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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to an input/output device for use in
various machines, such as facsimile machines, for inputting and outputting
required information, and, in particular, to an input/output device having
a reading section for optically reading information and a recording
section for recording information on a recording medium.
2. Description of the Prior Art
A facsimile machine is well known in the art and is widely used. A
facsimile machine has dual functions: a reading function for optically
reading image information from an original document so as to transmit it
to a receiver at a remote location and a recording function for recording
information received from a transmitter at a remote location on a
recording medium. For this purpose, it is required that the facsimile
machine be provided with a path for transporting an original document to
be read and another path for transporting a recording medium to be
recorded. The prior art facsimile machine is typically provided with two
separate transporting paths, one for original documents and the other for
recording paper, which hinders to make the machine compact in size. In
addition, the prior art facsimile machine is typically provided with a
paper sensor for sensing the presence or absence of, the remaining amount
of and/or the trailing edge of recording paper. Such a paper sensor is a
separate element normally disposed between a paper feeding section and a
recording section. The provision of such a separate paper sensor also
hinders the making of the machine smaller in size and lower at cost.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided an input/output
device having a reading section and a recording section, which shares a
common path for transporting an original document and a recording medium,
whereby the reading section is located upstream of said recording section
with respect to the direction of transportation of said original document
or recording medium through said common path. Preferably, the input/output
device has an integrated structure. In one embodiment, the input/output
device includes a head unit which includes a supporting plate in which the
reading and recording sections are integrally provided. The input/output
device also includes a common feed roller which may be pressed against the
head unit, so that either an original document or recording paper is
transported along the common path as sandwiched between the head unit and
the common feed roller. The relative positional relation between the head
unit and the common feed roller is varied under control such that either
one of the reading and recording sections is selectively brought into an
operative position.
The reading section typically includes a plurality of light-emitting
elements, such as LEDs, and a plurality of light-receiving elements, such
as photodiodes, each arranged in the form of a linear array extending in
the direction transverse to the direction of transportation as the common
transportation path. Since an original document and recording paper are
selectively transported through the common transportation path, the
reading section can be used not only for reading the original document,
but also for detecting various conditions of recording paper in
transportation.
It is therefore a primary object of the present invention to obviate the
disadvantages of the prior art as described above and to provide an
improved input/output device.
Another object of the present invention is to provide an input/output
device suitable for use in a facsimile machine and the like, thereby
allowing to make the machine compact in size.
A further object of the present invention is to provide an input/output
device compact in size, reliable and fast in operation, and easy in
maintenance.
A still further object of the present invention is to provide an
input/output device simple in structure and low at cost, and, thus,
suitable for applications to various machines, including facsimile
machines.
Other objects, advantages and novel features of the present invention will
become apparent from the following detailed description of the invention
when considered in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration showing an input output device
constructed in accordance with one embodiment of the present invention
suitable for application to a facsimile machine;
FIGS. 2a through 2c are schematic illustrations showing changes in the
relative positional relation between the reading and recording sections;
FIG. 3 is a schematic illustration showing a head unit suitable for use in
the structure shown in FIG. 1;
FIGS. 4a and 4b are schematic illustrations showing examples of a mark
indicating the remaining amount of a roll of recording paper for use in
the structure shown in FIG. 1;
FIGS. 5a through 5c are schematic illustrations useful for explaining the
detection function provided by the reading section 8 in the structure
shown in FIG. 1;
FIGS. 6a through 6c are flow and timing charts which are useful for
understanding some of the detection functions provided by the structure
shown in FIG. 1;
FIGS. 7a and 7b are illustrations useful for understanding the paper skew
detecting function provided by the structure shown in FIG. 1;
FIGS. 8a and 8b are illustrations useful for understanding the paper width
detecting function provided by the structure shown in FIG. 1;
FIGS. 9a and 9b are illustrations useful for understanding the roughened
paper edge detecting function provided by the structure shown in FIG. 1;
FIGS. 10 through 26 are schematic illustrations showing various specific
examples of the reading section 8a of the structure shown in FIG. 1;
FIGS. 27 through 29 are schematic illustrations which are useful for
explaining an embodiment in which a portion having a different reflecting
index is provided in the common feed roller 7 in the structure shown in
FIG. 1;
FIG. 30 is a schematic illustration which is useful for understanding the
reading operation by the reading section 8 of the structure shown in FIG.
1;
FIGS. 31 through 36 are schematic illustrations which are useful for
understanding the importance between the relative length relationship
between the reading and recording sections 8 and 9 in the structure shown
in FIG. 1; and
FIGS. 37 through 41 are schematic illustrations which are useful for
understanding a control system for use in the structure shown in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 1, there is schematically shown an input/output
device constructed in the form of an integrated reader/recorder in
accordance with one embodiment of the present invention. This illustrated
structure is particularly suitable for use as a part of a facsimile
machine. As shown, the illustrated device includes a table 1 for holding
thereon a stack of original documents to be read. At the forward end of
the table 3 is disposed a document separation roller 2 and a document
separating member 3, which together serve to separate and feed the
bottommost document from the stack of original document. That is, with the
provision of the separating roller 2 and member 3, original documents
placed on the table 1 in the form of a stack are insured to be fed one by
one. Below the table 1 is disposed a roll 4 of recording paper, which is
unwound to supply recording paper 4a to be used for recording information
thereon. Although not shown specifically, it should be understood that the
roll 4 is rotatably supported so as to allow to supply recording paper 4a
as being unwound therefrom. A supply roller 5 is provided at a location
close to the unwinding position of the roll 4, and a tension roller 6 is
also provided as pressed against the supply roller 5, so that the
recording paper 4a unwound from the roll 4 is sandwiched between these two
rollers 5 and 6. Typically, the supply roller 5 is driven to rotate
intermittently, so that the recording paper 4a may be unwound from the
roll 4 and supplied to a recording section as will be described more in
detail later.
Also provided is a common feed roller 7 which is driven to rotate
intermittently for moving either an original document or recording paper.
Opposite to the common feed roller 7 is disposed an integrated head unit
10 which is integrally provided with a reading section 8 and a recording
section as spaced apart over a distance l in the direction of
transportation. As will be described more in detail later, it should be
noted that the reading section 8 is located upstream of the recording
section 9 with respect to the direction of transportation. The common feed
roller 7 is preferably pressed against the head unit 10 and the contact
surface between the common feed roller 7 and the head unit 10 defines a
common path for transporting either an original document or recording
paper selectively. Described more in detail, the common transportation
path is defined between the common feed roller 7 and the head unit 10, and
a first feed path for feeding an original document to the common
transportation path extends from the separator roller 2 to the common
transportation path and a second feed path for feeding recording paper 4a
to the common transportation path extends from the supply roller 5 to the
common transportation path. Thus, the first and second feed paths merge
into the common transportation path defined between the common feed roller
7 and the head unit 10.
A cutter unit including a stationary blade 11 and a rotary blade 12 is
disposed downstream of the common feed roller 7 with respect to the
direction of transportation along the common transportation path.
Furthermore, a discharging roller 13 is disposed downstream of the cutter
unit with respect to the direction of transportation along the common
transportation path. A tension roller 14 is provided as pressed against
the discharging roller 13. A tray 15 is provided to receive thereon an
original document or recording paper discharged out of the common
transposrtation path by the discharging roller 13 in cooperation with the
tension roller 14. Thus, original documents and/or cut sheets of recording
paper 4a are stacked on the tray 15.
In operation, during a read mode of operation, original documents placed on
the table 1 in the form of a stack are separated and fed one by one
through the cooperation between the separator roller 2 and the separating
member 3 and each of the original documents is transported through the
common transportation path by the common feed roller 7. And, while the
original document is being transported by the common feed roller 7, it is
optically read by the reading section 8, and, then, the original document
is discharged out onto the tray 15 by means of the discharging roller 13.
During read mode, the cutter unit including the stationary and rotary
blades 11 and 12 are normally held inoperative. It is to be noted that
when read mode is selected, the relative positional relation between the
common feed roller 7 and the head unit 10 is so set that the common feed
roller 7 is directly opposite to and, preferably, in contact with the
reading section 8 of the head unit 10. In the case where the home position
of the common feed roller 7 is set at the center between the reading and
recording sections 8 and 9, then the feed roller 7 is moved to the right
over a distance of 1/2 so as to establish a read mode condition. It should
be noted, however, that the head unit 10 may be moved to the left over a
distance corresponding to 1/2 or both of the common feed roller 7 and the
head unit 10 may be moved so as to bring the common feed roller 7 and the
reading section 8 in an opposed relation.
On the other hand, when a recording mode of operation is selected, either
the common feed roller 7 is moved to the left or the head unit 10 is moved
to the left over a distance of 1/2, or both of the common feed roller 7
and the head unit 10 are moved to bring the common feed roller 7 directly
opposite to the recording section 9 of the head unit 10. Preferably, the
common feed roller 7 is brought into pressure contact with the recording
section 9 of the head unit 10 when recording mode is selected. The
recording section 9 may have any desired structure, but, in one
embodiment, it includes a plurality of heat-producing elements, such as
electrical resistors, arranged in the form of a linear array extending in
the direction transverse to the direction of transportation of recording
paper. When the recording section 9 has such a thermal printhead
structure, the recording paper 4a must be of heat-sensitive nature or
heat-sensitive tape must be used between the recording section 9 and the
paper 4a if the paper 4a is not of the heat-sensitive type.
During recording mode, the separator roller 2 is held inoperative, and the
supply roller 5 is driven so that the recording paper 4a is unwound from
the roll 4 and fed into the common transportation path defined between the
common feed roller 7 and the head unit 10 or the recording section 9 of
the head unit 10 in the present mode. When the leading edge of the
recording paper 4a has reached the contact between the common feed roller
7 and the head unit 10, the recording paper 4a is caused to move along the
common feed path while being pressed against the recording section 9 to
which an image signal to be recorded is supplied. When the recording paper
4a has advanced over a predetermined distance beyond the cutter unit
comprised of the stationary and rotary blades 11 and 12, the cutter unit
is activated so that the recording paper 4a is severed to a desired
length, and, then, this cut sheet of recording paper 4a is discharged out
onto the tray 15 by means of the discharging roller 13. After cutting, the
common feed roller 7 and the supply roller 5 are driven to rotate in the
reverse direction until the leading edge of the recording paper 4a of the
roll 4 has been moved back to a position between the rollers 5 and 7,
i.e., in the second feed path defined between the rollers 5 and 7. Thus,
the recording paper 4a would not interfere with the operation of
transporting an original document when the read mode of operation is
selected next time.
As described above, in the input/output device of the present invention,
provision is made of the head unit 10 integrally provided with the reading
and recording sections 8 and 9 and of the common feed roller 7. The
relative positional relation between the common feed roller 7 and the head
unit 10 is varied to establish either read mode or recording mode
selectively. In the illustrated embodiment, both of the reading and
recording sections 8 and 9 are provided at a flat bottom surface of the
head unit 10, so that it is only necessary to move at least one of the
common transportation roller 7 and the head unit 10 relative to each other
at least in the horizontal direction. Thus, both of the reading and
recording sections 8 and 9 share the common transportation path which is
commonly used for transporting either an original document or recording
paper 4a selectively. Besides, the common transportation roller 7 is
commonly used for transporting either an original document or recording
paper. As a result, many elements are commonly used both for reading and
recording operations in the illustrated structure, which then allows to
make the entire structure compact in size at lower cost.
FIG. 2a shows an embodiment which is so structured that the common
transportation roller 7 may be moved horizontally with respect to the
reading and recording sections 8 and 9 provided in the head unit 10. In
this embodiment, the common feed roller 7 is rotatably supported at a top
end of a lever 18 which has its bottom end pivottally supported by a pivot
pin 19. The lever 18 is operatively coupled to a solenoid 16 and is
normally biased toward the left by means of a spring 17. Thus, the common
feed roller 7 is normally biased to take a position indicated by the solid
line where the common feed roller 7 is pressed against the recording
section 9, thereby establishing the recording mode . On the other hand,
when the solenoid 16 is activated, the lever 18 is moved closer to the
solenoid until the common feed roller comes to be located at a position
indicated by the one-dotted line where the common feed roller 7 is pressed
against the reading section 8 to establish the read mode. In the
illustrated embodiment, the head unit 10 integrally provided with the
reading and recording sections 8 and 9 spaced apart from each other is
pivotally supported by a pivot pint 10a at one end and has its opposite
end operatively coupled to another solenoid 20. In addition, a spring 21
is provided and its one end is connected to a fixed position, such as a
frame (not shown) of the input/output device, and its other end connected
to the head unit 10, so that the head unit 10 is normally pressed against
the common feed roller 7 under the force of the spring 21. In this
embodiment, the solenoid 20 is temporarily activated to move the head unit
10 away from the common feed roller 7 while the common feed roller 7 moves
between the two positions: reading and recording positions.
The solenoid 20 can serve another function when it is provided as
illustrated. That is, when the leading edge of an original document or
recording paper 4a comes around, the solenoid 20 is temporarily activated
to move the head unit 10 separated away from the common feed roller 7,
thereby insuring that the original document of recording paper 4a can be
properly inserted between the common feed roller 7 and the head unit 10.
It is to be noted, however, that the solenoid 20 may be discarded, if
desired.
FIG. 2b shows an embodiment of transmitting a rotational force to the
common feed roller 7. In the illustrated embodiment, rotational power is
first transmitted from a motor (not shown) to a pulley 27 fixedly mounted
on a first shaft 27 by means of a belt 26. A gear 29 is also fixedly
mounted on the first shaft 29 and it is in mesh with another gear 31 which
is fixedly mounted on a second shaft 30, on which the common feed roller 7
is also fixedly mounted. Since the gears 29 and 30 remain meshed
irrespective of the pivotal motion of the common feed roller 7 by the
lever 18, the common feed roller 7 may be driven to rotate in any desired
direction. Also shown in FIG. 2b is a pair of auxiliary gears 32 and 33
which are provided at respective fixed positions, and the gear 31 comes to
be in mesh with the auxiliary gear 32 when the common feed roller 7 is
located at the reading position, i.e., in contact with the reading section
8 of the head unit 10, whereas, the gear 31 comes to be in mesh with the
auxiliary gear 33 when the common feed roller 7 is located at the
recording position to be in contact with the recording section 9 of the
head unit 10. Thus, preferably, the auxiliary gear 32 is operatively
coupled to the separator roller 2 through a power transmission train (not
shown), and the other auxiliary gear 33 is operatively coupled to the
supply roller 5 through another power transmission train (not shown).
FIG. 2c shows an embodiment in which the head unit 10 provided with the
reading and recording sections 8 and 9 is movable and the common feed
roller 7 is fixed in position. In this embodiment, the head unit 10 has
its left end operatively coupled to the solenoid 20 and its left end
operatively coupled to a further solenoid 22 through a lever 24 which has
its bottom end pivotally connected to the right end of the head unit 10
and its top end pivotally supported by a pivot pin 25. The head unit 10
has its bottom surface provided with the reading and recording sections 8
and 9 pressed against the common feed roller 7 under the force of the
spring 21, and the head unit 10 is also normally biased toward the left by
means of a spring 23. As a result, the head unit 10 is normally biased to
take the position indicated by the solid line, in which case the reading
section 8 of the head unit 10 is in contact with the common feed roller 7.
On the other hand, when the solenoid 22 is activated, the head unit 10 is
moved to the right to take the position indicated by the one-dotted line,
so that the recording section 9 comes to be in contact with the common
feed roller 7.
In the above-described embodiments, use is made of solenoids and pivots.
However, it should be noted that various other mechanisms, such as cams,
may also be used to carry out required relative motion between the common
feed roller 7 and the head unit 10.
FIG. 3 schematically illustrates the basic structure of the head unit 10
suitable for use in the structure shown in FIG. 1. As shown, the head unit
10 is generally comprised of a flat plate on which the reading and
recording sections 8 and 9 are fixedly mounted. A read driver circuit 34
and a recorder driver circuit 35 are also fixedly mounted on the flat
plate. Thus, the head unit 10 in this embodiment has an integral structure
having both reading and recording functions. It is to be noted that, in
the illustrated embodiment, the flat plate has a substantially flat bottom
surface and the reading and recording sections 8 and 9 are provided at the
bottom surface of the plate as spaced apart from each other over a
predetermined distance.
It should be noted that in accordance with one feature of the present
invention, the integrated head unit 10 is so arranged that its reading
section 8 is locted upstream of the recording section 9 with respect to
the direction of transportation defined in the common transportation path.
With this arrangement, the reading section 8 can be used not only for
optically reading an original document, but also for detecting
predetermined conditions of recording paper, such as detection of the
leading edge and/or trailing edge, when cut in the form of a sheet, and
detection of the remaining amount of the recording paper. In addition, the
reading section 8 also can be used to detect whether the recording paper
being transported is skewed, to detect the size of the recording paper
being transported, and to detect the length of time expended for
transporting the recording paper.
FIGS. 4a and 4b show two examples how the remaining amount of recording
paper 4a may be detected using the reading section 8 of the present head
unit 10. In the case of FIG. 4a, a set of characters "40 m" 27 indicating
the amount of remaining recording paper is written on the recording paper
at the center by a predetermined color, such as yellow, which does not
interfere with the color used for recording information on the recording
paper 4a. On the other hand, in the case of FIG. 4b, a marker 28 is
provided along one side of the recording paper 4a. Such characters 27 or
marker 28 may be optically read by the reading section 8 of the head unit
10 during recording mode of operation.
As briefly described above, the reading section 8 of the head unit 10 of
the present input/output device can be used to determine predetermined
conditions regarding the recording paper 4a during the recording mode.
This aspect of the present invention will now be described in detail
below. It will be assumed in the following description that the reading
section 8 of the head unit 10 is of the intimate contact type so that an
object to be read by the reading section 8 must be brought into close
contact therewith. Thus, an object to be read is preferably brought into
pressure contact with the reading section 8. In general, in an optical
reading unit of the intimate contact type, an associated feed roller
typically has a peripheral surface which is white in color or a similar
color, as described in Japanese Patent Laid-open Pub. No. 58-73275. In the
present embodiment, the common feed roller 7 is assumed to have a
peripheral surface which has a white or similar color.
As shown in FIG. 5a, the reading section 8 of the head unit 10 typically
includes a light-emitting or light source subsection and a light-receiving
or sensor subsection 8b. The light-emitting subsection 8a typically
includes a plurality of light-emitting elements, such as light-emitting
diodes, arranged in the form of a linear array, and the light-receiving
subsection 8b typically includes a plurality of light-receiving elements,
such as photodiodes, arranged in the form of a linear array. Thus, when
the leading edge of the recording paper 4a approaches the reading section
8 as shown in FIG. 5a, the light emitted from the light-emitting
subsection 8a comes to be reflected more into the light-receiving
subsection 8b. Thus, the amount of light received by the light-receiving
subsection 8b differs depending on whether the recording paper 4a is
present in the vicinity of the reading section 8 or not, and this fact may
be utilized to detect the presence or absence or the leading edge or
trailing edge of the recording paper 4a. FIG. 5a shows the case of
detecting the leading edge of the recording paper 4a. On the other hand,
FIG. 5b shows the case in which the surface of the recording paper 4a is
optically read by the reading section 8, so that any sign or mark,
indicating, for example, the remaining amount, on the recording paper 4a
may be read. FIG. 5c is a view when taken as indicated by A--A40 in FIG.
5b. As shown in FIG. 5c, due to optical scanning of the light-receiving
subsection 8b in the main direction or widthwise direction of the
recording paper 4a, the side edges of the recording paper 4a may be
optically determined. That is, an output signal of the reading section 8
is an analog signal whose level varies depending on the intensity of the
light received by the light-receiving subsection 8b. Since the light
received by that portion of the light-receiving subsection 8b which is
opposite to the recording paper 4a is higher in intensity than the rest,
when the output signal of the reading section 8 is subjected to
thresholding operation, that portion of the light-receiving subsection 8b
which corresponds to the recording paper 4a may be indicated to be white
or one of the two binary states and the rest may be indicated to be black
or the other binary state. In the preferred embodiment, a microprocessor
(not shown) is provided and the data collected by the light-receiving
subsection 8b is supplied to the microprocessor for determining the
current conditions of the recording paper 4a.
(a) Monitoring Processing Time for Recording Paper
The leading edge of the recording paper 4a is initially located at a
predetermined position between the supply roller 5 and the common feed
roller 7 in the structure shown in FIG. 1. Upon initiation of the
recording mode of operation, the recording paper 4a is caused to move at a
predetermined speed over a predetermined amount. In this case, however, if
the reading section 8 has failed to detect the leading edge of the
recording paper 4a within a predetermined time period, it is determined
that some abnormal condition has occurred in the transportation system so
that detection of jamming is activated, as shown in the flow chart of FIG.
6a. On the other hand, even if the leading edge of the recording paper 4a
has been properly detected, and, thus, the recording operation by the
recording section 9 has initiated, if the recording operation has
continued beyond a predetermined time period, it is determined that some
abnormal condition has occurred so that the occurrence of abnormality is
indicated. In this manner, a maximum recording time period is previously
set and when this limit has been exceeded, it is determined that some
faulty operation has occurred. In this case, such a condition may be
determined by monitoring the amount of the recording paper 4a transported
or the time required for transporting the recording paper 4a. As shown in
FIG. 6c, after detection of the leading edge of the recording paper 4a, if
the recording operation has continued beyond a predetermined maximum time
period, then it is determined that the operation is faulty.
(b) Detecting the Conditions of Recording Paper
The presence or absence of recording paper 4a at a predetermined position
may be effected, for example, by detecting the leading and trailing edges
of the recording paper 4a. As shown in FIG. 6c, the time period T
indicates a time period during which the recording paper 4a is present at
the recording station. The degree of skew of recording paper 4a may be
detected by the reading section 8 as shown in FIGS. 7a and 7b. If the
recording paper 4a moves past the reading section 8 as transported in the
direction indicated by the arrow with a skew as indicated in FIG. 7a, a
detection signal obtained from the reading section 8 varies in a timed
sequence as shown in FIG. 7b. It is apparent that the presence or degree
of skew of the recording paper 4a may be detected by appropriately
processing these signals.
(c) Detecting the Size of Recording Paper
One example of detecting the size of the recording paper 4a using the
reading section 8 of the head unit 10 is illustrated in FIGS. 8a and 8b.
As is obvious from these figures, the size or width of the recording paper
4a being transported may be determined by obtaining and processing a pair
of side edges signals which are produced by the reading section 8
corresponding in position to the side edges of the recording paper 4a
moving past the reading section 8. On the other hand, if the leading or
trailing edge of the recording paper 4a is irregular or roughened, this
fact may be detected by sporadically appearing signals along the
lengthwise direction of the reading section 8 as shown in FIG. 9b.
(d) Reading of Marker on Recording Paper
As shown in FIGS. 4a and 4b, a marker indicating the approaching of the end
of or the remaining amount of the recording paper 4a may be read by the
reading section 8 of the head unit 10. Upon reading of such a marker, an
alarm signal may be produced to give a warning to the operator. If the
present input/output device is incorporated in a facsimile machine, this
alarm signal may be transmitted to another facsimile machine in
communication to apprise of the fact that the recording paper 4a is
running out.
As described above, in accordance with the above-described structure of the
present invention, during the recording mode of operation, the reading
section 8 of the head unit 10 can be used to monitor various conditions of
the recording paper 4a. That is, the reading section 8 may be used not
only for reading an original document during the reading mode of
operation, but also for monitoring various conditions of the recording
paper 4a during the recording mode of operation.
When the reading section 8 is to be used for monitoring the recording paper
4a during the recording mode of operation, the reading accuracy or
required resolution is less strict than the case of reading an original
document. That is, to read an original document optically requires the
resolution in the order of 8 lines/mm; on the other hand, less accurate
resolutions are sufficient for using the reading section 8 for monitoring
various conditions of the recording paper 4a under transportation. This is
because when reading an original document during the reading mode, an
image signal obtained by the reading section 8 is required to faithfully
represent the nature of the information contained in the original
document. On the other hand, when the reading section 8 is to be used for
monitoring of the recording paper 4a during the recording mode, the nature
of the information to be detected is very simple and thus high resolution
is usually not required. It is to be noted that, in the present invention,
an output signal obtained from the reading section 8 is subjected to
thresholding operation during either the reading mode or recording mode,
so that the output signal is always converted to binary data for further
processing.
Under the circumstances, in accordance with one aspect of the present
invention, it is so structured that a plurality of light-emitting elements
provided in the light-emitting subsection 8a are selectively activated. In
the preferred embodiment, during the reading mode, all of the plurality of
light-emitting elements are activated; on the other hand, during the
recording mode, the light-emitting elements are activated only
selectively. For this purpose, an interface should be provided to
selectively activate the light-emitting elements depending upon the mode
of operation.
FIGS. 10a and 10b show one example of the light-emitting subsection 8a. As
shown in FIG. 10a, the light-emitting subsection 8a is comprised of an N
plurality of light-emitting blocks arranged in the form of a linear array.
In the present embodiment, as shown in FIG. 10b, each of the
light-emitting blocks includes an n plurality of light-emitting diodes
connected in series. All of the light-emitting blocks are connected in
parallel and each of the light-emitting blocks has its one end connected
to a supply voltage V.sub.cc through a resistor R1 and its other end
connected to the collector of an NPN transistor Q1 which has its emitter
connected to ground and its base connected to receive an activation
signal. With this structure, when the activation signal is applied to the
base of the transistor Q1 to have it turned on, power is applied to all of
the light-emitting diodes at the same time.
FIGS. 11a and 11b show an example of the reading section 8 which may be
advantageously applied to the input/output device shown in FIG. 1. In the
illustrated example, the reading section 8 includes a sensor or
light-receiving subsection 8b comprised of an X plurality of photodiodes
arranged in the form of a linear array and a pair of light source or
light-emitting subsections 8a and 8a' each disposed on each side of the
sensor subsection 8b in a side-by-side arrangement. As shown in FIG. 11b,
these subsections 8a, 8a' and 8b are fixedly mounted on a flat plate 8c
constituting part of the head unit 10. In the illustrated embodiment, a
filling material is also provided to fill the gaps between the subsections
8a, 8a' and 8b to provide a relatively smooth surface. This is
advantageous in the contact type reading unit as in the present embodiment
because an object to be read must be brought into sliding contact with the
light-receiving subsection 8b.
Now, for detecting the presence or absence of the recording paper 4a at a
predetermined location, it is only necessary to detect part of the
recording paper 4a. Thus, in the case of detecting the presence or absence
of the recording paper 4a at the reading section 8 during the recording
mode, it is only necessary to activate at least one particular block among
those light-emitting blocks which are located between the side edges of
the recording paper 4a. FIG. 12 illustrates the case when only the central
light-emitting block e is activated for the purpose of detecting the
presence or absence of the recording paper 4a at the reading section 8 of
the head unit 10.
In the case of detecting the width of the recording paper 4a moving past
the reading section 8 during the recording mode, if two different sizes of
recording paper, e.g., A4 and B4, are selectively usable, then it is only
necessary to activate, for example, the central light-emitting block e and
another light-emitting block k which is located outside of A4 size but
inside of B4 size. With activation of these two light-emitting blocks e
and k, the size of the recording paper 4a under transportation may be
determined to be either A4 or B4.
On the other hand, as shown in FIG. 14a, the skew of the recording paper 4a
may be detected by activating at least two light-emitting blocks, c and k
in the illustrated example, which are located within the width of the
recording paper 4a. In the present example, the left edge of the recording
paper 4a is first detected by the light-emitting block c, there is
produced a signal output from this block at a certain point in time. And,
then, the right edge of the recording paper 4a is also detected. Thus, the
skew of the recording paper 4a may be detected by observing a temporal
difference in the production of an output signal from each of the selected
light-emitting blocks c and k. The degree of this temporal difference also
indicated the degree of skew.
In addition, in order to detect such a mark as shown in FIG. 4a or 4b,
which indicates the remaining amount of the recording paper 4a in the roll
4, it is only necessary to activate those light-emitting blocks which
correspond in position to such a mark.
FIG. 15 shows an embodiment of the light-emitting subsection 8a which is so
structured that light-emitting blocks c, e and k may be independently
selected for activation. That is, these light-emitting blocks are
connected to respective terminals A through C which in turn are connected
to an interface circuit. Each of the light-emitting blocks has its one end
connected to a power supply terminal D and its other end connected to a
common terminal E. In one example, during the reading mode of operation,
the terminal E is selected so that all of the light-emitting blocks are
activated at the same time. On the other hand, during the recording mode
of operation, terminal B is selected if desired to detect the presence or
absence of the recording paper 4a as shown in FIG. 7a, terminals B and C
are selected if desired to detect the size (width) of the recording paper
4a as shown in FIG. | | |
