JP2540818B2 - Image sensor output binarization circuit - Google Patents

Description

Description: 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, in an ultra-small handy copy machine or the like, the light of a light source is applied to the original surface, and the reflected light from the original surface is received by an image sensor, for example, a CCD to read image data. Various image data reading means are used.

By the way, it is known that the CCD used as such an image sensor has an output voltage that changes according to the rate of change of the contrast of white and black on the original surface. Therefore, for example, as shown in FIG. 7 (a), when the image data of the original surface having a white: black relationship of 1: 1 is read, and as shown in the same figure (b), the white: black relationship is The case where the image data of the document surface of 5: 1 is read, the latter raises the overall voltage level.

For this reason, conventionally, as a means for binarizing the output of the CCD, a so-called floating system has been adopted in which the output of the CCD is compared with a floating value obtained by integrating the output of the CCD to obtain a binarized output. There is.

However, when such a floating system is adopted, there is no problem in the case where a white portion and a black portion appear alternately on the document surface as described above, and the reading output thereof has an AC change, so-called solid white or If the read output has a direct current change, such as solid black,
Since the CCD output at this time and the output obtained by integrating the CCD output are always equal to each other, the binarized output is fixed to either "H" or "L", and accurate binarization is performed. There was a drawback that no signal was obtained.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an accurate binarization signal can be obtained regardless of whether the reading output of the document surface changes AC or DC. It is an object of the present invention to provide a binarization circuit for the obtained image sensor output.

SUMMARY OF THE INVENTION An image sensor output binarization circuit according to the present invention includes an output means for outputting an intermittent image signal from an image sensor for reading data on a document surface, and an image signal output by the output means. First binarizing means for binarizing based on the integral value of the image signal, second binarizing means for binarizing the image signal output by the output means based on a single shresh voltage, There is provided output difference detection means for detecting a difference between the image signals output from the output means and adjacent to each other. When the output difference detected by the detection means exceeds a predetermined value, the first 2 The binarized signal of the binarizing means is selected, and the binarized signal of the second binarizing means is selected when the output difference is equal to or less than a predetermined value.

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

In this embodiment, an example in which the present invention is applied to a handy copy machine is shown. FIG. 1 shows an external configuration of a handy copy machine embodying the present invention. In the figure, reference numeral 1 is a main body of a handy copying machine, for example, having a width of 70 mm, a thickness of 30 mm and a height of about 160 mm, an effective read width, an effective print width of 40 mm, a read memory length of 200 mm and a read dot density of 8 dots mm, print dot density is assumed to be 8dot / mm. Then, the handy copy machine body 1 is provided with a head portion HA for reading and printing at the tip portion, that is, the lower end portion in the figure. The head HA has a width and thickness smaller than that of the main body 1 of the handy copy machine, and a step D is formed between the main body HA and the main body 1 of the handy copy machine. The tip surface of the head portion HA is formed obliquely from the center toward both side portions, and the reading portion 2 and the printing portion 3 are provided on the inclined surface portions 1a and 1b, respectively. In addition, the main body 1 of the handy copying machine is provided with a power / reading / printing changeover switch 4 at a lower part of one side in the drawing, and operation keys 5a and 5b are provided so as to face both front and back surfaces. To be The operation keys 5a and 5b are formed in a flat plate shape, and the handy copy machine main body 1 can be moved back and forth by sandwiching the upper surface portions by hand. The power supply / reading / printing changeover switch 4 is for designating each operation mode of powering on / off, reading, and printing, and the power is turned on when each reading, printing mode is designated.
Further, the handy copy machine main body 1 is provided with a clear key 6 and a density adjusting volume 7 for adjusting print density at the end opposite to the side where the reading section 2 and the printing section 3 are provided. The clear key 6 is used for erasing the image memory at the time of reading an image, and for finding the beginning of image data at the time of printing. In addition, the handy copy machine main body 1 is provided with a power supply LED 8 in the vicinity of the reading unit 3, and a memory LED 9 and a speed warning are provided on the upper end side of the front face in the figure.
The LED 10 is arranged.

Then, when the manuscript is read by the handy copying machine, the power / read / print changeover switch 4 is set to the "read" position. When the power / read / print selector switch 4 is set to the “read” position, the power turns on and the power turns on.
LED8 lights up. In this state, the reading unit 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 body 1 is too fast, a speed warning is issued.
Warning with LED10.

When the read image data is to be printed out, the power source / read / print changeover switch 4 is switched to the "print" position, and then the print section 3 is printed.
This is performed by bringing the handy copy machine main body 1 into contact with (plain paper) and moving the operation keys 5a and 5b in the direction of the arrow X.

Next, details of the reading unit 2 and the printing unit 3 provided in the handy copy machine body 1 will be described with reference to FIGS. 2 and 3. As shown in FIGS. 2 (a) and 2 (b), the reading unit 2 has a slanted portion 1a in the handy copy machine main body 1.
A light source 11 composed of an LED array is disposed in close proximity to, and the read original B is illuminated by the light source 11 through a reading window 12 provided in the slope 1a. Further, in the main body 1 of the handy copying machine, a light guide 13 which is directed upward from the vicinity of the inclined surface portion 1a is provided. It is kept and arranged. The one-dimensional image sensor 15
Is, for example, a 1024-bit one-dimensional CCD, of which 320 bits (in the case of 8dot / mm and 40mm width) are used. The lens 14 and the one-dimensional image sensor 15 are held at predetermined positions by the support 16. The support 16 is fixed to an inner frame 17 provided inside the main body 1 of the handy copy machine with a predetermined space. Then, an electronic component mounting portion 18 and a battery storage portion 19 are provided in the vicinity of the support body 16,
The one-dimensional image sensor 15 is connected to the circuit board 20 mounted on the electronic component mounting portion 18. Further, the clear key 6, the density adjusting volume 7 and the like are connected to the circuit board 20.

A thermal head 21, an ink ribbon roll 22, a constant velocity feed roller 23, and an ink ribbon take-up roll 24 are provided inside 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. Gears 26, 27, 28, 29, 30 are provided. The rubber rollers 25a and 25b are mounted on the inner frame 17 by a shaft 31.
Is rotatably mounted through the outer peripheral surface of the slope 1a,
The cutouts 32 provided on both sides of the 1b project slightly outward. The gear 26 is coaxially fixed to the side portion of the one rubber roller 25a. The gear 26 has a diameter smaller than that of the rubber roller 25a and is coupled to the gear 28 with an intermediate gear 27 interposed. This gear 28 is 1
It is connected to the shaft of the constant velocity feed roller 23 via a directional clutch 33. The one-way clutch 33 is configured to transmit the rotation of the primary side to the secondary side only during the printing operation, that is, the rotation of the gear 28 to the constant velocity feed roller 23 side. An encoder disc 34 is provided on the primary side of the one-way clutch 33.
The gear 28 and the encoder disk 34 rotate together regardless of the clutch operation of the one-way clutch 33. As shown in FIG. 3, the encoder disk 34 has a plurality of slits 35 radially provided at regular intervals. Then, the LED 36 and the photo sensor 37 are arranged so as to face each other with the encoder disk 34 in between. In this case, the LED 36 is mounted inside the handy copy machine main body 1 and the photo sensor 37 is mounted inside the inner frame 17, as shown in FIG.
A through hole 38 is provided in the portion of the inner frame 17 where the photo sensor 37 is mounted, so that the projection light from the LED 36 enters the photo sensor 37 through the slit 35 of the encoder disk 34 and the through hole 38. Has become. That is, the encoder 39 is configured by the encoder disk 34, the LED 36, the photo sensor 37, and the like.

In addition, the slope portion 1b of the printing unit 3 has a third
As shown in the figure, the print window 41 and the ink ribbon guide window
42 are provided in parallel. In this case, the ink ribbon guide window 42 is provided inside the print window 41. In the print window 41, the thermal head 21
The heat generating portion 21a is inserted and positioned so that its tip end surface slightly protrudes from the sloped portion 1b. The step D on the side of the handy copy machine body 1 on which the operation keys 5a are provided is provided with a slit 43 as shown in FIG. 2B, and the thermal transfer ink drawn from the ink ribbon roll 22 is transferred. The ribbon 22a is led out from the slit 43 to the outside of the main body 1 of the handy copy machine, and then passes through the heating portion 21a of the thermal head 21 and is introduced from the ink ribbon guide window 42 into the main body 1 of the handy copy machine. Ink ribbon 22a introduced inside the handy copy machine body 1
Is the shaft 31, the ink ribbon guide 44, and the constant velocity feed roller 23.
And is wound around the ink ribbon take-up roll 24. Further, as shown in FIG. 2B, the surface of the handy copy machine main body 1 on which the operation keys 5b are provided is formed so as to be openable and closable by a hinge 45. It can be inspected.

Next, the structure of the electronic circuit formed on the circuit board 20 will be described with reference to FIG. The encoder 39 includes the encoder disk 34, the LED 36, and the photo sensor 3 as described above.
It is composed of 7 etc., and outputs a pulse signal corresponding to the movement amount of the handy copy machine body 1, that is, a movement amount detection signal. The movement amount detection signal output from the encoder 39 is sent to the control unit 51, the timing signal generation unit 52, and the speed detection unit 53. The control unit 51 includes keys such as the power / read / print changeover switch 4, operation keys 5a and 5b, a clear key 6, a density adjusting volume 7 and a switch group 54.
An operation signal is given from the temperature sensor 55 and a temperature sensor 55 that detects the temperature of the thermal head 21 and the temperature of the printing paper gives a temperature detection signal. Then, the control unit 51 controls the lighting of the power LED 8 and the memory LED 9 in the LED unit 50 and the control operation of each other unit according to the operation signal from the keys and the switch group 54, and at the same time, the power / read / print changeover switch 4 The operation command S ₁ to the timing signal generator 52 according to the reading mode or the print mode specified by
Give S ₂ . In this case, the control unit 51 controls the operation command S ₁ in the read mode and the operation command S ₁ in the print mode.
S ₂ is supplied to the timing signal generator 52.

When the operation signal S ₁ is given from the control unit 51, the timing signal generation unit 52 generates a CCD exposure timing signal of a constant cycle, and a predetermined number in synchronization with the movement amount detection signal from the encoder 39. Various timing signals such as a read timing signal a, a serial / parallel conversion signal b, and a clock pulse c are generated. Further, the timing signal generator 52, when the operation command S ₂ is given from the controller 51,
Generates a print timing signal. The CCD exposure timing signal output from the timing signal generator 52 is sent to the one-dimensional image sensor 15, the read timing signal a is sent to the binarization circuit 57, and the serial / parallel conversion signal b is sent to the serial / parallel converter 58. , The clock pulse c is sent to the address counter 61, respectively. The one-dimensional image sensor 15 reads the reflected light from the document B in synchronization with the CCD exposure timing signal and outputs it to the binarization circuit 57.
The binarization circuit 57 converts the input signal into a monochrome binary signal and outputs it to the serial / parallel converter 58.

The serial / parallel converter 58 converts the input signal into a parallel signal in units of, for example, 8 bits by the serial / parallel conversion signal b, and outputs the parallel signal to the image data memory 60 via the data selector 59. In addition, the data selector 59
The data line is connected to the control unit 51, and the serial / parallel conversion unit 58 is operated by the select signal d from the control unit 51.
Alternatively, one of the control units 51 is selected. The write address (row and column address) of the image data memory 60 is indicated by the address counter 61 and designated via the address selector 62. Further, the read address of the image data memory 60 is given from the control unit 51 via the address selector 62. The address selector 62 selects the address counter 61 side in the read mode and the controller 51 in the print mode by the select signal e from the control unit 51 to specify the address of the image data memory 60.

Then, when the reading of the document is completed and then the mode is switched to the print mode, the control unit 51 outputs the operation command S ₂ to the timing signal generation unit 52 as described above and also detects the movement amount from the encoder 39. The data stored in the image data memory 60 is sequentially read out via the data selector 59 according to the signal. When the control unit 51 reads out the image data from the image data memory 60, the control unit 51 outputs the image data to the thermal head drive circuit 64, and the number of black characters of the print data,
The energization time is set based on the temperature detection signal from the temperature sensor 55 and the value of the density adjusting volume 7. When the print data is sent from the controller 51, the thermal head drive circuit 64 drives the thermal head 21 in synchronization with the timing signal from the timing signal generator 52.

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

The output of the one-dimensional image sensor 15 has its noise cut through a low pass filter (LPF) 65 and is given to an amplifier circuit 66. The amplifier circuit 66 amplifies the input signal to a level required for binarization. The output of the amplifier circuit 66 is given to the positive terminal of the comparator 67. The output of the V _REF2 generating circuit 68 that outputs a constant shresh voltage is applied to the negative terminal of the comparator 67. Then, the comparison result of the comparator 67 is sent to the select circuit 69. Select circuit 69
Is AND gate 691, 692, OR gate 693, inverter 6
The output of the comparator 67 is given to one terminal of the AND gate 691.

Further, the output of the amplifier circuit 66 is given to the negative terminal of the comparator 70, and a low-pass filter (LPF) 71,
It is given to the voltage follower circuit 72, where the floating value which is the integrated value of the CCD output is obtained and the comparator
Applied to the positive terminal of 70. And this comparator
The comparison result of 70 is given to one terminal of the AND gate 692 of the select circuit 69 as a floating binary signal.

The read timing signal a of the timing signal generator 52 is given to the first sampling clock generating circuit 73 and the second sampling clock generating circuit 74, and the output of the first sampling clock generating circuit 73 is supplied to the first sample hold circuit 75 and the second sampling hold circuit 75. The output of the sampling clock generation circuit 74 is sent to the second sample hold circuit 76. The first sample hold circuit 75 samples the output of the amplifier circuit 66 at the "H" level of the sampling clock of the first sampling clock generating circuit 73 shown in FIG. 6 (f) and holds it at the "L" level. In addition, the second sample hold circuit 76
6 samples the output of the amplifier circuit 66 at the "H" level of the sampling clock of the second sampling clock generating circuit 74 shown in FIG. 6 (g) and holds it at the "L" level. The contents of these holds are given to the comparator 77. Therefore, by repeating this operation, the first sample hold circuit 75 holds the CCD output immediately before the second sample hold circuit 76, and the comparison result is obtained from the comparator 77. The comparison output of the comparator 77 is given to the positive terminal of the comparator 78. The output of a V _REF1 generating circuit 79 which outputs a constant shresh voltage is given to the negative terminal of the comparator 78. Then, the comparison result of the comparator 79 is sent to the latch circuit 80.

The latch circuit 80 is supplied with the clock signal of the latch clock generation circuit 81 shown in FIG. 6 (h), supplies the comparison result of the comparator 79 to the other terminal of the AND gate 692 of the select circuit 69, and also through the inverter 694. It is given to the other terminal of the gate 691. And And Gate 69
The outputs of 1 and 692 are output via the OR gate 693.

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

When reading information such as characters and images recorded on a document, first, the power / read / print switching switch 4 is switched from the "power off" position to the "read" position. When the power / reading / printing changeover switch 4 is switched to the "reading" position, the power is turned on and the respective circuit parts are in the operating state. Further, at this time, the control unit 51 controls the power supply L in the LED unit 50.
The ED8 lights up, indicating that the power is on,
The operation command S ₁ is given to the timing signal generator 52. Then, in this state, the user brings the reading unit 2 formed on the head unit HA into contact with the desired reading surface of the document B while pressing the operation keys 5a and 5b as shown in FIG. 2 (b). The main body 1 of the handy copy machine is moved toward the front on the operation key 5a side. At this time, the projection light from the light source 11 is applied to the surface of the original B through the reading window 12 provided in the inclined surface portion 1a, and the reflected light is passed through the light guide 13 and the lens 14 to the one-dimensional image sensor.
Incident on 15.

Further, as the main body 1 of the handy copying machine moves, the rubber rollers 25a and 25b rotate in contact with the surface of the document B, and the rotation is transmitted to the gear 28 via the gears 26 and 27. Then, with the rotation of the gear 28, the encoder disk 34 rotates at a speed proportional to the moving speed of the main body 1 of the handy copy machine. The rotation of the encoder disk 34 intermittently controls the light sent from the LED 36 to the photo sensor 37 via the slit 35, 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. 4, and is sent to the control unit 51, the timing signal generation unit 52, and the speed detection unit 53 as a movement amount detection signal for the main body 1 of the handy copy machine. To be

On the other hand, the timing signal generator 52, when the operation command S ₁ is given from the controller 51, generates a CCD exposure timing signal of a constant cycle and gives it to the one-dimensional image sensor 15 and a movement amount detection signal from the encoder 39. In response to the read timing signal a and the serial / parallel conversion signal b, and the binarization circuit 57 and the serial / parallel conversion unit 58.
Output to each. Furthermore, the timing signal generator 52 is
A clock pulse c is generated in synchronization with the serial / parallel conversion signal b and output to the address counter 61.

Therefore, the one-dimensional image sensor 15 outputs a signal corresponding to the reflected light from the surface of the original B, that is, an image signal, in synchronization with the CCD exposure timing signal from the timing signal generator 52. In this case, in the one-dimensional image sensor 15, the shift gate pulse SH of FIG. 6 (a), the signal charges φ1, φ2 of FIG. 6 (b), and FIG. 6 (d).
Output shown in (e) of the figure by reset gate pulse RS of
OS is obtained. Then, the output signal of the one-dimensional image sensor 15 is sent to the binarization circuit 57.

The binarization circuit 57 converts the image signal sent from the one-dimensional image sensor 15 into a binarized signal in synchronization with the read timing signal a from the timing signal generator 52,
Output to the serial / parallel conversion unit 58. That is, in the binarization circuit 57, the output from the one-dimensional image sensor 15, that is, the CCD output is given to the low-pass filter 65,
The reset noise is cut and given to the amplifier circuit 66. Then, the amplifier circuit 66 amplifies the signal to a level required for binarization and sends it to the comparators 67 and 70. In the comparator 67, it is compared with a constant threshold voltage of the V _REF2 generating circuit 67, and the comparison result is given to the AND gate 691 of the select circuit 69. The comparator 70 includes a low-pass filter 71 and a voltage follower circuit.
It is compared with the floating value obtained via 72, and the comparison result is given to the AND gate 692 of the select circuit 69.

On the other hand, the output of the amplifier circuit 66 is the first sample hold circuit.
75, sent to the second sample and hold circuit 76. In this state, when the read timing signal a from the timing signal generating section 52 is given to the first sampling clock generating circuit 73 and the second sampling clock generating circuit 74, the first sampling clock generating circuit 73 causes the reading timing signal a shown in FIG. The sampling clock shown in is output, the contents of the first sample hold circuit 75 are sampled at the “H” level,
Hold at "L" level. Similarly, the second sampling clock generation circuit 74 outputs the sampling clock shown in FIG.
The contents of 76 are sampled at the "H" level and held at the "L" level. The contents held in the first sample hold circuit 75 and the second sample hold circuit 76 in this way are given to the comparator 77. In this case, the first sample hold circuit 75 provided to the comparator 77
The CCD output of becomes the one before the CCD output of the second sample hold circuit 76, and the comparison result of these is the comparator output.
It is output from 77. Here, the comparator 77 outputs a large output when the CCD output changes AC-wise.
On the contrary, when the CCD output changes in DC, a small output is obtained. Then, the output of the comparator 77 is given to the comparator 78 and compared with the constant threshold voltage of the V _REF1 generating circuit 79. In this case, the comparator 78 has a sufficiently large output from the comparator 77 that V
Outputs "1" when the constant threshold voltage of _REF1 generating circuit 79 is exceeded, and outputs "0" when the output of comparator 77 is small and is less than the constant threshold voltage of V _REF1 generating circuit 79. To occur. Then, this output is sent to the select circuit 69 after being latched in the latch circuit 80 by the latch clock shown in FIG. 6 (h) of the latch clock generation circuit 81. Therefore, if the CCD output changes greatly in an alternating current, and the output from the comparator 77 exceeds the constant threshold voltage of the V _REF1 generating circuit 79, the "1" output is output via the latch circuit 80 to the select circuit.
Since it is given to the AND gate 692 of 69, the comparator 7
The output of 0 is sent out as a floating binary signal. In this case, since the AND gate 691 is provided with the "0" output from the inverter 694, the output of the comparator 67 is not selected. On the other hand, when the CCD output changes in a direct current, and the output from the comparator 77 is below a certain threshold voltage of the V _REF1 generating circuit 79, a “0” output is output from the latch circuit 80 by the inverter 694 of the select circuit 69.
Given to. Then, the output of "1" from the inverter 694 comes to be given to the AND gate 691, and this time, the binary signal is outputted from the comparator 67.
In this case, since the AND gate 692 is provided with the "0" output, 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. The serial / parallel converter 58 converts the input signal into parallel image data, for example, every 8 bits in synchronization with the serial / parallel converted signal b sent from the timing signal generator 52, and outputs it to the data selector 59. To do. When the reading mode is designated, the data selector 59 selects the serial / parallel converter by selecting d from the controller 51.
It has been switched to the 58 side. Therefore, the image data output from the serial / parallel converter 58 is sent to the image data memory 60 via the data selector 59.

The address of the image data memory 60 is an address selector
The address selector 62 is specified at this time.
Is switched to the address counter 61 side by a select signal e from the control unit 51. Therefore, the address counter
The count output of 61 addresses the image data memory 60. In the address counter 61, the digit address is sequentially incremented by "+1" by the clock pulse c from the timing signal generator 52, and the address of the image data memory 60 is designated. Then, when the image data memory 60 writes one row of image data, the timing signal generator 52 stops generating the timing signal and waits until the encoder 39 sends the next movement amount detection signal. It becomes a state. The same operation is repeated thereafter, and the image data read from the original B is sequentially written in the image data memory 60.

Next, the operation for printing out the image data read from the document B as described above will be described.
When printing out the image data, the power source / read / print switch 4 is switched to the print position.
When the power / read / print changeover switch 4 is switched, the print mode is set, and the control unit 51 selects the select signal d,
The data selector 59 and the address selector 62 are switched to the control unit 51 side by e. In this state, the user brings the print unit 3 of the head unit HA into contact with the printing paper A as shown in FIG. 1, and moves the handy copy machine body 1 in the direction of the arrow X in the figure while pressing the operation keys 5a and 5b. The rubber rollers 25a and 25b rotate with the movement of the main body 1 of the handy copying machine, and the rotation is transmitted to the gear 28 via the gears 26 and 27. Then, the encoder disk 34 rotates in accordance with the rotation of the gear 28, and the movement amount detection signal is taken out from the photo sensor 37 in accordance with the movement speed of the main body 1 of the handy copying machine, as in the above reading.

The rotation of the gear 28 is transmitted to the constant velocity feed roller 23 via the one-way clutch 33, and further to the take-up roll 24 via the gears 29 and 30. As a result, the constant-speed feed roller 23 and the take-up roll 24 rotate, and the shaft 31, ink ribbon guide passes from the ink ribbon roll 22 through the slit 43 of the step D, the heat generating portion 21a of the thermal head 21, the ink ribbon guide window 42. 44. The ink ribbon 22a guided by the constant velocity feed roller 23 is wound up. In this case, the constant velocity feed roller 23 is adjusted to the movement amount of the handy copy machine body 1 so that the relative speed is not generated between the printing paper A and the ink ribbon 22a as the handy copy machine body 1 moves. Rotate.

On the other hand, the movement amount detection signal output from the photo sensor 37 is sent to the control unit 51, the timing signal generation unit 52, and the speed detection unit 53 as the output signal of the encoder 39 as described above. The timing signal generation unit 52 is a control unit according to the movement amount detection signal sent from the encoder 39.
A one-line print command is output to 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 column addresses of the image data memory 60 according to the movement amount detection signal from the encoder 39,
The image data stored in the image data memory 60 is read out via the data selector 59, and the thermal head drive circuit is read.
Output one line to 64. This thermal head drive circuit
64 outputs a drive signal to the thermal head 21 according to the data from the control unit 51. Further, when a one-line print command is given from the timing signal generator 52, the controller 51 controls the thermal head 21 based on the number of black characters in the print data, the head temperature from the temperature sensor 55, the adjustment value of the density adjustment volume 7, and the like. The energizing time will be set.

In this way, the image data stored in the image data memory 60 is output to the thermal head 21 line by line,
Printing is processed.

Therefore, in this way CC will be given intermittently
Detects the difference between adjacent CCD outputs of D output, and when this output difference exceeds a specified value, selects the binary signal by the floating method, while when the output difference is less than the specified value, a single shresh Since the binarized signal based on the voltage is selected, an accurate binarized signal is output regardless of whether the reading output on the original surface changes AC-wise or DC-wise. be able to.

The present invention is not limited to the above-described embodiment, and can be appropriately modified and implemented without changing the gist.

[Effect of the Invention] According to the present invention, a binarized signal by a floating system or a binarized signal at a single shresh voltage is selected according to the output difference between adjacent CCD outputs that are intermittently applied. Since this is possible, an accurate binarized signal can be obtained regardless of whether the output read from the original surface changes AC-wise or DC-wise.

[Brief description of drawings]

FIG. 1 is a perspective view showing an external configuration of an embodiment of the present invention,
2 (a) is a sectional view showing the internal structure of FIG. 1, FIG. 2 (b) is a sectional view taken along the line II-II of FIG. 2 (a), and FIG. FIG. 4 is a perspective view taken out, FIG. 4 is a block diagram showing a configuration of the entire electronic circuit, FIG. 5 is a block diagram showing a circuit configuration of a binarizing circuit used in the embodiment, and FIG. FIG. 7 is a waveform diagram for explaining the digitizing circuit, and FIG. 7 is a diagram for explaining a conventional CCD output binarizing circuit. 1 ... Handy copy machine main body, 2 ... reading unit, 3 ... printing unit, 4 ... power supply / reading / printing switch,
5a, 5b ... Operation key, 6 ... Clear key, 7 ... Density adjustment volume, 8 ... Power LED, 9 ... Memory LED, 10 ...
… Speed warning LED, 11… Light source, 11a… Light source body, 11b…
… Mirror, 12 …… reading window, 13 …… light guide, 14 …… lens,
15 ... One-dimensional image sensor, 16 ... Support, 17 ... Inner frame, 18 ... Electronic component mounting part, 19 ... Battery storage part, 20
...... Circuit board, 21 ...... Thermal head, 22 ...... Ink ribbon roll, 23 …… Constant speed feed roller, 24 …… Ink ribbon winding roll, 25a, 25b …… Rubber roller, 26 to 30 ……
Gears, 32 ... Notches, 33 ... One-way clutch, 34 ... Encoder disk, 35 ... Slit, 36 ... LED, 37 ...
… Photo sensor, 38… Through hole, 39… Encoder, 47…
… Print window, 42 …… Ink ribbon guide window, 43 …… Slit, 44 …… Ink ribbon guide, 45 …… Hinge, 51
...... Control unit, 52 ...... Timing signal generation unit, 53 ...... Speed detection unit, 54 ...... Switch group, 55 ...... Temperature sensor, 56 ......
Amplifier, 57 …… A / D 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 …… V _REF2 generation circuit, 69 …… Select circuit, 72 …… Voltage follower, 73 …… First sample clock generation circuit, 74 …… Second sample clock generation circuit, 75 …… First sample hold Circuit, 76 ... Second sample and hold circuit, 79 ... V _REF1 generation circuit, 80 ... Latch circuit.

Claims (1)

(57) [Claims] 1. An output means for intermittently outputting a screen signal from an image sensor for reading data on an original surface, and an image signal output from this output means is binarized based on an integrated value of the image signal. First binarizing means, second binarizing means for binarizing the image signal output from the output generating means based on a single shresh voltage, and image signal output by the output means Output difference detecting means for detecting the difference between the image signals adjacent to each other, and the binarized signal of the first binarizing means when the output difference detected by the output difference detecting means is a predetermined value or more. A binarizing circuit for the image sensor output, comprising: selecting means for selecting the binarized signal of the second binarizing means when the selected output difference is equal to or less than a predetermined value.