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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a television telephone apparatus.
2. Description of the Related Art
According to the recent development of highly information-oriented society,
there is an increasing demand for communication media by which a vast
amount of various types of information are transmitted fast. To fulfill
such a demand in Japan, the "analog telephone band still picture video
communication system" was established in 1988 as a standard communication
system to allow for communication of a monochromatic image between parties
over a communication line. The standards was amended in 1989 so that a
color image as well as a monochromatic image can be exchanged. Various
television (TV) telephone apparatuses which conform to those standards
have been developed so far. The TV telephone apparatuses are expected to
become popular because of their advantages that visual information can be
sent to cover voice-based information or explanation which is often
difficult to consume or visualize and that telephone communication is
possible while watching the caller's or receiver's expressions.
TV telephone apparatuses are classified by types of communication networks
to be linked and the types of image and voice transmission functions. For
example, some TV telephone apparatuses are connected to an analog public
telephone line to transmit a monochromatic still picture or a color still
picture, or to transmit a color dynamic image. The still-picture TV
telephone apparatus, which is connected to an analog public telephone line
to send a monochromatic still picture, employs a system for directly
transmitting image data without compression. For monochromatic image data
of 64 gray scales (6 bits) with one screen consisting of 100.times.160
pixels, for example, data of about 100.times.160.times.6=96000 bits (about
11.7 Kbytes) has been transmitted at a transfer rate of about 8740 bps
(bit per second). This takes about 11 seconds to send one screen of image
data.
Image data carries a large amount of information so that direct processing
of image data is not practical in view of memory capacity, communication
speed and so forth. As a solution, there has been proposed a color
dynamic-image TV telephone apparatus which compresses image data and voice
data to about 1/20 to 1/100before transmission to thereby ensure
transmission and reception of a dynamic image at a rate of two to ten
frames per second using an analog telephone band.
As the compressed transmission of image data will transfer a considerable
amount of data, a slight transmission delay will not affect the
progression of telephone communication so much. Therefore, variable length
coding (e.g., variable length coding system which conforms to H. 261 of
the CCITT (Comite Consultatif International Telegraphique et Telephonique)
regulations) is typically employed.
In compressed transmission of voice data, digitalization of voice data can
compress the length of the average produced bits. Generally speaking, if
entropy compression (e.g., Hoffman coding) which does not guarantee the
maximum bit length is adapted for voice signals, a large transmission
delay of voice signals occurs when voice signals are converted to a long
bit length by the entropy compression. This would greatly affect the
progression of telephone communication. In this respect, voice data is
encoded with a fixed bit length before transmission.
TV telephone apparatuses, which are connected to such an analog
communication network, have a communication function to transmit/receive
image data and voice data in multiplexed form. A communication protocol
corresponding to the communication networks to be linked and a coding
system for image data and voice data, which are affixed to a
protocol-based communication signal for transmission/reception, are
specified for each type of communication network by the CCITT regulations,
etc.
The conventional TV telephone apparatuses generally have an integrated
telephone function and therefore become inevitably large.
Liquid crystal (LC) televisions recently become popular and are installed
on vehicles or used to watch TV programs, such as sport programs.
Pocket-size LC televisions have been developed so that users can watch TV
programs any time on their ways to offices or on business trips.
Telephones are often used outside offices, but they of course permit only
voice communication.
In the conventional TV telephone apparatus which compresses image data and
voice data before transmission, a camera as an image input/output unit, a
CRT (Cathode Ray Tube) as an image display unit, and a telephone as a
voice input/output unit are designed as one integrated unit to transmit
compressed data. It is therefore difficult to provide compact and light
portable TV telephone apparatuses. Further, the existing telephones cannot
be used in such a TV telephone apparatus. In other words, the convention
TV telephone apparatuses have been designed as non-portable so that, once
the apparatuses are installed, it is hard to move them around and use them
at any desired location.
The image quality of liquid crystal display (LCD) devices has been improved
and are expected as a replacement of CRT. The use of the LCD device will
contribute to a reduction of consumed power and will ensure compact and
light TV telephone apparatuses. The telephone function may be designed
separable from the TV telephone apparatuses so that those apparatuses
become more compact and lighter. In addition, it is unreasonable that a
person, if carrying an LC television that can show a dynamic image, is
restricted to transmit only voices at time of using a telephone.
The conventional TV telephone apparatuses, even if designed compact and
light, still require a troublesome connection of various input/output
(I/O) terminals, a power terminal, etc. every time they are used as TV
telephones. In particular, in a case that a TV telephone apparatus whose
portability is important is likely to be carried out often, it is quite
troublesome since the user should disconnect the I/O terminals, etc. when
carrying the apparatus out, and should connect them again when using it.
In addition, it is necessary to charge the battery of the TV telephone
apparatus occasionally, and connect a full-charged or additional battery
for a long time transmission/reception. This makes the conventional TV
telephone apparatus further troublesome. As various I/O terminals, a power
terminal, etc. should be connected upon every usage, persons who are not
familiar with such connection will not easily make such connections. In
other words, the conventional TV telephone apparatus is not user friendly.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a TV
telephone apparatus, which is compact and light to be portable and will
ensure transmission/reception of high-quality images without requiring
connection of every one of terminals, such as various I/O terminals and a
power terminal.
According to an aspect of the present invention, there is provided a TV
telephone system comprising a TV telephone apparatus including image
pickup means, display means and an input/output port to connect to another
apparatus; and a station including a modulation/demodulation section to
connect to a telephone line and an input/output port to connect to the TV
telephone apparatus, whereby when the TV telephone apparatus is connected
to the station, an image is transmitted and received over a telephone line
using the image pickup means and display means of the TV telephone
apparatus.
According to another aspect of the present invention, there is provided a
TV telephone system that comprises a TV telephone apparatus, which
includes a modulation/demodulation section to connect to a telephone line,
image pickup means, display means, an input/output port to connect to
another apparatus and a power input terminal; and a station, which
includes an input/output port to connect to the TV telephone apparatus and
a power output terminal whereby the station is electrically connected to
the TV telephone apparatus, and supplies power to the TV telephone
apparatus. When TV telephone apparatus is connected to the station or a
telephone line, an image is transmitted and received over a telephone line
using the image pickup means and display means of the TV telephone
apparatus.
According to a still another aspect of the present invention, there is
provided a TV telephone system that comprises a TV telephone apparatus,
which includes image pickup means, display means, a
modulation/demodulation section to connect to a telephone line, and an
input/output port to connect to another apparatus; and a station, which
includes image pickup means, display means, a modulation/demodulation
section to connect to a telephone line, an input/output port to connect to
the TV telephone apparatus and a connecting terminal to connect to a
telephone, whereby the station is electrically connected to the TV
telephone apparatus and the telephone. When TV telephone apparatus is
connected to the station or a telephone line, an image is transmitted and
received over a telephone line using the image pickup means and display
means of the TV telephone apparatus, and the station executes transmission
and reception of an image over the telephone line using the image pickup
means and display means of the station.
Additional objects and advantages of the invention will be set forth in the
description which follows, and in part will be obvious from the
description, or may be learned by practice of the invention. The objects
and advantages of the invention may be realized and obtained by means of
the instrumentalities and combinations particularly pointed out in the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part
of the specification, illustrate presently preferred embodiments of the
invention, and together with the general description given above and the
detailed description of the preferred embodiments given below, serve to
explain the principles of the invention.
First Embodiment
FIG. 1 is a diagram showing the connection of a TV telephone apparatus
equipped with a TV telephone station;
FIG. 2 is a perspective view of the TV telephone apparatus equipped with
the TV telephone station in FIG. 1;
FIG. 3 is a perspective view of the TV telephone station in FIG. 2;
FIG. 4 is a perspective view showing the TV telephone station in FIG. 2
from the rear side;
FIG. 5 is an enlarged view for explaining the structure of the essential
portion in FIG. 4;
FIG. 6 is a block diagram showing the general structure of the TV telephone
apparatus;
FIG. 7 is a block diagram showing the general structure of the TV telephone
station;
FIG. 8 is a diagram showing the structure of one frame of a multiplexed
code;
FIG. 9 is a flowchart illustrating the operation of the TV telephone
apparatus and the TV telephone station;
FIG. 10 is a flowchart illustrating the operation of the TV telephone
apparatus and the TV telephone station;
FIG. 11 is a flowchart illustrating the transmission operation of the TV
telephone apparatus and the TV telephone station;
FIG. 12 is a flowchart illustrating the reception operation of the TV
telephone apparatus and the TV telephone station; and
FIG. 13 is a diagram showing a modification of the first embodiment of the
present invention.
Second Embodiment
FIG. 14 is a diagram showing the connection of a pocket type telephone
apparatus equipped with a TV telephone station;
FIG. 15 is a perspective view of the pocket type telephone apparatus
equipped with the TV telephone station in FIG. 14; and
FIG. 16 is a diagram showing the pocket type telephone apparatus mounted on
the TV telephone station.
Third Embodiment
FIG. 17 is a diagram showing the connection of a TV telephone apparatus
equipped with a TV telephone station;
FIG. 18 is a perspective view of the TV telephone apparatus equipped with
the TV telephone station in FIG. 17;
FIG. 19 is a perspective view showing the TV telephone apparatus in FIG. 18
from the rear side;
FIG. 20 is a perspective view showing the TV telephone station in FIG. 18
from the rear side;
FIG. 21 is a block diagram showing the general structure of the TV
telephone apparatus; and
FIG. 22 is a block diagram showing the general structure of the TV
telephone station.
Fourth Embodiment
FIG. 23 is a diagram showing the connection of a pocket type telephone
apparatus equipped with a TV telephone station;
FIG. 24 is a perspective view of the pocket type telephone apparatus
equipped with the TV telephone station in FIG. 23;
FIG. 25 is a diagram showing the pocket type telephone apparatus in FIG.
23;
FIG. 26 is a diagram showing the power-supply connection between the pocket
type telephone apparatus and the TV telephone station; and
FIG. 27 is a diagram showing a modification of the fourth embodiment.
Fifth Embodiment
FIG. 28 is a diagram showing the connection of a TV telephone system
equipped with detachable parent and child TV telephone apparatuses;
FIG. 29 is a diagram showing the connection of the parent TV telephone
apparatus to an external unit;
FIG. 30 is a perspective view of the child TV telephone apparatus;
FIG. 31 Is a perspective view showing the child TV telephone apparatus from
the rear side;
FIG. 32 is a perspective view of the parent TV telephone apparatus;
FIG. 33 is a diagram showing the child telephone apparatus mounted on the
parent TV telephone apparatus;
FIG. 34 is a block diagram showing the general structure of the child TV
telephone apparatus; and
FIG. 35 is a block diagram showing the general structure of the parent TV
telephone apparatus.
Sixth Embodiment
FIG. 36 is a perspective view of a child TV telephone apparatus with an
integrated pager function; and
FIG. 37 is a block diagram showing the general structure of the child TV
telephone apparatus with the integrated pager function.
Seventh Embodiment
FIG. 38 is a diagram showing the connection of an electronic camera
equipped with an image station;
FIG. 39 is a perspective view of the electronic camera equipped with the
image station in FIG. 38;
FIG. 40 is a block diagram showing the general structure of the electronic
camera;
FIG. 41 is a block diagram showing the general structure of the image
station; and
FIG. 42 is a block diagram of a card seal printer section of the image
station.
Eighth Embodiment
FIG. 43 is a diagram showing the connection of a TV telephone apparatus
equipped with a TV telephone station;
FIG. 44 is a perspective view of the TV telephone apparatus in FIG. 43;
FIG. 45 is a diagram showing the connection between the TV telephone
station and the TV telephone apparatus;
FIG. 46 is a block diagram showing the general structure of the TV
telephone apparatus;
FIG. 47 is a block diagram showing the general structure of the TV
telephone station;
FIG. 48 is a flowchart for explaining an auto-answering process of the TV
telephone station and TV telephone apparatus;
FIG. 49 is a flowchart for explaining an auto-answering process of the TV
telephone station and TV telephone apparatus; and
FIG. 50 is a flowchart for explaining an auto-answering process of the TV
telephone station and TV telephone apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will now be described below with
reference to the accompanying drawings.
First Embodiment
A TV telephone apparatus according to the first embodiment of the present
invention will be described with reference to FIGS. 1 through 13. In the
first embodiment, a telephone function is incorporated on the station
side.
First, the structure of the first embodiment will be discussed with
reference to FIGS. 1 through 8. The following description will be given
with reference to the case where an ordinary analog telephone subscriber
line is used as a communication line.
FIG. 1 is a diagram for explaining the connection of a TV telephone
apparatus equipped with a TV telephone station. Referring to FIG. 1, the
TV telephone apparatus equipped with a TV telephone station according to
the first embodiment comprises a portable TV telephone apparatus 100 and a
TV telephone station 150 having an integrated telephone function. The TV
telephone apparatus 100 is designed to transmit and receive high-quality
images, uses a liquid crystal display (LCD) device to become compact and
light, and is detachably mounted to the TV telephone station 150. The TV
telephone station 150 is connected between a telephone line and a
telephone to transmit and receive image data and voice data over the
telephone line. The TV telephone station 150 where the TV telephone
apparatus 100 is to be mounted, is connected between a modular jack type
socket 201 and a telephone 202, and has a LINE I/O terminal 1L to connect
to an analog public telephone line and a TEL I/O terminal 1T to connect to
the telephone 202. The socket 201 and the LINE I/O terminal 1L, or the TEL
I/O terminal 1T and the telephone 202 are connected by a modular cable 204
that has modular plugs 203 at both ends.
FIG. 2 is a perspective view of the TV telephone apparatus equipped with
the TV telephone station in FIG. 1, and FIG. 3 is a perspective view of
the TV telephone station in FIG. 2. In FIG. 2, the TV telephone apparatus
100 has a case 101 which has a horizontally elongated, narrow rectangular
shape. A camera section 102 is mounted on the top left portion of the case
101, and is supported at the top portion of the case 101 to be rotatable
180 degrees in the forward and backward direction. Therefore, the angle of
the lens 102a of the camera 102 can be adjusted within the range of 180
degrees in the forward and backward direction of the case 101, so that an
object image can be picked up within 180 degrees in that direction. A
liquid crystal display (LCD) section 103 and a key input section 104 are
provided at the front of the case 101. The LCD section 103 has a DD
(Display Driver) 34 and LCD (Liquid Crystal Display) 35, and the key input
section 104 includes a plurality of key switches 10 that an operator uses
to select and instruct various processes for the TV telephone apparatus
100, as will be described later with reference to FIG. 6. The LCD section
103 is a TFT (Thin Film Transistor) type active matrix LCD device having a
screen size of 1.4 inches, and is equipped with a high-resolution color
LCD panel having a total of 220.times.279=61380 pixels of which every
three pixels corresponding to three primary colors R (Red), G (Green) and
B (Blue) are arranged in a delta form. Power switch 105 is provided on one
side of the case 101 to turn on or off the main power supply of the TV
telephone apparatus 100.
Provided at the top of the case 101 are a volume dial 106 for adjusting the
volume of voice, an earphone terminal 107, a selector switch 108 for
switching one mode to another, a tuning button 109, and a power indicter
110 which indicates the ON/OFF state of the main power supply. Provided at
the bottom of the case 101 an I/O port (not shown) to connect to an I/O
port terminal 152 provided at a recessed portion 151a of a case 151 of the
TV telephone station 150, which will be discussed later. The horizontally
long shape of the case 101 improves the stability of the TV telephone
apparatus 100 when placed down or mounted on the station 150. The volume
dial 106 is used to control the volume of a sound coming through an
earphone. The tuning button 109 is used to increase or decrease the tuning
frequency. The earphone terminal 107 is where an earphone that serves as a
wire antenna is coupled, and also serves as an antenna terminal.
The TV telephone station 150, when connected with the compact, light and
portable TV telephone apparatus 100, expands the functions of the TV
telephone apparatus 100. The TV telephone station 150 of this embodiment
incorporates a MODEM (Modulation and DEModulation) and NCU (Network
Control Unit) which achieve a telephone function. When connected between
the modular jack type socket 201 and the telephone 202, the TV telephone
station 150 transmit and receive image data and voice data by the
integrated telephone function.
In FIG. 2, the case 151 of the TV telephone station 150 has a rectangular
shape wider and deeper than the case 101 of the TV telephone apparatus
100, and is short as compared with its width and depth so that the TV
telephone apparatus 100 can stably stand upright when mounted. The recess
151a is formed at the top center of the case 151 to surely position the TV
telephone apparatus 100 at a predetermined position, as shown in FIG. 3.
The TV telephone apparatus 100 will be mounted on the TV telephone station
150 by placing the bottom of the TV telephone apparatus 100 on the recess
151 at the top center of the case 151. The aforementioned I/O port
terminal 152 is provided at the top center of the recessed portion 151a of
the case 151 and connects to the I/O port terminal (not shown) provided at
the bottom of the TV telephone apparatus 100. When the TV telephone
apparatus 100 is mounted on the recess 151a of the case 151 of the TV
telephone station 150, their I/O ports engage with each other to ensure
data exchange between the apparatus 100 and the station 150.
As shown in FIGS. 2 and 3, provided at the front of the case 151 are a
power switch 153 to turn on or off the TV telephone station 150, an LED
154 for indicating a communication state, and a dip switch 155 for setting
the communication environments of a MODEM 30 and NCU 31, which will be
discussed later. The dip switch 155 is closed by a cover 156 provided at
the front of the case 151 after setting is completed.
FIG. 4 is a perspective view showing the back of the TV telephone station
in FIG. 2, and FIG. 5 is an enlarged view for explaining the structure of
the essential portion in FIG. 4. Provided at the back of the case 151 are
the aforementioned LINE I/O terminal IL and TEL I/O terminal 1T, an I/O
port 157 for data input/output via a predetermined cable, a pin terminal
158 for receiving and sending a video signal, pin terminals 159 and 160
for receiving and sending a voice signal, a VHF antenna terminal 161 for
receiving a VHF signal, a UHF antenna terminal 162 for receiving a UHF
signal, an S terminal 163 for receiving and sending a video signal, and a
power cord 164, as shown in FIG. 4. As shown in FIG. 5 which presents an
enlarged illustration of the essential portion, the TV telephone station
150 intervenes between the socket 201 (FIG. 1) and the telephone 202 and
is connected between the socket 201 and the telephone 202 by the modular
cables 204 having the modular plugs 203 connected to the LINE I/O terminal
1L and the socket 201 and connected to the TEL I/O terminal 1T and the
telephone 202.
In this case, since the TV telephone station 150 is designed on the premise
that it is left in a house, an office or the like, the TV telephone
station 150 may be left always connected to the socket (telephone line)
201 and the telephone 202. With this connection, even data exchange with
the portable TV telephone apparatus 100 can be accomplished by connecting
this TV telephone apparatus 100 to a telephone line or like outside the
house.
FIG. 6 presents a block diagram showing the schematic structure of the TV
telephone apparatus 100 shown in FIG. 2. In FIG. 6, the TV telephone
apparatus 100 comprises the camera section 102, the LCD section 103, a
controller 11, an image processor 12, and a voice processor 13. The key
input section 104, controller 11, image processor 12, voice processor 13
and an I/O port 50 are connected together by a bus 15.
The key input section 104, as shown in FIG. 2, has a plurality of key
switches 10 that the operator uses to select and instruct various
processes for the TV telephone apparatus 100.
The controller 11 comprises a CPU (Central Processing Unit) 16, RAM (Random
Access Memory) 17, and ROM (Read Only Memory) 18. The I/O port 50 is an
I/O mechanism which receives necessary data from outside and sends out
data to an external device. The bus 15 is a signal line to connect the key
switches 10, controller 11, image processor 12 and voice processor 13
together, and includes an address bus for specifying an address and a data
bus for transferring data. The CPU 16 outputs various control signals over
the bus 15 to the individual sections of the TV telephone apparatus 100 to
control those sections, and runs a communication control program according
to the type of the communication line to be linked. When the TV telephone
apparatus 100 is mounted on the TV telephone station 150, the TV telephone
station 150 receives multiplexed image data and voice data from the linked
TV telephone apparatus of the other party, demodulates those data in a
MODEM section 14 (see FIG. 7) and sends the demodulated data to the CPU
16. The CPU 16 separates the demodulated image data and voice data from
each other, and sends compressed image data to an image
compressing/expanding circuit 19 via the bus 15 while sending compressed
voice data to a voice compressing/expanding circuit 27 via the bus 15.
Further, the CPU 16 multiplexes the compressed image data sent from the
image compressing/expending circuit 19 via the bus 15 and the compressed
voice data sent from the voice compressing/expanding circuit 27 via the
bus 15, and outputs the multiplexed image data and voice data to the MODEM
section 14 of the TV telephone station 150 via the bus 15. The RAM 17 is a
semiconductor memory for storing program data, which is used in the
programmed processing that is executed by the CPU 16, the compressed image
data and voice data, etc. The ROM 18 is a semiconductor memory for storing
the program, data, etc. which are used inside the TV telephone apparatus
100.
The image processor 12 includes the image compressing/expanding circuit 19,
a buffer memory 20, an ADC (Analog to Digital Converter) 21, a video
memories (VRAMs) 22 and 23, and a DAC (Digital to Analog Converter) 24.
The image compressing/expanding circuit 19 compresses (encodes) the image
data stored in the video memory 22 by performing DCT (Discrete Cosine
Transform), quantization and Hoffman coding every block of 8.times.8
pixels, based on a predetermined encoding system, such as JPEG (Joint
Photographic (Coding) Experts Group) algorithm according to the type of
images to be dealt with (still picture in this case), expands (decodes)
compressed image data, which has been received over a communication line
and has been demodulated by the MODEM section 14 in the TV telephone
station 150, and stores the expanded image data into the video memory 23.
The image compressing/expanding circuit 19 has a function to process image
data, sent over the communication line as a color video signal of
110.times.160 pixels in 4096 colors (12 bits) at the maximum, as a YC
signal which consists of a luminance signal (hereinafter referred to as "Y
signal") equivalent to 220.times.279 pixels and a color signal
(hereinafter referred to as "C signal") equivalent to 4096 colors. The
12-bit data of 110.times.160 pixels will be converted to 12-bit digital
image data of 220.times.279 pixels. The data compression ratio in the
image compression is about 7/100 (about 8/1000) in view of the image
quality after expansion. The buffer memory 20 temporarily stores
compressed image data coming from the image compressing/expanding circuit
19, and the compressed image data stored in this buffer memory 20 will be
read piece by piece in response to a control instruction from the CPU 16.
If the buffer memory 20 is given a sufficient memory capacity, plural
blocks of image data picked up by the camera section 102 can be stored in
compressed form, so that the TV telephone apparatus 100 may be used as an
electronic still camera. The ADC 21 converts the image signal (analog
signal) from the camera section 102 to a signal (digital signal) that can
be processed in the image processor 12, and sends the resultant signal to
the video memory 22. The video memories 22 and 23 are semiconductor VRAMs
for storing image data (digital data) from the ADC 21 or the compressed or
expanded image data (digital data) from the image compandor 19. The DAC 24
converts the image signal (digital signal) in the image data, stored in
the video memory 23, to a signal (analog signal) that can be displayed on
the LCD section 103, and sends the resultant signal to the LCD section
103. As an analog data driver is used as the data driver for an LCD 28 (to
be described later) in first embodiment, the DAC 24 is needed. If a
digital data driver is used as the data driver, however, this DAC 24
becomes unnecessary.
The voice processor 13 includes an ADC 26, the voice compandor 27, a buffer
memory 28 and a DAC 29. The ADC 26 converts the voice signal (analog
signal) which is input from the telephone 202 via the MODEM section 14,
NCU 31 and I/O port 52 of the TV telephone station 150 and the I/O port 50
of the TV telephone apparatus 100, to a signal (digital signal) that can
be processed in the voice processor 13, and sends the resultant signal to
the voice compressing/expanding circuit 27. The voice
compressing/expanding circuit 27 compresses (encodes) the input data from
the bus 15 by a predetermined encoding system, which is accomplished by
means for analyzing the digital voice data from the ADC 26 over a given
period of time according to, for example, a CELP (Code Excited Linear
Prediction) algorithm, means of synthesizing the waveforms of voice data
based on the analyzed parameters, means for calculating an error between
the input waveform and the synthesized waveform, and other necessary
means, and outputs the compressed voice data to the DAC 29. The voice
compressing/expanding circuit 27 expands (decodes) the compressed image
data, which has been received over the communication line and has been
demodulated by the MODEM section 14 in the TV telephone station 150, and
outputs the expanded image data to the DAC 29. The data compression ratio
in the voice compression is about 5/100 (about 50/1000) in view of the
voice quality after expansion. The buffer memory 28 temporarily stores
compressed voice data coming from the voice compressing/expanding circuit
27. The compressed voice data stored in the buffer memory 28 will be read
piece by piece in response to a control instruction from the CPU 16.
The camera section 102 comprises a lens 32 and a CCD (Charge Coupled
Device) 33 in FIG. 6. The lens 32 is an optical lens made of glass or
plastic, and is installed on the main body of the TV telephone apparatus
100. The CCD 33 generates an electric signal based on the intensity of
light formed by the lens 32, and outputs this electric signal (analog
signal) to the image processor 12.
The LCD section 103 includes the aforementioned DD 34 and LCD 35. Reference
numeral "36" denotes a TV tuner, reference numeral "37" is an ADC,
reference numeral "34a" is a video input terminal and reference numeral
"34b" is a video output terminal. The DD 34 drives the LCD 35 to display
an image on the LCD 35 based on the video signal input from the image
processor 12 or the video signal coming from the video input terminal 34a.
More specifically, the DD 34 converts the input video signal to an analog
video signal (analog RGB signal) of a predetermined bit with 220.times.279
pixels and outputs the analog video signal to the LCD 35. The LCD 35 is a
color LCD device having an LCD panel of TFT type which is one of active
matrix types, and displays a color video signal in 4096 colors (12 bits)
at the maximum when driven by the DD 34. As mentioned earlier, the number
of display pixels of the LCD 35 is 110.times.160.
In general, an LCD is considerably thin, and is easily made compact and
lighter, as compared with a CRT or other similar image display means.
Since the active matrix type LCD can allow the intermediate tone to be
finely controlled, can provide a higher contrast ratio and has a faster
response, as compared with a direct matrix type LCD, the active matrix
type LCD is a very effective device in the fields where multi-color
display of a high-quality image is demanded. Particularly, the active
matrix type LCD which uses three-terminal TFTs will provide a high-quality
image that matches with that of a CRT.
The TV tuner 36 receives predetermined TV broadcasting waves, and outputs
the video signals via the ADC 37 to the buffer memory 20.
The ADC 37 converts the analog video signal from the TV tuner 36 to a
digital signal.
A power supply circuit 51 has a rechargeable batter and a voltage
regulator, and regulates the supply voltage of the rechargeable battery
with the voltage regulator to supply the regulated supply voltage to the
individual sections of the TV telephone apparatus 100. Although the power
supply circuit 51 uses a rechargeable battery in the first embodiment, it
may use a non-rechargeable battery like a dry battery as well.
FIG. 7 presents a block diagram showing the schematic structure of the TV
telephone station 150 shown in FIG. 2. In FIG. 7, the TV telephone station
150 comprises the power switch 153, the LED 154, the dip switch 155, a
controller 170, the MODEM section 14 and the I/O port 52.
The dip switch 155 is used to select various processes in the TV telephone
station 50 and set the communication environments of the MODEM 30 and NCU
31.
The controller 170 comprises a CPU 171, RAM 172 and ROM 173. The CPU 171
controls the individual sections in the TV telephone station 150 and
executes a communication control program according to the type of the
communication line to be linked. When the TV telephone apparatus 100 is
mounted on the TV telephone station 150, the CPU 171 receives multiplexed
image data and voice data from the linked TV telephone apparatus of the
other party, and demodulates those data in the MODEM section 14. The CPU
171 then separates the demodulated image data and voice data from each
other, and sends compressed image data to the image compandor 19 while
sending compressed voice data to the voice compressing/expanding circuit
27. Further, the CPU 171 multiplexes the compressed image data sent from
the image compandor 19 and the compressed voice data sent from the voice
compressing/expanding circuit 27, and outputs the multiplexed image data
and voice data to the MODEM section 14. The RAM 172 is a semiconductor
memory for storing program data, which is used in the programmed
processing that is executed by the CPU 171, the voice data to be
transmitted, etc. The ROM 173 is a semiconductor memory for storing the
program, data, etc. which are used inside the TV telephone station 150.
The MODEM section 14 comprises the aforementioned MODEM 30 and NCU 31. As
mentioned earlier, "1L and "1T" are I/O terminals for the communication
line (ordinary subscriber line in this case). The I/O terminal 1L is
connected to the modular jack type socket 201 via the modular cable 204,
and the I/O terminal 1T to the telephone 202 also via the modular cable
204. The MODEM 30 and NCU 31 have a function as a modulator to convert a
sequence of digital signals output from a computer or a terminal device to
a transmission signal (analog signal) that can be transmitted over a
communication line, and a function as a demodulator to restore a
transmission signal (analog signal) received over the communication line
to a digital signal that can be translated by a computer or a terminal
device. The NCU 31 allows the use of an ordinary subscriber line as such a
communication line. This MODEM 30 has an A/D converter and a buffer
memory, and converts demodulated data to a digital signal and stores it in
the buffer memory temporarily. The CPU 16 reads the data from this buffer
memory, separates image data and voice data from each other, and sends the
image data to the image compressing/expanding circuit 19 while sending the
voice data to the voice compressing/expanding circuit 27. The MODEM 30 and
NCU 31 in the first embodiment are capable of transmitting signals at the
highest data transfer rate of 14400 bps for the analog public line. The
MODEM 30 and NCU 31 puts a video code and a voice code in one frame that
is a processing unit to thereby simultaneously transmit image data and
voice data. One screen of image data will be transmitted as an
intermittent image at a rate of one frame every three seconds.
FIG. 8 is a diagram showing the structure of one frame of a multiplexed
code. The multiplexed code constituting one frame consists of video data
of about 256 bytes (about 2048 bits), which has a video header and the
video code, and voice data of about 256 bytes (about 2048 bits), which has
a voice header and the voice code. The video code and voice code each
includes an error correction code or redundancy checking code in addition
to the video header or voice header affixed before the video code or the
voice code. The total of the actual amount of image data included in the
video code and the actual amount of voice d | | |
