JPS6390221A - Binarizing circuit for image sensor output - Google Patents

Abstract

PURPOSE:To always obtain an accurate binary signal by selecting a binary signal in a floating system or a binary signal based on a single threshold voltage in accordance with the output difference between adjacent CCD outputs of intermittently given CCD outputs. CONSTITUTION:In case of an original which is painted out in white or black and whose read output is changed in DC, the binary output is fixed to a high or low level and the accurate binary signal cannot be obtained because the output of a CCD and the output obtained by integrating it are always equal to each other. The difference between adjacent CCD outputs of intermittently given CCD outputs is detected, and the binary signal in the floating system is selected if the output difference exceeds a prescribed value, and the binary signal based on a single threshold voltage is selected if the output difference is smaller than the prescribed value. Thus, the accurate binary signal is outputted even if the read output of the original surface is changed in AC as well as DC.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image sensor output binarization circuit used in optical image data reading means.

[Prior art and its problems] Recently, ultra-compact hand-held copy machines and the like have been equipped with a technology that irradiates light from a light source onto the document surface and receives reflected light from the document surface using an image sensor, such as a COD, to read image data. Image data reading means are used.

Incidentally, it is known that the output voltage of the COD used as such an image sensor changes depending on the rate of change in contrast between white and black on the surface of the document. Therefore, for example, as shown in FIG. 7(a), image data of a document surface with a white:black ratio of 1:1 is read. The overall voltage level is higher in the latter case than in the case of reading the image data of the original surface where the white:black relationship is 5=1 as shown in FIG.

For this reason, conventionally, as a means to binarize the output of a COD, a so-called floating method has been adopted in which a binarized output is obtained by comparing the output of the COD and a floating value obtained by integrating the output of the COD. There is.

However, when such a floating method is adopted, as mentioned above, white parts and black parts appear alternately on the document surface, and if the readout output has alternating current changes, there is no problem with the answer, but if the reading output has alternating current changes, then the so-called solid white or In the case of something like solid black where the read output shows a direct current change, the output of the COD at this time and the output obtained by integrating the output of the COD are always equal, so the binarized output is rHJ or rLJ. This has the disadvantage that accurate binarized signals cannot be obtained.

[Objective of the Invention] This invention was made in view of the above circumstances, and it is possible to obtain an accurate binary signal regardless of whether the reading output of the document surface changes in an alternating current or direct current manner. The object of the present invention is to provide a binarization circuit with the power obtained.

[Summary of the Invention] The image sensor output binarization circuit according to the present invention has the following features:
An output means for outputting an intermittent image signal from an image sensor that reads data on a document surface, and a first binarization means for binarizing the image signal output by the output means based on an integral value of the image signal. , second 21a converting means for converting the image signal outputted by the outputting means into 2Wi based on a single threshold voltage, detecting a difference between adjacent image signals outputted by the outputting means; It has an output difference detection means, and when the output difference detected by the detection means exceeds a predetermined value, the binarized signal of the first 21ia converting means is selected, and when the output difference is less than the predetermined value, the binarized signal is selected. The binarized signal of the second binarizing means is selected.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

This embodiment shows an example in which the present invention is applied to a handy copy machine. FIG. 1 shows the external configuration of a handy copy machine embodying the present invention. In the figure, 1 is the main body of the handy copy machine, for example, the width is 7011,
It has a size of about 30 cm in thickness and 160 cm in height, and has an effective reading width of 40 mm, an effective print width of 40 mm, and a reading memory length of 2 mm.
00 full, a read dot density of 8 dots/u+, and a print dot density of 8 dots/m-. However, the handheld copy machine main body 1 has a tip portion,
That is, a head section HA for reading and printing is provided at the lower end in the figure. The head portion HA is smaller in width and thickness than the handy copy machine main body 1, and a stepped portion is formed between the head portion HA and the handy copy machine main body 1. The tip end surface of the head portion HA is
It is formed obliquely from the center toward both sides, and a reading section 2 and a printing section 3 are provided on the sloped sections 1a and 1b, respectively. Further, the handy copy machine body 1 is provided with a power/read/print switch 4 at the lower side of the minus side as shown in the figure, and operation keys 5a and 5b are provided oppositely on both the front and back sides. It will be done. The operation keys 5a and 5b are formed into a flat plate shape, and the handy copy machine main body 1 can be moved back and forth by holding the upper surface portions between the keys by hand. Above ff1Ii! - The reading/printing switch 4 is used to specify the power on/off, reading, and printing operation modes, and the power is turned on when each reading and printing mode is specified. Further, the handy copy machine main body 1 is provided with a clear key 6 and a density adjustment volume 7 for adjusting print density at an end opposite to the side where the reading section 2 and printing section 3 are provided.

The clear key 6 is used to erase the image memory when reading an image, and is used to locate the beginning of image data when printing. In addition, the handy copy machine main body 1 is provided with a power LED 8 in the vicinity of the reading section 3, and a memory LED 9 and a speed warning LED 8 are provided on the upper end side of the front part in the figure.
is placed.

When reading a document using the above-mentioned handy copy machine, the power/read/print selector switch 4 is set to the "read" position.When the power/read/print selector switch 4 is set to the "reader" position, Power on II
IILED8 lights up. In this state, the reading section 2 is brought into contact with the document surface and moved while pressing the operation keys 5a and 5b. If the moving speed of the handy copy machine main body 1 is too fast, a speed warning LEDIO will warn you.

If you want to print out the scanned image data, switch the power/read/print switch 4 to the "Print" position, then bring the print section 3 into contact with the printing paper A (plain paper) and press This is done by moving the handy copy machine main body 1 in the direction of arrow X while pressing keys 5a and 5b.

Next, details of the reading section 2 and printing section 3 provided in the handy copy machine main body 1 will be explained with reference to FIGS. 2 and 3. As shown in FIGS. 2(a) and 2(b), the reading unit 2 is located inside the handy copy machine main body 1 on a sloped portion 1a.
A light [11] consisting of an LED array is arranged in the vicinity of the
This light! ! 111 illuminates the original document B to be read through the reading window 12 provided on the slope portion 1a. Furthermore, a light guide 13 is provided in the handy copy machine main body 1 and extends upward from the vicinity of the slope portion 1a, and a lens 14 and a -dimensional image sensor 15 are sequentially arranged at a predetermined interval on the upper end side of the light guide 13. maintained and placed.

The above-mentioned -dimensional image sensor 15 is, for example, a 1024-bit one-dimensional COD, of which 320 bits (8do
t/mi and 4Qmm width) is used. The lens 14 and the -dimensional image sensor 15 are mounted on a support 16
is held in place by the

This support body 16 is fixed to an inner frame 17 provided inside the handy copy machine main body 1 at a predetermined interval. An electronic component mounting section 18 and a battery storage section 19 are provided adjacent to the support body 16, and the electronic component mounting section 1
The above-mentioned -dimensional image sensor 15 is connected to a circuit board 20 mounted on the circuit board 8 . Further, the circuit board 20 is connected to the clear key 6, the 11 degree adjustment volume 7, and the like.

A thermal head 21, an ink ribbon roll 22, a continuous feed roller 23, and an ink ribbon take-up roll 24 are provided within the inner frame 17, and rubber rollers 25a and 25b are provided between the inner frame 17 and the handy copy machine main body 1.

Gear wheels 26.27.28.29.30 are provided. The rubber rollers 25a, 25b are rotatably connected to the inner frame 17 via a shaft 31, and their outer peripheral surfaces are attached to the slope portions 1a, 1.
It projects slightly to the outside from notches 32 provided on both sides of b. Then, the one rubber roller 25
The gear 26 is fixed coaxially to the side of a. This gear 26 is formed to have a smaller diameter than the rubber roller 25a, and is coupled to a gear 28 with an intermediate gear 27 interposed therebetween. This gear 28 is connected to the shaft of the constant feed roller 23 via a one-way clutch 33.

This one-way clutch 33 is configured to transmit the rotation of the primary side to the secondary side only during printing operation, that is, the rotation of the gear 28 to the constant feed roller 23 side.

Further, an encoder disk 34 is attached to the primary side of the one-way clutch 33, and the gear 28 and the encoder disk 34 are connected to each other regardless of the clutch operation of the one-way clutch 33.
4 are designed to rotate together.

As shown in FIG. 3, the encoder disk 34 is provided with a plurality of slits 35 radially spaced at regular intervals. Then, the LED 36 and the photo sensor 3 are arranged so as to face each other with the encoder disk 34 interposed therebetween.
7 is placed. In this case, the LED 36 is shown in FIG. 2(a).
As shown in FIG. 2, the photo sensor 37 is installed inside the handy copy machine main body 1, and the photosensor 37 is installed inside the inner frame 17. A through hole 38 is provided in a portion of the inner frame 17 located 8@ above the photosensor 37 so that the projected light from the LED 3B passes through the slit 35 of the encoder disk 34 and the through hole 38 and enters the photosensor 37. It has become. That is, the encoder 39 is configured by the encoder disk 34, the LED 36, the photosensor 37, and the like.

Further, on the slope portion 1b of the print section 3, a third
As shown in the figure, a print window 41 and an ink ribbon guide window 42 are provided in parallel. In this case, print window 4
1, the ink ribbon guide window 42 is located inside. The heat generating portion 21a of the thermal head 21 is inserted into the print window 41, and positioned so that its tip surface slightly protrudes from the slope portion 1b. As shown in FIG. 2(b), a slit 43 is provided in the stepped portion of the HandyCobby main body 1 on the side where the operation key 5a is provided, and the ink ribbon roll 22
The thermal transfer ink ribbon 22a pulled out from the slit 43 is led out of the handy copy machine main body 1,
Thereafter, the ink ribbon passes through the heat generating section 218 of the thermal head 21 and is introduced into the interior of the handy copier main body 1 through the ink ribbon guide window 42. The ink ribbon 22a introduced into the main body 1 of the handy copying machine is guided by a shaft 31, an ink ribbon guide 44, and a continuous feeding roller 23, and is wound onto an ink ribbon take-up roll 24. Furthermore, as shown in No. 219(b), the handheld copier main body 1 is formed so that the surface on which the operation key 5b is provided can be opened and closed by a hinge 45, so that the ink ribbon 22a can be replaced and the interior can be inspected. etc. can now be done.

Next, the configuration of the electronic circuit formed on the circuit board 20 will be explained with reference to FIG. 4. The encoder 39 includes the encoder disk 34 and the LED 36 as described above.
, a photosensor 37, etc., and outputs a pulse signal, that is, a movement amount detection signal, depending on the person moving the handy copy machine main body 1.

The movement amount detection signal output from this encoder 39 is
Control section 51, timing signal generation section 52, speed detection section 5
Sent to 3. The control unit 51 includes the power supply/read/
Print changeover switch 4, operation key 5a.

Operation signals are given from a group of keys and switches 54 such as the 5b1 clear key 6 and the density adjustment volume 7, and a temperature detection signal is given from a temperature sensor 55 that detects the temperature of the thermal head 21 and the temperature of the printing paper. and,
The control unit 51 controls the LED unit 50 to turn on and off in response to operation signals from the key and switch group 54 . In addition to controlling the lighting of the LED 8 and memory LED 9 and controlling other parts, the power/read/print selector switch 4
Operation commands Sl and S2 are given to the timing signal generator 52 according to the reading mode or print mode specified by. In this case, the control unit 51 provides the timing signal generating unit 52 with an operation command S1 in the reading mode and an operation command S2 in the print mode.

When the timing signal generating section 52 receives the operation command S1 from the control section 51, it generates a COD exposure timing signal of a constant period, and also reads a predetermined number of times in synchronization with the movement amount detection signal from the encoder 39. Timing signal a1 Serial/parallel conversion signal b1 Clock pulse C
Generates various timing signals such as Further, the timing signal generation section 52 generates a print timing signal when the operation command S2 is given from the control section 51. Then, the C output from the timing signal generating section 52 is
The OD exposure timing signal is sent to the one-dimensional image sensor 15, the reading timing signal a is sent to the binarization circuit 57, and the serial/parallel conversion signal is sent to the serial/parallel conversion section 58.
Then, the clock pulse C is sent to the address counter 61, respectively. The -dimensional image sensor 15 reads the reflected light from the original B in synchronization with the COD exposure timing signal and outputs it to the binarization circuit 57 . This binarization circuit 57
converts the input signal into a black and white binary signal and outputs it to the serial/parallel converter 58.

The serial/parallel converter 58 converts the input signal into a parallel signal every 8 bits using a serial/parallel conversion signal, and outputs the converted signal to the image data memory 60 via the data selector 59. Also, data selector 5
Reference numeral 9 has a data line connected to the control section 51, and either the serial/parallel conversion section 58 or the control section 51 is selected by a select signal d from the control section 51.

The write address (row and column address) of the image data memory 60 is indicated by an address counter 61 and designated via an address selector 62. Further, the read address of the image data memory 60 is given by the control section 51 via the address selector 62. This address selector 62 selects the address counter 61 side in the read mode in response to a select signal e from the control unit 51,
In the print mode, the controller 51 is selected and the address of the image data memory 60 is designated.

When the reading of the document is completed and the mode is switched to the print mode, the control section 51 outputs the operation command S2 to the timing signal generation section 52 as described above, and also outputs the movement state detection signal from the encoder 39. The data selector 5 selects the data stored in the image data memory 60 according to the
9 sequentially. When the control unit 51 reads image data from the image data memory 60, it outputs the image data to the thermal head drive circuit 64, and also outputs the number of black characters in the print data, the temperature detection signal from the temperature sensor 55, and the density adjustment volume. Set the energization time based on the value of 7.

When the thermal head drive circuit 64 receives print data from the print control section 51, the thermal head drive circuit 64 drives the thermal head 2 in synchronization with the timing signal from the timing signal generation section 52.
Drive 1.

Next, the circuit configuration of the binarization circuit 57 will be explained with reference to FIG.

The output of the one-dimensional image sensor 15 is filtered through a low-pass filter (
Noise is cut through L P F ) 65 and provided to an amplifier circuit 86 . The amplifier circuit 66 amplifies the input signal to a level required for binarization. The output of this amplifier circuit 66 is given to the positive terminal of a comparator 67. This comparator 67 is supplied with the output of a VREF2 generating circuit 68 which outputs a constant threshold voltage to its negative terminal. The comparison result of the comparator 67 is then sent to the select circuit 69. The select circuit 69 is an AND gate 69
1.692, an OR gate 693, and an inverter 694, and the output of the comparator 67 is given to one terminal of an AND gate 691.

Further, the output of the amplifier circuit 66 is given to the negative terminal of the comparator 70, and is also applied to a low pass filter (LPF).
71 is applied to a voltage follower circuit 72, where a 70-ting value, which is an integral value of the COD output, is obtained and applied to the positive terminal of the comparator 70. The comparison result of the comparator 70 is applied to one terminal of the AND gate 692 of the select circuit 69 as a 70-biting binary signal.

The read timing signal a of the timing signal generator 52 is applied to a first sampling clock generation circuit 73 and a second sampling clock generation circuit 74, and the output of the first sampling clock generation circuit γ3 is applied to a first sample hold circuit 75 and a second sampling clock generation circuit 74. Sampling clock generation circuit 7
The output of 4 is sent to a second sample and hold circuit 76.

The first sample and hold circuit 75 samples the output of the amplifier circuit 66 at the rHJ level of the sampling clock of the first sampling clock generation circuit 73 shown in FIG. 6(f), and holds it at the rLJ level. Further, the second sample and hold circuit 76 receives the output of the amplifier circuit 66 as shown in FIG.
Sampling is performed at the rHJ level of the sampling clock of the second sampling clock generation circuit 74 shown in Q),
Hold at rLJ level. These held contents are given to the comparator 17.

Therefore, by repeating this operation, the first sample and hold circuit 75 comes to hold the previous COD output of the second sample and hold circuit 16, and the comparator 77 obtains a comparison result between them. The comparison output of this comparator 77 is given to the positive terminal of a comparator 78. This comparator 78 is supplied with the output of a VREFI generating circuit 79 which outputs a constant threshold voltage to its negative terminal. The comparison result of the comparator 79 is then sent to the latch circuit 80.

The latch circuit 80 is supplied with a clock signal from the latch clock generation circuit 81 shown in FIG. 6(h), and the comparator 7
The AND gate 692 of the select circuit 69 selects the comparison result of 9.
and the other terminal of AND gate 691 via inverter 694. The outputs of AND gates 691 and 692 are outputted via OR gate 693.

Next, the operation of the above embodiment will be explained.

When reading information such as characters and images recorded on a document, first turn on the power/read/print switch 4.
Switch from the N source OFF '° position to the 'Read, °' position. When the power/read/print selector switch 4 is switched to the "read" position, the power is turned on and each circuit section becomes operational. At this time, the control unit 51 lights up the power LED 8 in the LED unit 50 to display that the power is turned on, and also sends the operation command S1 to the timing signal generation unit 52.
give to

In this state, as shown in FIG. 2(b), the user moves the reading section 2 formed in the head section HA to the document B.
Touch the desired reading surface of the operation keys 5a, 5b.
While pressing , move the handy copy machine main body 1 toward the front on the operation key 5a side.

At this time, the projection light from the light source 11 is irradiated onto the original IB surface through the reading window 12 provided on the slope portion 1a, and the reflected light is incident on the one-dimensional image sensor 15 via the light guide 13 and lens 14.

Further, as the handy copy machine main body 1 moves, the rubber rollers 25a and 25b rotate in contact with the surface of the document 8, and the rotation is transmitted to the gear 28 via the gears 26 and 21. And these teeth! Encoder disk 3 with rotation of 28
4 rotates at a speed proportional to the moving speed of the handy copy machine main body 1. This rotation of the encoder disk 34 causes the photo sensor 3 to pass from the LED 3B through the slit 35.
The light sent to the photo sensor 7 is controlled intermittently, and the photo sensor 37 outputs a pulse signal.

The pulse signal output from the photo sensor 37 becomes the output of the encoder 39 in FIG. It will be done.

On the other hand, when the timing signal generation section 52 receives the operation command S1 from the control section 51, it generates a CCD exposure timing signal of a constant period and supplies it to the -dimensional image sensor 15, and also applies it to the movement amount detection signal from the encoder 39. Accordingly, a read timing signal a and a serial/parallel conversion signal S are generated and outputted to the binarization circuit 57 and the serial/parallel conversion section 58, respectively. Furthermore, the timing signal generator 52 generates a clock pulse C in synchronization with the serial/parallel conversion signal S, and outputs a clock pulse C to the address counter 6.
Output to 1.

Thus, the above-mentioned -dimensional image sensor 15 outputs a signal corresponding to the light reflected from the surface of the document B, that is, an image signal, in synchronization with the above-mentioned CCD exposure timing signal from the timing signal generating section 52. In this case, in the -dimensional image sensor 15, the shift gate pulse SH in FIG. 6(a), the signals @ charges φ1, φ2 in FIG.
) An output O8 shown in FIG. 3(e) is obtained by the glue set gate pulse R8. The output signal of this -dimensional image sensor 15 is then sent to a binarization circuit 57.

The binarization circuit 57 converts the m-image signal sent from the -dimensional image sensor 15 into a binarization signal in synchronization with the read timing signal a from the timing signal generation section 52, and converts the m-image signal sent from the -dimensional image sensor 15 into a binarization signal, and converts it into a binary signal. Output to 58. In other words, in the binarization circuit 57, the -dimensional image sensor 1
The output from 5, that is, the COD output, is sent to the low-pass filter 6.
5, the reset noise is cut, and the signal is applied to the amplifier circuit 66. The amplification circuit 66 amplifies it to the level required for binarization, and the comparator 67.7
Sent to 0. The comparator 67 compares it with a constant threshold voltage of the VREF2 generating circuit 67, and the comparison result is applied to the AND gate 691 of the select circuit 69. Further, the comparator 70 compares the floating value obtained through the low-pass filter 71 and the voltage follower circuit 72, and provides the result of this comparison to the AND gate 692 of the select circuit 69.

On the other hand, the output of the amplifier circuit 66 is sent to the first sample and hold circuit 75 and the second sample and hold circuit 16. In this state, the read timing signal a from the timing signal generator 52 is transmitted to the first sampling clock generator 73,
When applied to the second sampling clock generation circuit 74, the first sampling clock generation circuit 73 generates the sixth clock (
The sampling clock shown in f) is output, and the contents of the first sample and hold circuit 75 are sampled at the rHJ level and held at the rLJ level. Similarly, from the second sampling clock generation circuit 74,
A sampling clock shown in is output, and the contents of the second sample and hold circuit 76 are sampled at the rHJ level and held at the rLJ level.

The contents held in the first sample and hold circuit 75 and the second sample and hold circuit 76 are provided to the comparator 77. In this case, the COD output of the first sample-and-hold circuit 75 given to the comparator 77 is the one before the COD output of the second sample-and-hold circuit 76, and the results of these comparisons are given to the comparator 77.
It is output from Here, the comparator 77 is COD
When the output changes in an alternating current manner, a large output is obtained, and conversely, when the COD output changes in a direct current manner, a small output is obtained. And this comparator 77
The output of VREFI generating circuit 79 is applied to comparator 78 and compared with a constant threshold voltage of VREFI generating circuit 79.

In this case, the comparator 78 outputs "1" when the output from the comparator 77 is sufficiently large and exceeds a certain threshold voltage of the VREFI generation circuit 79, and outputs "1" when the output from the comparator 77 is small and exceeds the certain threshold voltage of the VREFI generation circuit 79. rOJ when it is below a certain threshold voltage of
Generate output. This output is latched by the latch circuit 80 by the latch clock shown in FIG. 6(h) of the latch clock generation circuit 81, and then
sent to.

Therefore, if the COD output changes significantly in an AC manner and the output from the comparator 77 exceeds a certain threshold voltage of the VREF1 generation circuit 79, the value is "1".
Since the output is given to the AND gate 692 of the select circuit 69 via the latch circuit 80, the output of the comparator 70 is sent out as a 70-ting binary signal. In this case, the AND gate 691 is
0'' output, the output of the comparator 67 is never selected. On the other hand, the COD output changes DC, and the output from comparator γ1 is VRE.
When the threshold voltage of the FI generating circuit 79 is below a certain threshold, a "0" output is given from the latch circuit 80 to the inverter 694 of the select circuit 69. Then, inverter 6
94, a "1" output is given to the AND gate 691, and the comparator 67 then outputs a binarized signal.

In this case, since the rOJ output is given to the AND gate 692, the output of the comparator 70 is not selected.

In this way, the binarized signal obtained from the binarization circuit 57 is sent to the serial/parallel converter 58. This serial/parallel converter 58 converts the input signal into parallel image data, for example, every 8 bits in synchronization with the serial/parallel conversion signal sent from the timing signal generator 52, and outputs it to the data selector 59. do. This data selector 59 is switched to the serial/parallel converter 58 side by select d from the controller 51 when the reading mode is designated. Therefore, the image data output from the serial/parallel converter 58 is transferred to the image data memory 6 via the data selector 59.
Sent to 0.

The address of the image data memory 60 is designated via the address selector 62, but at this time the address selector 62 is switched to the address counter 61 side by the select signal e from the control section 51.

Therefore, the address of the image data memory 60 is specified by the count output of the address counter 61. The address counter 61 sequentially changes the digit address to "+1" by the clock pulse C from the timing signal generator 52.
and specifies the address of the image data memory 60. Then, when one line of image data is written into the image data memory 60, the timing signal generating section 52 stops generating the timing signal, and starts the next transition vJ! from the three encoders.
It will be in a standby state until a detection signal is sent. Thereafter, similar operations are repeated, and image data read from document B is sequentially written into image data memory 60.

Next, the operation when printing out the image data read from document B as described above will be explained. When printing out image data, use the N source/read/
Switch the print changeover switch 4 to the print position. By switching the power/read/print selector switch 4, the print mode is entered, and the control unit 51 outputs the select signal d,
e, the data selector 59 and address selector 62
is switched to the control section 51 side. In this state, the user
As shown in the figure, the print section 3 of the head section HA is brought into contact with the printing paper A, and the handy copy machine main body 1 is moved in the direction of the arrow X shown while pressing the operation keys 5a and 5b.

As the handy copy machine body 1 moves, the rubber roller 2
5a125b rotates, and the rotation is transmitted to gear 28 via gears 26 and 27.

As the gear 28 rotates, the encoder disk 34 rotates, and a movement amount detection signal is extracted from the photosensor 31 in accordance with the movement speed of the handy copy machine main body 1, as in the above reading.

Further, the rotation of the gear 28 is transmitted to the constant speed feed roller 23 via the one-way clutch 33, and further the rotation of the gear 29.
0 to the take-up roll 24. As a result, the constant speed feed roller 23 and the take-up roll 24 rotate, and the ink ribbon roll 22 passes through the stepped slit 43, the heat generating part 21a1 of the thermal head 21, the ink ribbon guide window 42, the shaft 31, and the ink ribbon guide 44. , the ink ribbon 22a guided by the constant speed feed roller 23
Wind up. In this case, the continuous feed roller 23 is adjusted to the amount of movement of the handy copier main body 1 so as not to generate a relative speed between the printing paper A and the ink ribbon 22a as the handy copier main body 1 moves. and rotate.

On the other hand, the movement amount detection signal output from the photosensor 37 is sent to the control section 51, the timing signal generation section 52, and the speed detection section 53 as an output signal of the encoder 39, as described above. The timing signal generating section 52 includes:
In response to the movement m detection signal sent from the encoder 39, a one-line print command is output to the control section 51, and a print timing signal is output to the thermal head drive circuit 64. Further, the control unit 51 sequentially specifies the row and digit addresses of the image data memory 60 according to the movement m detection signal from the encoder 39, and selects the image data stored in the image data memory 60 via the data selector 59. The data is read out and output to the thermal head drive circuit 64 one row at a time.

The thermal head drive circuit 64 outputs a drive signal to the thermal head 21 according to data from the control section 51. Further, when the control unit 51 receives a one-line print command from the timing signal generation unit 52, the control unit 51 outputs the number of black characters in the print data, the head temperature from the temperature sensor 55, and the density adjustment volume 7.
The energization time for the thermal head 21 is set based on the adjustment value and the like.

The image data stored in the image data memory 60 in this manner is output line by line to the thermal head 21 and printed.

Therefore, in this way, CO that is given intermittently
The difference between adjacent COD outputs of the D output is detected, and if this output difference exceeds a predetermined value, a floating system binary signal is selected, while if the output difference is less than a predetermined value, a single Schresh voltage is selected. Since the binary signal is selected based on , an accurate binary signal can be output regardless of whether the reading output on the document surface changes in an alternating current or direct current manner. Can be done.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be implemented with appropriate modifications without changing the gist.

[Effects of the Invention] According to the present invention, it is possible to select a 211 signal using a floating method or a 21iii signal using a single threshold voltage, depending on the output difference between adjacent COD outputs that are intermittently applied. As a result, an accurate binary signal can be obtained regardless of whether the output read from the document surface changes in an alternating current manner or in a direct current manner.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the external configuration of an embodiment of the present invention;
Fig. 2(a) is a sectional view showing the internal structure of Fig. 1, Fig. 2(b) is a sectional view taken along the line I-I in Fig. 1(a), and Fig. 3 shows the main internal components. FIG. 4 is a block diagram showing the overall configuration of the electronic circuit, FIG. 5 is a block diagram showing the circuit configuration of the binarization circuit used in the same example, and FIG. 6 is the same binary circuit. FIG. 7 is a waveform diagram for explaining a conventional COD output binarization circuit. 1... Handy copy machine body, 2... Reading section, 3...
...Print section, 4...Power/read/print switch, 5a, 5b...Operation key, 6...Clear key, 7...Density adjustment volume, 8...Power LED
19...Memory LED110...Speed warning ED,
11...Light source, 11a...Light source body, 11b...
Mirror, 12...Reading window, 13...Light guide, 14...
・Lens, 15...-dimensional image sensor, 16...
- Support body, 17... Inner frame, 18... Electronic component mounting section, 19... Battery storage section, 20... Circuit board, 2
DESCRIPTION OF SYMBOLS 1... Thermal head, 22... Ink ribbon roll, 23... Continuous feed roller, 24... Ink ribbon winding roll, 25a, 25b... Rubber roller, 2
6-30...Gear, 32...Notch, 33...1
Directional clutch, 34... Encoder disk, 35...
...Slit, 36...LED, 37...Photo sensor, 38...Through hole, 39...Encoder, 41...
...Print window, 42...Ink ribbon guide window, 4
3...Slit, 44...Ink ribbon guide, 4
5... Hinge, 51... Control unit, 52... Timing signal generation unit, 53... Speed detection unit, 54... Switch group, 55... Temperature sensor, 56... Amplifier,
51... A/D2 converter, 58... Serial/parallel converter, 59... Data selector, 60... Image data memory, 61... Address counter, 62...
・Address selector, 64... Thermal head drive circuit, 67, 70.77.78... Comparator, 68
...VREF2 generation circuit, 69...select circuit,
72... Voltage follower, 13... First sample clock generation circuit, 74... Second sample clock generation circuit, 75... First sample hold circuit, 76
...Second sample hold circuit, 79...VREF
I generation circuit, 80... latch circuit.

Claims (1)

[Claims] an output means for intermittently outputting a screen signal from an image sensor that reads data on a document surface; and a first binary value that binarizes the image signal output from the output means based on an integral value of the image signal. a second binarizing means for binarizing the image signal output from the output generating means based on a single threshold voltage; output difference detection means for detecting a difference between image signals; and when the output difference detected by the output difference detection means is greater than or equal to a predetermined value, the binarized signal of the first binarization means is selected; is below a predetermined value, the second
1. A binarization circuit for image sensor output, comprising: selection means for selecting a binarized signal of the binarization means.