the stored data
each time recording is paused.
13. A method of distributing television programmes comprising the steps of:
A) Broadcasting a programme signal which represents television programmes
interrupted by non-programme material;
B) Encrypting a signal indicating broadcast of said non-programme material;
C) Transmitting said encrypted indicating signal;
D) Receiving said programme signal and said indicating signal at a
receiving station;
E) Selectively displaying a program responsive to the received programme
signal;
F) Decrypting the received indicating signal;
G) Determining if the decrypted indicating signal indicates reception of
non-programme material;
H) Determining whether the user is authorised to remove non-programme
material; and
I) If the user is authorised and the decrypted indicating signal indicates
non-programme material, disabling the selective display of the programme
until such time as the decrypted indicating signal indicates cessation of
non-programme material; and
J) If the user is not authorised, continuing the selective display of said
programme responsive to said received signal.
14. A method of distributing television programmes comprising the steps of:
A) Broadcasting a programme signal of a television programme interrupted by
non-programme material;
B) Encrypting a signal indicating broadcast of said non-programme material;
C) Transmitting said encrypted indicating signal;
D) Receiving said programme signal and said indicating signal at a
receiving station;
E) Displaying a programme responsive to the received programme signal;
F) Decrypting the received indicating signal;
G) Determining if the decrypted indicating signal indicates reception of
non-programme material;
H) Testing stored data representing an amount of credit, and if said amount
exceeds a pre-determined value:
i) Disabling display of the programme whenever said decrypted indicating
signal indicates non-programme material, and
ii) Reducing a value of the stored data representing an amount of credit in
response to said disabling step.
15. A method of distributing television programmes according to claim 14
wherein the value of the stored data representing an amount of credit is
reduced by an amount proportional to the duration of disabling of display.
16. A method of distributing television programmes according to claim 14
wherein the value of the stored data representing an amount of credit is
reduced by subtracting a prescribed value from the stored data each time
display is disabled.
17. A television programme distribution system comprising:
a broadcasting station including
A) Means for broadcasting a programme signal which represent television
programmes interrupted by non-programme material;
B) Means for encrypting a signal indicating broadcast of said non-programme
material; and
C) Means for transmitting said encrypted indicating signal; and
a receiving station including
A) Means for receiving said programme signal and said encrypted indicating
signal;
B) Means for selectively displaying a programme responsive to said received
programme signal;
C) Means for decrypting said received indicating signal;
D) Means for storing data indicating whether said receiving station is
authorised to remove non-programme material; and
E) Control means for disabling the selective display of the programme,
while said decrypted indicating signal indicates non-programme material is
received, if the stored data indicates that the user is authorised, and
for causing the selective display of the programme if the stored data
indicates that the user is not authorised.
18. A television programme distribution system comprising:
a broadcasting station including
A) Means for broadcasting a programme signal of a television programme
interrupted by non-programme material;
B) Means for encrypting a signal indicating broadcast of said non-programme
material; and
C) Means for transmitting said encrypted indicating signal; and
a receiving station including
A) Means for receiving said programme signal and said encrypted indicating
signal;
B) Means for displaying a programme responsive to said received programme
signal;
C) Means for decrypting said received indicating signal;
D) means for storing data representing an amount of credit;
E) Control means for disabling display of the programme, while said
decrypted indicating signal indicates non-programme material is received,
if said stored data amount of credit exceeds a predetermined amount; and
F) Means for reducing a value of the stored data representing an amount of
credit in response to said disabling operation initiated by said control
means.
19. A television programme distribution system according to claim 18
wherein said means for reducing a value of the stored data representing an
amount of credit in response to said disabling operation initiated by said
control means reduces said value by an amount proportional to the duration
of disabling of display.
20. A television programme distribution system according to claim 18
wherein said means for reducing a value of the stored data representing an
amount of credit in response to said disabling operation initiated by said
control means reduces said value by subtracting a prescribed value from
the stored data each time display is disabled.
21. A television programme display control system for controlling the
display for a received television programme signal on a display, said
system comprising:
A) A receiver for receiving an encrypted indicating signal;
B) A signal decryptor for decrypting said encrypted indicating signal;
C) Credit memory means for indicating an amount of credit; and
D) A controller for disabling the display of the received signal while the
decrypted indicating signal indicates reception of non-programme material
and the data stored in said credit memory means indicates that the user is
authorised to disable said display.
22. A television programme display control for controlling the display of
received television programme signals, said control comprising:
A) A receiver for receiving an encrypted indicating signal;
B) A signal decryptor for decrypting said encrypted indicating signal;
C) Means for storing data representing an amount of credit;
D) Control means for generating a display disabling signal for disabling
display of said received signals, while said indicating signal indicates
non-programme material in said received programme signals, if said stored
data representing an amount of credit exceeds a predetermined amount; and
E) Means for reducing a value of the stored data representing an amount of
credit in response to the disabling operation initiated by said control
means.
23. A television programme display control system according to claim 22
wherein said means for reducing a value of the stored data representing an
amount of credit in response to said disabling operation initiated by said
control means reduces said value by an amount proportional to the duration
of disabling of display.
24. A television programme display control system according to claim 22
wherein said means for reducing a value of the stored data representing an
amount of credit in response to said disabling reduces said value by
subtracting a prescribed value from the stored data each time display is
disabled,
25. The method of claim 1, wherein step J) comprises a step of, if the user
is not authorised and said decrypted indicating signal indicates
non-programme material, continuing to record said programme signal.
26. The method of claim 13, wherein step J) comprises a step of, if the
user is not authorised and said decrypted indicating signal indicates
non-programme material, continuing to display said programme responsive to
said received signal.
27. The system of claim 5 wherein said control means is for causing the
selective recording of the programme signal if the stored data indicates
that the user is not authorised and the decrypted indicating signal
indicates that non-programme material is being received.
28. The system of claim 17, wherein said control means is for causing the
selective display of the programme signal if the stored data indicates
that the user is not authorised and the decrypted indicating signal
indicates that non-programme material is being received.
29. The method of claim 1, wherein step J) comprises a step of, if the user
is not authorised and said decrypted indicating signal indicates programme
material, continuing to record said programme responsive to said received
signal.
30. The method of claim 13, wherein step J) comprises a step of, if the
user is not authorised and said decrypted indicating signal indicates
programme material, continuing to display said programme responsive to
said received signal.
31. The system of claim 5 wherein said control means is for causing the
selective recording of the programme signal if the stored data indicates
that the user is not authorised and the decrypted indicating signal
indicates that programme material is being received.
32. The system of claim 17, wherein said control means is for causing the
selective display of the programme signal if the stored data indicates
that the user is not authorised and the decrypted indicating signal
indicates that programme material is being received.
33. A system according to any one of claims 5-12, 27 or 31 and further
comprising memory means for recording the time and date at which the
recording is paused and the channel of a broadcast which is recorded.
34. A system according to any one of claims 17-24, 28 or 32 and further
comprising memory means recording the time and date at which the display
is disabled and the channel of a broadcast which is recorded.
35. A method as in any one of claims 1-4, 13-16, 29, 30, 33 or 34 further
comprising the step of transmitting decoy signals, which are similar to
said indicating signal, but which do not indicate non-programme material.
36. A method as in any one claims 1-4, 13-16, 29, 30, 33 or 34 wherein:
A) The encrypting step comprises the step of transmitting decoy signals,
which are similar to said indicating signal, but which do not indicate
non-programme material, said decoy signals being transmitted at times
determined by the value of an encryption key; and
B) The decrypting step comprises the step of identifying said decoy signals
according to the value of said encryption key. |
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Claims |
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Description |
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TECHNICAL FIELD
The present invention relates to methods of, and apparatus for,
distributing and viewing television programmes and for recording
television programmes for later replay.
BACKGROUND ART
In recent years it has become common for consumers of television broadcasts
to make use of video recording devices (commonly known as videocassette
recorders or VCRs) to make recordings of television programmes for their
own use. One of the most common uses of the domestic VCR is to record a
television programme which is being broadcast at a time when it is
inconvenient for the householder to watch television, or at a time when
the householder is occupied watching another desired programme on a
different channel. The programme is recorded without necessarily being
viewed at the time of recording, being replayed for viewing at a more
convenient time. This process is commonly called time-shifted viewing.
One limitation of the prior-art time-shifted viewing method is that many
programmes are broadcast with interruptions, such as non-programmes
material, which may detract from the viewer's enjoyment. Non-programme
material includes commercial messages, half-time breaks at sporting
fixtures, editorial commentary during movies, station identifications and
other material not essential to the programme. Interruptions of this
nature are one significant reason why alternative methods are often chosen
for viewing movies in particular, such as rental of pre-recorded
interruption-free movies, or subscription television services which
provide interruption free movies for a fee.
These methods also suffer limitations. Rental movies incur the
inconvenience of having to physically collect the tape from a video
library and return it after viewing, are costly compared to recording
off-air, and can only be viewed over the relatively short period of time
for which the tape is rented. Subscription services are generally of the
pay-per-view type, in which the viewer pays a fee for each movie viewed,
or time-based subscription, where the user pays a periodical fee for
access to the service for a prescribed time, during which it can be
utilised as much as desired. Both these types of subscription service
require a complex and expensive distribution infrastructure and are
expensive to operate, resulting in high cost to the consumer. One major
problem with subscription television services is piracy, that is, the
utilisation of free-to-air or cable signals by people who are not
subscribers. Piracy is a cause of considerable financial loss to service
providers, and much effort has been devoted to securing subscription or
pay-per-view services against such abuse. The primary scheme for
preventing piracy is to encrypt broadcasts in such a way as to render the
signals unwatchable except with the aid of decoders available only to
legitimate viewers. It is now also commonplace for such decoders to be
equipped with control means which enable the service provider to enable or
disable decoding from a central office, providing means of ensuring that
individual subscribers cannot continue to use their decoders unless they
have paid for the service, for example by monthly subscription. A further
well-known extension of the system is the pay-per-view arrangement,
whereby the charge for the service is based on usage. One charging method
for pay-per-view involves issuing each user a certain number of credits in
the form of data stored in the decoder. A predetermined number of these
credits are consumed each time the user selects a programme to be decoded,
and when all credits are consumed, the decoder ceases to function and the
user must purchase further credits. For convenience credits can be issued
by transmitting appropriate data to the decoder over the air or cable.
One limitation of such subscription services is that the equipment required
to deliver programmes, encrypt and decode the programme signals, and
manage the charging system is complex and expensive.
A further limitation of subscription services is that because many viewers
prefer to watch programmes including interruptions rather than pay for
viewing in cash, the demand for subscription services is not universal and
hence both commercial and commercial-free systems must co-exist, with
associated duplication of expensive resources.
A further difficulty for service providers which arises from the use of
VCRs for time-shifted viewing of commercial television broadcasts is that
users often use the fast-forward facility of a VCR to skip quickly through
commercial messages on replay. This process, called "zipping", is of great
concern to advertisers, who are paying to have their commercials broadcast
at a rate based on the number of viewers. Because it is impossible to know
how many viewers are zipping commercials, advertisers are often
incorrectly charged.
The presence of non-programme material is also a cause of annoyance to many
television viewers watching the programme as it is broadcast. A number of
schemes have been proposed for eliminating unwanted material, in
particular commercials, from television programmes being recorded or
viewed. One approach uses an indicating signal transmitted from the same
source as the television programme. An example of this scheme is apparatus
manufactured by Logica Communications and Electronic Systems, London,
known as an Advertisement Display Control Unit (ADCU). This equipment is
intended for use with cable television systems for the purpose of
eliminating advertisements in certain countries, where they are not
permitted. Advertisements are indicated by a prescribed signal inserted
into one line of the vertical interval of the television signal. On
detection of this signal at a cable head end, the ADCU interrupts
distribution of the transmission to viewers' homes, and substitutes a page
of teletext vision, until such time as the advertisement is finished as
indicated by the appropriate signal. While this scheme is effective for
the purpose of controlling commercials on a country-by-country basis, it
is designed to allow control of commercial-deletion from the point of
origin of the broadcast, and does not allow individual viewers to choose
whether or not they receive the commercials. Although it would be possible
to adapt the system for domestic use, it would not be successful because
broadcasters would lose considerable advertising revenue since it can be
expected that many viewers would disable advertisements even in countries
where television advertising is permitted. Without the cooperation of the
broadcasters, who are required to transmit the signal indicating the
presence of advertisements, this system can not work. Another scheme for
eliminating unwanted material, which does not suffer this particular
limitation, is described by Von Kohorn in U.S. Pat. No. 4,520,404.
According to this method, a monitoring station is provided where a person
watches programmes received off-air and activates a transmitter which
sends command signals indicating the presence of non-programme material to
viewers' homes at the appropriate moments. The command signals are
received separately from the television programme being viewed or recorded
and utilised by a controller adapted to black out television display or
pause recording while unwanted material is being received. Although this
scheme is effective in achieving the object of allowing viewers to edit
out unwanted material from broadcasts, it suffers from a number of
shortcomings. In particular, the system does not provide a method of
charging users on a basis of usage, nor is it possible to ascertain how
many viewers are editing out commercials, since so long as the viewer is
equipped with the editing system, it can be used as much or as little as
desired.
The present invention is directed towards providing new and useful
alternatives to known television programme distribution, editing and
viewing arrangements.
According to prior-art television distribution systems, programmes are
either encrypted and broadcast without commercials, in which case viewers
must pay to be able to receive and decode these programmes, or programmes
are transmitted in a form anyone can receive and view without payment, in
which case the programmes are generally interrupted by commercials.
According to this invention, programmes are transmitted unencrypted and
with commercials and a signal indicating the presence of non-programme
material is also transmitted, viewers being provided with controllers
which cause elimination of unwanted material from viewing or recording. In
this respect, the system is similar to that of Von Kohorn's U.S. Pat. No.
4,520,404. However the present invention further provides a system for
enabling the elimination of unwanted material only while pre-purchased
credit remains. Alternatively, the indicating signal can be embedded in
the broadcast signal, for example in the manner of the Logica ADCU. In
this case also, the present invention provides for revenue-control.
The present invention, therefore provides a significant benefit over the
prior art in that members of the viewing public can choose whether they
wish to view programmes, for example movies, free of charge but with
interruptions, or to view programmes free of interruptions, but to pay a
charge. One significant functional difference between the well known
pay-per-view system and that of this invention is that whereas in the case
of pay-per-view the viewer pays to receive or record a particular
programme, in the case of this invention the viewer pays in order not to
see or record certain material. This is of benefit to the viewer, in that
the additional service is offered but does not interfere with the
provision of the conventional commercial service, as the broadcast need
not be encrypted since it is intended that anyone be able to receive it
without charge. The invention is advantageous also to the broadcaster, as
it allows provision of an additional service, and source of additional
revenue, not unlike pay-per-view service, at very little capital or
running cost. The invention is also beneficial to the advertisers who
purchase advertising time during broadcasts as it allows the audience not
watching the commercials to be more accurately assessed, so that
advertisers can have greater confidence that the audience for which they
are paying is being delivered. The advertisers also benefit in that the
invention makes it less attractive to manually zap recordings, that is,
remove commercials by manually pausing the VCR when recording a programme,
or fast-forwarding through commercials when replaying.
DISCLOSURE OF INVENTION
According to a first aspect of the present invention there is provided a
method of distributing television programmes comprising the steps of
broadcasting a television signal for a programme interrupted by
non-programme material, encrypting a signal indicating broadcast of
non-programme material, transmitting said encrypted indicating signal,
receiving both signals at a receiving station, recording the received
programme, testing stored data indicating whether the user has been
previously authorised to use the invention at that time and, if the user
has been previously authorised to use the invention at that time,
decrypting the received indicating signal, and if the decrypted indicating
signal indicates reception of non-programmne material, pausing the
recording of the programme until such time as an indicating signal
indicating cessation of non-programme material is received. The term
"previously authorised" as used herein refers to payment for, or
commitment to pay for, use of the service, such payment or commitment
having been made prior to use.
According to a further extension of the invention, the invention further
comprises a method of charging for the removal of unwanted programme
material, namely storing data representative of an amount of credit
purchased by the user, disabling the recording control function of the
invention if the credit falls below a predetermined amount, and reducing
the amount of credit stored by an amount proportional to the duration of
unwanted programme material removed. In another aspect, the credit amount
is reduced by a predetermined amount each time recording is paused, so
that charging is based on the number of times unwanted material is
eliminated, rather than the cumulative duration of eliminated material.
In other aspects, the invention also comprises the indicating signal
receiver and controller used in carrying out the methods described above.
In another aspect, the present invention provides television programme
distribution means comprising means for broadcasting a television signal
for a programme interrupted by non-programme material, means for
encrypting in a secure manner a signal indicating broadcast of
non-programme material, means for transmitting said encrypted indicating
signal, means for receiving both signals at a receiving station, means for
recording the received programme, means for decrypting the received
indicating signal, control means adapted to determine whether the user has
been previously authorised to use the invention at that time and, if this
condition is satisfied, and if the decrypted indicating signal indicates
reception of non-programme material, to pause the recording of the
programme until such time as an indicating signal indicating cessation of
non-programme material is received. Other aspects of the invention further
provide means for charging for elimination of unwanted programme material,
according to the methods of charging per use or charging for duration
described above.
In accordance with another useful extension, any of the foregoing aspects
of the invention can be beneficially adapted to cause display of a
television programme to be disabled when unwanted material is being
broadcast, utilising indicating signal, encryption, authorisation and
charging schemes as described in relation to control of recording of
programmes.
A further beneficial embodiment of the invention includes means for
recording and reporting usage of the invention in terms of time, date and
channel being received, this information being available to the service
providers for gathering statistics which are of use to the service
providers, broadcasters, advertisers and others.
BRIEF DESCRIPTION OF DRAWINGS
Some embodiments of the invention will now be described, by way of example
only, with reference to the drawings in which:
FIG. 1 is a block diagram of an embodiment in which the indicating signal
is embedded into the programme broadcast;
FIG. 2 is a block diagram of an embodiment in which the indicating signal
is received from a source other than the programme broadcast; and
FIG. 3 is a schematic diagram illustrating the information flows within the
invention.
MODE FOR CARRYING OUT THE INVENTION
Referring to FIG. 1, broadcast signals are received by antenna 1, and
passed via VCR 3 to television receiver 2, where they can be viewed in the
conventional manner. The video output of VCR 3 includes a composite video
signal, including in its vertical blanking interval a signal indicating
the type of material being received. In this embodiment, the indicating
signal is embedded into the broadcast vertical interval of the
synchronising signal by the broadcaster. The indicating signal may be
present continuously, or only during certain times, as desired by the
broadcaster. Typically, the indicating signal would be present during
broadcast of movies or drama, and would indicate whether the current
broadcast is programme or non-programme material. The indicating signal is
transmitted repeatedly and frequently, a minimum of once per second in
this embodiment, so that proper operation can be ensured from the moment
of enabling the system at a particular user's station. It may also be
desirable to transmit the indicating signal about one second in advance of
changes in type, to allow for response time of recording equipment.
The indicating signal is also encrypted to prevent utilisation by
unauthorised persons. The output of VCR 3 is fed to data extractor 4,
which senses the appropriate line-of the vertical interval and extracts
the signal located therein, presenting the extracted signal to decryptor 6
and controller 7. Decryptor 6 applies a key from keystore 8 to the
extracted data, resulting in a decrypted signal being fed to controller 7.
As well as signals indicating programme or non-programme material, the
signals embedded in the broadcast, and hence presented to controller 7
from decryptor 6, include signals used for controlling credit and
security, hereinafter referred to as accounting signals. The credit
control function is provided as follows. Usage of the service is provided
on a basis of payment per time unit of non-programme elimination. The user
purchases a given duration of service, for example 100 minutes, by placing
an order with the service provider (in this case the broadcaster). This is
conveniently performed by phoning a central office, requesting the desired
amount of service, quoting a subscriber number, and authorising charging
to a credit card. The central office then transmits, via the vertical
interval signalling means, an accounting signal which includes a serial
number unique to that subscriber, a signal indicating the number of
minutes credit to be granted, and a sequence number. Controller 7, on
recognising these signals, compares the address signal to the address
stored in address store 14, and if the address matches, increments credit
store 9 by this number of minutes. The security function operates by
allowing the service provider to change the decryption key in the keystore
periodically to provide further security. Accounting signals used, in this
embodiment are also encrypted.
The encryption and decryption technique employed in this invention can be
any of the many well-known techniques commonly used for controlling access
to data or programmes by authorised subscribers only. The scheme utilised
by this embodiment of the invention is described in detail below, with
reference to FIG. 3.
Referring again to FIG. 1, to use the invention for eliminating unwanted
non-programme material from a given recording, the user enables the device
using keyboard 12. Keyboard 12 in this embodiment is a pushbutton switch
array which sends data to controller 7. Some choices can be made according
to prompts issued by controller 7 via display 13. Choices can include
selection of a mode whereby suppression of unwanted material only takes
place during the desired programme, and not immediately preceding or after
it. This is useful in conserving credit units in cases where the user does
not mind the non-programme material surrounding the recorded programme.
Timer functions can also be offered, for starting and stopping the
controlling action at preset times of day.
Once enabled, controller 7 monitors signals from decryptor 6, and on
recognition of a non-programme material signal, causes infrared
transmitter 10 to send a PAUSE code to VCR 3, which has been previously
set into RECORD mode, either by the user or by the generation of suitable
infrared signals by this invention. Recording is thereby suspended for the
duration of non-programme material, after which a resumption signal is
detected by controller 7 and a signal suitable for causing resumption of
recording is transmitted to VCR 3 by infrared transmitter 10. Controller 7
also measures the duration of the non-programme material eliminated, and
decrements credit store 9 by a corresponding amount. If credit store 9
reaches zero, further operation of the elimination function is inhibited,
and a suitable message is transmitted to the user via display 13. The user
must then purchase further credit as described above. This method of
decrementing credit store 9 is chosen for convenience only, and other
methods can be used with good results. For example, controller 7 can be
arranged to decrement credit store 9 by a fixed amount each time
non-programme material is selected and recording is suspended, so that
consumption of credit is a function of number of suspensions rather than
duration of suspensions.
Display 13 in this embodiment is a liquid crystal display mounted on the
enclosure of the apparatus of the invention. It is also used to indicate,
on request via keyboard 12, credit units remaining. In some cases, the
service provider might transmit labelling information along with the other
indicating signals, such labelling signals indicating the title of
programmes as they are broadcast. These labels can be displayed by display
13, or used to control VCR 3 so that recording can be initiated or
terminated automatically on commencement or completion of a programme,
specified by name by the user. Display 13 can be other display means, such
as a character generator producing messages visible on the television
screen.
Status detector 5 of this embodiment is provided to enable controller 7 to
sense the operational status of VCR 3. Status detector 5 comprises sensing
circuitry adapted to sense presence of video signal, and optionally also
to determine whether the signal indicates that VCR 3 is in play mode,
pause mode or fast spooling mode. The detected status is used by
controller 7 to ensure that control signals transmitted to VCR 3 are the
correct ones for achieving the desired control functions. For example, in
the case of some VCRs, a PAUSE signal received will have different effects
depending on the current status of the VCR transport. The absence of video
signal can also be used by controller 7 as an indication that the VCR is
not operating, so that an OPERATE command can be sent to it, or a warning
signal can be generated to alert the user.
Referring now to FIG. 2, a block diagram of a second embodiment of the
invention is shown. This embodiment is similar to the first embodiment,
except that the indicating signals which in the first embodiment are
received along with the broadcast programme are in this case received from
a source separate from the broadcast. This separate source is typically a
radio transmitter operated by a party other than the broadcaster of the
programme. In this case, signals indicating advent of non-programme
material are generated by monitoring broadcasts and transmitting
appropriate signals as changes in the broadcast occur. In this embodiment
indicating signals are received by indicating signal receiver 4, via
antenna 15, which may for convenience be the same antenna as antenna 1,
and fed to decryptor 6 and controller 7. The indicating signals are
similar to those of the first embodiment described above, except that
additional data must be included to indicate to which one of many
available channels of broadcast a particular indicating signal
corresponds. Controller 7 uses this extra data to ensure that PAUSE
signals are only generated when non-programme material indication is
received corresponding to the channel of the broadcast being recorded, and
that other indicating signals are ignored. The relevant channel can be
requested from the user, who enters it via keyboard 12, or the channel can
be automatically determined by status detector 5, using one of the well
known techniques for this purpose. Operation of this embodiment is
otherwise the same as in the case of the first embodiment.
The security functions of these embodiments of the invention will now be
described with reference to FIG. 3.
As seen in FIG. 3, transmitter 309 is the means for transmitting the
indicating signals and accounting signals of the invention. Indicating
data 306 is a realtime signal indicating the nature of the programme
currently being broadcast from a broadcasting station (not shown). This
signal typically indicates whether the current broadcast is programme
material or non-programme material, although more detailed information can
also be provided, such as the name of the current programme. Indicating
data 306 is fed to one input of function generator F2, which receiv | | |
