JPH067620Y2 - Image forming device - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention digitizes and processes image information of an original,
The present invention relates to an image forming apparatus such as a digital type electronic copying apparatus which stores data on a thermosensitive recording paper, and particularly relates to an image forming apparatus having a reduction recording mode.

[Conventional technology]

In a digital electronic copying apparatus that digitizes and processes the image information of a document and records it on a thermal recording paper, in order to obtain a reduced recording smaller than the document, the held image information is read at the thinned sampling timing. To be

[Problems to be solved by the device]

When the remaining blank portion of the line generated by the sampling clocks thinned out in this way is written at the same timing, for example, when it is reduced to N / M times, it is compared with the same magnification. It will take twice as long.

Further, when preheating is applied to such a margin portion or the margin portion, the stroop width for preheating is short, so that there is a problem that the amount of heat for preheating is small and the temperature drops too much.

[Purpose of device]

The present invention has been made in view of the above problems, and has a simple circuit configuration in which the sampling timing of a blank portion generated by reduction is switched at high speed to reduce the total cycle time. It is an object of the present invention to provide a digital type electronic copying machine which can shorten and preheat temperature to an appropriate level.

[Means for Solving the Problems]

To achieve the above object, the gist of the present invention is to provide an image sensor unit for outputting image information of an original as an electric signal, a signal processing unit for encoding and processing the electric signal, and a main scanning direction. In a digital electronic copying apparatus, which has a large number of heating resistors arranged in a line, and a recording unit for receiving an image signal from the signal processing unit and printing on a thermal recording paper, reduction recording smaller than the original size is performed. Reduction recording mode selection means to obtain, a data sampling clock generation circuit in the reduction recording mode for generating thinned data sampling timing for reduction, and switching to a high-speed clock for margin data sampling, and during reading the previous line , A storage unit capable of writing data for the next line, and a preheating switch during reading the margin data. It lies in the fact that it generates a trobe.

[Action]

When the reduction recording mode is selected and the apparatus is started, the data sampling clock generation circuit initially outputs clocks with thinned timing corresponding to the reduction rate. Then, the remaining margin of the line generated by the reduction is written in the storage means at a high speed timing. The data is then sent to the recording unit at a high speed for recording, and the margins are preheated by the heating resistors by a short strobe signal for preheating.

[Example of device]

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

<Structure> First, the structure will be described.

As shown in FIG. 1, the digital electronic copying apparatus 10 includes an image sensor unit 100 for reading a document and converting it into an electric signal inside a box 11, and a character / image signal from the image sensor unit 100. A signal processing unit 200 that receives and processes the received image and a recording unit 500 that records the output image signal of the signal processing unit 200 on a thermosensitive recording paper are housed.

The box body 11 receives the AC power from the commercial power supply and houses the power supply unit 12 which constitutes a stabilized DC power supply of a plurality of levels.

On the other hand, on the upper surface of the box body 11, there is provided a document table 14 on which a document is placed and which is sent in the sub scanning direction by a document table motor 13 provided in the box body. The platen 14 includes a transparent plate 15 such as glass and a pressure plate 16 covering the upper surface thereof, and is driven by a platen motor 13 and a pulley 18 driven via a belt 17, and a rack-pinion mechanism 19. It

The image sensor unit 100 uses LE as an irradiation light source.
A photoelectric conversion unit including a D array 110, a lens array 120 that collects reflected light from a document, and a large number of photoelectric conversion elements 135.
It consists of 130 and.

The lens array 120 is composed of a large number of fiber lenses (rod lenses) arranged in a line.

The photoelectric conversion unit 130 constitutes the number of pixels. For example, if it is configured to have 8 pixels / millimeter, 1728 photoelectric conversion elements 135 for A4 size are arranged in the main scanning direction.

As the photoelectric conversion element 135, CdS or the like as a photoconductive effect type sensor that changes the conductivity of the element by light irradiation is used, but a photovoltaic effect type sensor such as a photodiode may be used.

The photoelectric conversion unit 130 is provided near one end of the lens array 120, and is a so-called contact type image sensor unit.
It is 100.

As shown in FIG. 2, the signal processing unit 200 includes a level adjusting unit 250 that adjusts the variation of each photoelectric conversion element 135 in the image sensor unit 100, the detected image information of the document and the non-image information (ground color). Envelope detection unit 260 for adjusting the contrast with the threshold level generation unit 270 that outputs the threshold level from the dither data and the density selection signal selected externally, and the sample hold unit 215. From the threshold level generation unit 270, and has a comparison unit 220 that encodes image information, these encoded image signals are equal magnification. Alternatively, a line memory 340 is provided for receiving via a magnification selection unit 320 and a serial / parallel conversion unit 330 for recording at an enlarged or reduced magnification. It has been.

Between the line memory 340 and the output to the recording unit 500, a parallel / serial conversion unit 370 that outputs the image signal in series,
A central print control unit 380 for centering the recorded image on the thermal paper when reduced recording is selected, an all-black preheat data generation unit 390 for providing all-black information for preheating, and the like are provided.

Further, while a central CPU of each functional unit of the signal processing unit 200 is arranged, a sampling timing generation unit 300 and a strobe width monitoring unit are provided from an original oscillation unit 205 that generates a reference clock for all operations of the device 10. A clock signal is issued to 420, the read timing generation unit 360, and the like.

Further, a strobe generating section 410 is provided for controlling the energization time to each heating resistor in the recording section 500.

The line memory 340 is further supplied with a signal from the normal / mirror image address generation unit 350, which indicates whether the recorded image is a normal image or a mirror image.

The main ones of the above-described respective component parts in the signal processing unit 200 will be described in more detail below.

As shown in the block diagram of FIG. 5, the data sampling timing generation unit 300 and the threshold generation unit 270 for obtaining the enlarged recorded image include a plurality of frequency dividers 301 and 302 for dividing the original oscillation clock and these frequency dividers 301 and 302. A counter 303 that switches the frequency dividers 301 and 302 and the like, a changeover switch unit 304, and the like.

On the other hand, the threshold level generation unit 270 receives the dither matrix from the dither data register 280.
D / A converter 27 that outputs the digital amount of dither data from
Have one.

As shown in FIG. 6, the normal / mirror image address generation unit 350 includes a 1/8 frequency divider circuit 355 of the basic clock, a normal image side counter 351, a bus switch 352, and a mirror image side counter 35.
3 and the parallel / serial conversion unit 370, which is composed of the bus switch 354 and receives the output data from the line memory 340 which is the storage unit, is also the normal image side shift register 3
71 and a mirror image side shift register 372.

The front and rear counters 351, 353, the bus switches 352, 354, and the parallel / serial conversion unit 370 are reading means.

Next, FIG. 7 shows a configuration on the reduction scale side in the scale selection unit 320.

In this example, as shown in the figure, the case of reducing to 2/3 is shown, and the reduction ratio selecting unit 321 thins out the basic sampling clock generated from the basic sampling clock generating unit 210 to 2/3. Reduced clock generator 322
And counting the basic sampling clock, all bits of one line, for example, 2/3 of 1728, that is,
Counter 32 that outputs when counting 1152 bits
3 and the output from this counter 323, the inverter
Through the 326, during the active H period, the first AND gate 324 that outputs the reduced clock of the reduced clock generation unit 322 and the second AND gate 325 that outputs the high-speed basic sampling clock by the H signal of the counter 323.
And an OR gate 327 that outputs a logical sum of the first and second AND gates 324 and 325, a counter 328 for detecting the count-up of all bits, and a third AND
It consists of gate 329 etc.

FIG. 8 shows the configuration of the central print control unit 380 that shifts the recording to the center of the paper when the reduction ratio (2/3) as described above is selected. Note that FIG. 8 shows only the normal image side.

Also, since the reduction is 2/3, the total of 216 bytes (1728/8) is 2
/ 3, that is, 144 bytes of recording are controlled to be positioned closer to the center. Therefore,
72 bytes out of 216 bytes are blank, and the blank part 7
A half of 2 bytes, that is, 32 bytes, is blank in the main scanning direction from the edge of the paper.

Therefore, the central print control unit 380 outputs a logical product of a counter 381 that counts and outputs the 36 bytes and an output signal of the counter 381 and the basic clock signal.
ND gate 382 and NAND gate (A that outputs the remaining 180 bytes excluding 36 bytes and outputs active L)
ND gate + inverter) 383 and this NAND gate 3
It consists of a second AND gate 284 which outputs a basic clock during the input period of 180 bytes of 83 and sends a clock for outputting data from the shift register 371.

A latch 385 for holding the 37th byte and subsequent signals is provided on the output side of the counter 381.

As shown in FIG. 9, the strobe generating section 410 has a CPU 4
N ₁ counter pulses f from 00 (4 in this embodiment)
Pulse) and a counter A411 that counts and outputs
This counter A411 has N ₂ counts (same 4 counts)
A counter B412 that counts and outputs the total count N ₁ × N ₂ (4 × 4 = 16 counts)
It comprises a demultiplexer 413 for transmitting and switching the (four) strobe signals STB1 to STB4.

The strobe widths of the strobe signals STB1 ... Change depending on the width of the original pulse f, and the change of the original pulse f is configured by the software of the CPU 400. Next, the strobe generator 410
Strobe width monitoring unit that monitors the strobe in connection with
As shown in FIG. 10, 420 is a counter C421 that counts F6 at the same time as the strobe is generated from the demultiplexer 413 and transmits a signal when a predetermined number of pulses is reached,
This output signal is held and transmitted to the demultiplexer 413, the latch 422 for inhibiting the strobe signal, the latch B423 for latching the N ₁ count of the counter A411, the output (X) of this latch B423, or the demultiplexer 413 It is composed of an OR gate 424 which clears the counter C421 by any of the output signals (Y).

In FIG. 9, a strobe generator 410, which is omitted in FIG. 9, is provided with a latch A414 for latching a strobe start signal and an AND gate A415 for passing a pulse signal of CO0 by the latched signal. There is.

Next, the recording unit 500 will be described.

The recording unit 500 applies heat energy to heat-sensitive paper in response to an image signal, mainly a Sahemal head 550 that obtains a recorded image, a platen roller 501 that pushes the heat-sensitive paper against the Sahemal head 550, and the fed sheet. It is composed of a feed roller 502 for feeding a sheet.

A paper feed switch 503 for sending a paper feed signal is provided in front of the feed roller 502, and a discharge side of the platen roller 501 is provided with
A paper discharge switch 504 is provided.

Inside the box body 11, there is provided a roll paper shaft 505 for roll-shaped thermal paper.

The platen roller 501 is configured to be driven in the sub scanning direction by a platen motor (stepping motor) 506 via a belt 507.

As shown in FIG. 11, the thermal head 550 is formed by arranging a large number of heating resistors 551 that form the number of pixels in the main scanning direction on one surface of a radiator 552 such as aluminum, and the surface thereof is a glass insulator. Covered with 553.

The heating resistor 551 has, for example, 8 pixels / millimeter, and 1728 A4 sizes are arranged. Furthermore, dummy heating resistors for compensating the imbalance of the heat generation amount are provided at both ends, respectively. Are added one by one.

The heat generating resistors 551 in the thermal head 550 are grouped into a plurality of blocks as a whole, and FIG. 12 shows a block diagram of each block.

Each heating resistor 551 has one end connected to the recording power supply line 555 and the other end connected to a control switch group 556 that opens and closes in accordance with an image signal from the line memory 340 of the signal processing unit 200.
Then, a strobe signal gate 557 is provided for each block.
have.

The thermal head 550 is provided with a temperature detecting thermistor (not shown) for detecting the heat generation temperature.

<Operation> In the above configuration, this device operates as follows.

(Preparation for copying) The original is placed on the original table 14 and the power switch of the power supply unit 12 is turned on. In this state, the line memory 340 generates an all-black preheat generation signal, and the thermal head 550 is preheated to a predetermined temperature.

The supplied thermal paper for recording includes a sheet fed from the front side of the feed roller 502 and a roll paper pre-loaded on a roll paper shaft 505 provided at the rear part of the platen roller 501. There is.

The thermal paper is formed by coating a color-developing layer on one surface of the base paper, and as the color-developing layer, for example, a leuco dye and a phenol compound, which are dispersed in a binder, are used. The binder melts and the leuco dye and the phenol compound come into contact with each other to develop color.

Normal paper is used as the base paper of the roll paper, but transparent resin is used as the base paper of the sheet, and a header of normal paper to which the coloring layer is not applied is attached to the leading end.

In FIG. 1, the sheet is inserted between the platen roller 501 and the feed roller 502 through the paper feed switch 503, and when the sheet feed switch 503 receives the signal, the platen motor 506 is driven.
Starts and the thermal paper is fed. At this time, in the signal processing unit 200, by the action of the positive / mirror image address generation unit 350,
The mirror image address generation side is selected. Then, the obtained recorded image is seen as a normal image when viewed from the back surface of the base paper of the thermal paper, that is, the side not coated with the color forming layer.

The sheet sent along the platen roller 501 passes between the sheet and the thermal head 550, and when the header portion of the sheet edge is detected by the sheet discharge switch 503, the platen motor 506.
Moves the header portion directly below the thermal head 550, and moves back and forth several times at this position, and then returns to the position of the paper discharge switch 504 to complete the preparation.

In the forward / backward movement, the print residue attached to the surface of the insulator 553 covering the surface of the heating resistor 551 of the thermal head 550 is rubbed off by the header portion of the thermal paper.

In the case of roll thermal paper, since the paper feed switch 503 does not act, when the paper edge reaches the paper discharge switch, preparation is completed as it is, and the normal / mirror image address generation unit 350 selects the normal image side.

(Recording Operation) At the same time as the above-mentioned preparation operation is completed, the apparatus 10 starts the recording operation.

In the recording operation, the document table 14 is sent in the sub-scanning direction, the image sensor unit 100 scans the document in the main-scanning direction and sends out image information, while the signal processing unit 200 processes these image information. And sends it to the recording unit 500.

In the recording section 500, the thermal paper is normally synchronized with the platen and the image signal is recorded while being sent in the sub-scanning direction.
Particularly in the case of recording reduced in the sub-scanning direction, that is, so-called fine mode recording, the image is fed at the sub-scanning feed speed corresponding to the reduction ratio.

The main operations of these recording operations will be described below.

(Sub-scan feed amount and strobe width control operation) When fine mode recording is selected in the recording operation, the thermal paper is fed with a small feed amount in the sub-scan direction. In such fine mode recording, for example, when an A4 size document is sent as 2/3, a substantially square recording is obtained, and it is used as it is as an OHP document on an OHP square document table equipped with a Fresnel lens. Can be done.

In fine mode recording, if the thermal head 550
When the normal energization is performed, the pixels in the front row and the pixels in the rear row overlap each other as shown in FIG. 13A, and the obtained entire image has a desired density or more.

Therefore, as shown in FIG. 9, in the fine mode recording, the counter pulse (f) is reduced by software and each strobe signal width, STB1 to STB4, is reduced in proportion to the sub-scanning amount of the thermal paper. , As shown in FIG. 13B, the recording density is made constant by eliminating the overlap.

That is, by reducing the strobe width in proportion to the sub-scan feed amount, as in the present apparatus 10, FIG.
Compared with this, the recording pixels in FIG. 13B are smaller, and there is no overlap between the front and rear lines.

(Strobe width monitoring operation) As shown in FIG. 12, the strobe signal is given to each block of the heating resistor 551 of the thermal head 550, and the image signal is given by the signal from the line memory 340. The energization time of the pixel is controlled.

In the normal case, each strobe signal switches for each block and shifts to the strobe signal of the next stage, but if a certain strobe signal becomes larger than the predetermined time width, it will be automatically Strobe signal is prohibited, and thermal paper does not record.

That is, in FIG. 10, the counter pulse signal CO
0 is taken into the counter A411 by the signal of the latch A414 generated by the strobe start signal 0ST and transmitted every four counts, and the counter B412 transmits this every four counts. Then, as shown in FIG. 10, the demultiplexer 413 sequentially outputs four strobe signals STB1 to STB4, but the signal of F6 is counted by the counter C421, and this is the STB1 to STB4. When counting to a predetermined count, which is greater than any of the above, it is output to the latch C422, and the demultiplexer 4 is output via this latch C422.
A prohibition signal is issued to 13.

(Enlargement Recording Operation) In the magnification selection unit 320, for example, as shown in FIG. 5 showing the case where 3/2 times enlargement recording is selected, a double speed sampling timing signal is issued once every three times. That is, the same image signal is output once every three times, and the recording is expanded by this amount.

However, if the image information thus overlapped is encoded by comparing it with a constant threshold level as it is, the obtained recorded image becomes awkward with variations in shade.

Therefore, as shown in FIG. 5, the dither data stored in the dither data register 280 is transmitted from the predetermined dither data matrix at each sampling timing, and the D / A converter 271 outputs one dither data. The level is sent to the comparison unit 220. Such a threshold level is held to provide a random comparison value to the duplicated data, give unevenness to the coding of the duplicated data as a whole, and obtain a recorded image having a pseudo halftone. .

(Enlargement recording operation) The operation of reducing the vertical scanning direction of the recorded image by reducing the sub-scan feed amount of the thermal paper has already been described.
At 320, in order to obtain reduced recording in the main scanning direction, unlike the reduction in the sub-scanning direction, it is obtained by thinning out data in the main scanning direction.

Therefore, the reduction recording operation for reducing to 2/3 will be described with reference to FIG. 7. The basic sampling clock is thinned out by 1/3 by the reduction clock generation unit 322 and sent to the first AND gate 324.

Since the output from the counter 323 is input to the first AND gate 324 via the inverter 326, the counter 3
23 becomes H input until 2/3 of the total count 1728, that is, 1152 counts, and the reduced clock generation unit 32
The output from 2 is directly output from the first AND gate 324.

Then, at the 1153th count, the L signal is output from the inverter 326, and the input from the reduced clock generation unit 322 is cut. That is, after that, it becomes an all-white signal.

On the other hand, the second AND gate 325 has a high-speed clock signal,
Since the output signal of the counter 323 is input, from the 1153th count onward, a high-speed clock is output from the second AND gate 325 and input to the OR gate 327.

That is, from the OR gate 327, the reduced clock decimated to 2/3 is transmitted up to 1152 counts, and after the 1153th count, the high speed clock is transmitted and output through the third AND gate 329.

On the other hand, the output of the OR gate 327 is also input to the counter 328, and is inverted and output when the thinned-out signal and the high-speed signal have been counted for 1728. Therefore, the third AND gate 329 is closed and one line Sampling clock is completed.

In this way, the sampling of the blank area is performed at high speed, so that the entire recording operation is speeded up.

(Normal / Mirror image recording operation) With this device 10, it has already been described that a normal image is automatically selected for roll thermal paper, and a mirror image recording is automatically selected for sheet thermal paper. Next, referring to FIG. The operation of will be described.

The encoded image signal is sent to the serial / parallel converter 33.
The byte address is transferred to the line memory 340 via 0 and the byte address is transferred to the line memory 340 via the normal image counter 351 or the mirror image counter 353. Then, in the case of a normal image by selecting either the normal image or the mirror image, the recording unit 500 from the line memory 340 through the shift register 371.
In the case of a mirror image, it is also transmitted via 372.

Since the image signal is transmitted for each byte, in the case of a mirror image, the order within each byte as well as each byte itself
The images are taken out in the reverse order to the case of the normal image.

(Central printing control operation) This is not a problem when only normal image recording is used, but with this device that can obtain a normal image and a mirror image, especially in the case of a mirror image, when viewing the actually recorded image, You have to look at the right image.

In the above case, especially when the reduced recording image is biased to one side of the paper surface, when viewed from the back side of the paper, the image position appears to move to the left and right, which causes a feeling of strangeness.
It is recorded near the center of the page.

The case of a normal image reduced to 2/3 will be described with reference to FIG. 8. 216 × 1/3 = 72 bytes out of the total of 216 bytes become blank, and by dividing this blank portion into left and right by 36 bytes, The recorded image will be located at the center.

Therefore, as shown in FIG. 8, the first AND gate 382 is closed by the L signal of the counter 381 that does not output up to 36 bytes, and is taken into the counter 351 from the 37th byte.

On the other hand, the clock signal of the shift register 371 for reading the signal from the line memory 340 passes through the second AND gate 384, and the second AND gate 384 subtracts 36 bytes for the front blank from the total 216 bytes. Since it is input together with the NAND gate 383 which outputs only 180 bytes, the shift register (parallel / serial conversion unit)
The 371 will thereafter start sending data. There is no problem because the blank 36 bytes in the latter half is read as blank data.

[Effect of device]

The digital electronic copying apparatus according to the present invention has a reduced recording mode, and when this mode is selected, sampling clocks thinned corresponding to the reduction ratio are generated, and the margin is converted to a high-speed clock. It has a data sampling clock generation circuit that switches and a storage means that can write and read for each line, and generates a preheat strobe signal during blank space data reading. Can be shortened, and the heating resistor in the recording section can always be kept at an appropriate temperature level.

[Brief description of drawings]

1 to 13 show an embodiment of the present invention, and each drawing shows the following. FIG. 1 is a side structural view of the image forming apparatus, FIG. 2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is an explanatory view of the structure of a document table, and FIG. 5, FIG. 5 is a block diagram of a sampling timing generation circuit for an enlarged image and a threshold level generation unit, FIG. 6 is a writing / reading circuit diagram of a positive / mirror image, and FIG. 7 is a sampling clock generation circuit diagram at the time of reduction. , FIG. 8 is a circuit diagram for central print control (in the case of a normal image), FIG. 9 is a strobe generating circuit diagram, and FIG.
FIG. 0 is a block diagram of the strobe width monitoring unit, FIG. 11 is a perspective view of the thermal head, FIG. 12 is a configuration diagram of the thermal head, and FIG. 13A is a recording pixel at the time of reduction in the sub-scanning direction without strobe width control. 13 is an explanatory view of the action of the overlapping
FIG. B is an operation explanatory view showing a recording pixel when strobe width control is performed corresponding to sub-scan feed.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04N 1/393 4226-5C

Claims (1)

[Scope of utility model registration request] 1. An image sensor unit for outputting image information of an original as an electric signal, a signal processing unit for encoding and processing the electric signal, and a large number of heating resistors arranged in the main scanning direction. In the image forming apparatus, a reduction recording mode selecting unit for obtaining a reduction recording smaller than a document size, and a thinning-out for thinning, in an image forming apparatus, comprising a recording unit for receiving an image signal from the signal processing unit and printing on a thermal recording paper. The data sampling clock generation circuit for the reduced recording mode, which generates the data sampling timing and switches to the high-speed clock for blank space data sampling, and the storage means capable of writing the data for the next line while reading the previous line. Image forming, wherein a strobe for preheating is generated during the reading of the margin data. Location.