JP2000267540A - Image forming device and its controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely generate a start timing of an image forming corresponding to plural processing speeds using a simple circuit constitution. SOLUTION: An image forming device conducts an image forming on a recording medium which is being carried with the speed corresponding to a processing speed that is set. A clock CLKS having a period corresponding to the set processing speed is generated by an eleven bit counter 401, a processing speed setting register 402 and a selector 403. The generated clock CLKS is counted by an eighteen bit counter 404 and the start timing of an image forming is determined by a comparator 405, an image forming start register 406 and a JK flip-flop 410 based on the counted value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus capable of forming an image on a recording medium conveyed at a speed corresponding to a set process speed, and a method of controlling the image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus having a plurality of process speeds, as a means for generating an image forming start timing, a single basic clock is used from a signal (for example, a registration roller ON signal) related to the position of a sheet. Has been used, and a means for comparing the count value with a preset register value has been used.

The conventional image forming apparatus has a plurality of registers and is configured to store a comparison value corresponding to each process speed.

[0004]

However, in the above-described conventional image forming apparatus, a plurality of registers corresponding to each process speed must be provided, and the circuit configuration is complicated.
In addition, there is a problem that the scale becomes large.

[0005] Further, there has been an apparatus in which a register corresponding to each process speed is shared by one register and rewritten to a comparison value corresponding to each process speed. In a device that can be changed to a 2-speed or 1 / 4-speed, it is necessary to increase a counter for counting clocks by 2 bits as compared with a device having a constant process speed.
There is a problem that the circuit configuration is complicated and large.

Further, when a single register is used for a register corresponding to each process speed, the register must be rewritten every time the process speed is changed, and the control procedure is complicated and complicated. However, there is also a problem that the control program becomes obscured.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the first to fifth inventions according to the present invention is to convey a sheet at a speed corresponding to a set process speed. In an image forming apparatus capable of forming an image on a recording medium, a clock having a cycle corresponding to the set process speed is generated, the generated clock is counted, and an image is generated based on the counted value. It is an object of the present invention to provide an image forming apparatus and a control method of the image forming apparatus, which are capable of accurately generating an image forming start timing corresponding to a plurality of process speeds with a simple circuit configuration by determining the formation start timing. .

[0008]

According to a first aspect of the present invention, a process speed to be set (operation unit 3 shown in FIG. 1) is set.
2 through the I / F unit 313 or based on the type of recording medium such as plain paper, cardboard, or OHP sheet.
The standard speed set by the CPU 291 shown in FIG.
Generating means for generating a clock having a cycle corresponding to the set process speed in an image forming apparatus capable of forming an image on a recording medium conveyed at a speed corresponding to the process speed (1/4 speed, 1/4 speed). The 11-bit counter 401 and the process speed setting register 40 shown in FIG.
2, selector 403) and first counting means (18 shown in FIG. 4) for counting the clock generated by the generating means.
A bit counter 404) and first determining means (a comparator 405, an image forming start register 406, and a JK flip-flop 410 shown in FIG. 4) for determining an image forming start timing based on the count value of the first counting means. It has.

According to a second aspect of the present invention, the first determining means determines the count value of the first counting means and a predetermined value (the value stored in the image forming start register 406 shown in FIG. 4). For example, “6CB4 (hexadecimal notation)” shown in FIG. 5)
The image forming start timing is determined based on the result of the comparison.

In a third aspect of the present invention, a second counting means (14-bit counter 408 shown in FIG. 4) for counting the number of main scanning lines and a sub-counter based on the count value of the second counting means are provided. It has second determining means (a comparator 409, an image forming section register 408, and a JK flip-flop 410 shown in FIG. 4) for determining an image forming section in the scanning direction.

According to a fourth aspect of the present invention, a color component image formed by an image forming section for each color component arranged side by side is recorded on a recording medium conveyed at a speed corresponding to a set process speed. In an image forming apparatus capable of forming a multi-color image by superimposition, generating means (an 11-bit counter 401 and a process speed setting register 4 shown in FIG. 4) for generating a clock having a cycle corresponding to the set process speed.
02, selector 403) and counting means for each color component for counting the clock generated by the generating means (in the image forming start timing signal generating section shown in FIG. 4 provided in each of the delay sections 202 to 205 shown in FIG. 3). 18-bit counter 404), and color component determining means (delay units 202 to 205 shown in FIG. 3) for determining the image formation start timing for each color component based on the count value of the color component counting means.
And a comparator 405, an image formation start register 406, and a JK flip-flop 410 in the image formation start timing signal generator shown in FIG.

A fifth invention according to the present invention relates to a method for controlling an image forming apparatus capable of forming an image on a recording medium conveyed at a speed according to a set process speed,
A generating step for generating a clock having a cycle corresponding to the set process speed (step (1) in FIG. 6), a counting step for counting the generated clock (step (3) in FIG. 6); (Steps (4) and (5) in FIG. 6) for determining the image formation start timing based on the counted value.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 shows an LED to which an image forming apparatus according to a first embodiment of the present invention can be applied.
FIG. 2 is a cross-sectional view illustrating the configuration of a binary recording digital color copying machine using an array (600 dpi) as an exposure system, in which a reader unit 1 is arranged at an upper part and a printer unit 2 is arranged at a lower part.

In the reader unit 1, reference numeral 301 denotes a platen glass (platen) which is provided horizontally above the color reader unit. Reference numeral 302 denotes a document feeder (DF),
1, and sequentially feeds the originals placed on an original table (not shown) to a platen 301. There is also a configuration in which a mirror pressure plate (not shown) is mounted in place of the document feeding device 302.

Reference numeral 314 denotes a first carriage, in which light sources 303 and 304 such as halogen lamps or fluorescent lamps, and a reflector 30 for condensing the light from these light sources 303 and 304 on a document.
5 and 306, and a mirror 307 that reflects light reflected or projected from the document.

Reference numeral 315 denotes a second carriage, in which mirrors 308 and 309 for reflecting the reflected light from the mirror 307 to the CCD 101 are accommodated. 3
Reference numeral 10 denotes a lens which collects reflected light from the mirrors 308 and 309 on the CCD 101.

The CCD 101 has mirrors 307, 308, 3
09, the reflected light or the projected light of the original input through the lens 310 is converted into an electric signal. In the case where the CCD 101 is a color sensor, even if the RGB color filters are inlined in RGB order on one line CCD,
3 line CCD, R filter, G filter,
The B filter may be arranged for each CCD, or the filter may be on-chip, or the filter may be configured differently from the CCD.

Reference numeral 311 denotes a base on which the CCD 101 is mounted. Reference numeral 312 denotes a digital image processing unit (hereinafter, referred to as an image processing unit), which includes components other than the CCD 101 shown in FIG. 2 described below, a binary conversion unit 201, delay units 202 to 205, a CPU 291 and a ROM 292 shown in FIG. , RA
M293 and an image formation start timing signal generation unit shown in FIG.
The overall control of the copying machine is performed based on the program stored in the printer.

Reference numeral 313 denotes an interface (I / F).
The other IPU (Image Processing)
Unit), an interface with an external device or the like.
Image information input by the I / F unit 313 from an external device such as a host computer via a predetermined communication medium is transferred to an image processing unit 312, and an image can be formed by a printer unit. Also, from an external device such as a host computer via the I / F unit 313, the number of recorded sheets, plain paper,
Type of recording medium such as cardboard, OHP sheet, standard speed, 1 /
Various settings such as a process speed such as a second speed and a quarter speed, and various image forming modes can be performed.

The first carriage 314 moves at a speed V,
The second carriage 315 scans (sub-scans) the entire surface of the document at a speed V / 2 by mechanically moving the driving unit 316 in a direction perpendicular to the electrical scanning (main scanning) direction of the CCD 101. .

An operation unit 300 includes various keys (not shown) and a display unit such as an LCD. The number of records, the type of recording medium such as plain paper, thick paper, and OHP sheet, the standard speed, and 1/2.
Various settings such as a process speed such as a speed, a quarter speed, and various image forming modes can be performed.

Further, the operation unit 300 or the I / F unit 31
3, the number of recordings, plain paper, thick paper, OH
Type of recording medium such as P sheet, standard speed, 1/2 speed, 1 /
Various setting information such as a process speed such as the fourth speed and various image forming modes are transmitted to the image processing unit 312 and stored in a non-illustrated non-volatile memory in the image processing unit 312. In addition, the CPU 291 in the image processing unit 312 determines the standard paper for plain paper based on the type of recording medium such as plain paper, thick paper, or OHP sheet set via the operation unit 300 or the I / F unit 313. Speed, 1/2 speed for cardboard, O
In the case of an HP sheet, it is also possible to configure so that the process speed of 1/4 speed is automatically set.

Further, a sensor for detecting an OHP sheet to be fed is provided. When the sensor detects an OHP sheet, the CPU 291 in the image processing unit 312 automatically sets a 1/4 speed process speed. It is also possible to configure.

In the printer section 2, 317, 318,
Reference numerals 319 and 320 denote yellow (Y) image forming units, magenta (M) image forming units, cyan (C) image forming units, and black (K) image forming units, respectively.
3,344,345, primary chargers 321,324,32
7, 330, LED unit (LED array) 210, 21
1, 212, 213, developing units 322, 325, 328,
331 and the like.

Further, the developing devices 322, 325, 328, 3
Reference numeral 31 includes developing sleeves 355, 356, 357, and 358 for applying a developing bias to perform development.

The yellow (Y) image forming section 317,
Since the respective configurations of the magenta (M) image forming section 318, the cyan (C) image forming section 319, and the black (K) image forming section 320 are the same, the yellow (Y) image forming section 31
7 will be described in detail, and description of other image forming units will be omitted.

The primary charger 321 uniformly charges the surface of the photosensitive drum 342 and prepares for formation of a latent image. The LED unit (LED array) 210 is provided with a photosensitive drum 342 by light.
A latent image is formed on the surface of the substrate. The developing device 322 forms a toner image by developing a latent image formed on the surface of the photosensitive drum 342.

Reference numeral 323 denotes a transfer charger, which is disposed below the developing device 322 with the transfer belt 333 interposed therebetween, discharges electricity from the back of the transfer belt 333, and transfers the toner image on the photosensitive drum 342 to the transfer belt 333. To a recording medium such as recording paper. In the present embodiment, the transfer efficiency is good, and thus the cleaner is not provided, but it goes without saying that there is no problem even if the cleaner is mounted.

338 and 339 are pickup rollers.
Recording media such as recording paper stored in the cassettes 340 and 341 are fed one by one. Reference numerals 336 and 337 denote registration rollers (feed rollers) which supply the recording medium fed by the pickup rollers onto the transfer belt 333 which moves. The paper feed rollers 336 and 337 temporarily stop the recording medium (transfer material) fed by the pickup rollers 338 and 339, and turn on a registration roller clutch (not shown) at a predetermined timing to transfer the recording medium (transfer material). Is supplied onto the transfer belt 333.

Reference numeral 348 denotes a transfer belt roller, which is a yellow (Y) image forming unit 317 and a magenta (M) image forming unit 3
18, cyan (C) image forming section 319, black (K)
The transfer belt 333 is disposed below the image forming unit 320.
Is driven, and the recording medium such as the recording paper is charged in a pair with the adsorption charger 346 to cause the transfer belt 333 to adsorb the recording medium such as the recording paper.

Reference numeral 347 denotes a paper edge sensor, which is a transfer belt 33.
3 detects the leading edge of the recording paper fed. The detection signal of the paper leading edge sensor 347 is transmitted from the printer unit 2 to the reader unit 1.
The signal is sent to the delay units 202 to 205 in the reader unit 1 shown in FIG. 3 to be described later. The image forming timing signal generation unit shown in FIG.
It is used to generate C and K image formation timing signals. The image forming timing signal is used as a sub-scanning signal when a video signal is sent from the reader unit 1 to the printer unit 2.

Reference numeral 349 denotes a static eliminator, which neutralizes the recording paper and the like that has passed through the black (K) image forming section 320 to facilitate separation of the recording paper and the like from the transfer belt 333. Reference numeral 350 denotes a peeling charger, which is provided adjacent to the charge removing charger 349 to separate recording paper and the like from the transfer belt 333 and prevent image disturbance due to peeling discharge when the recording paper and the like separate from the transfer belt 333. .

Reference numerals 351 and 352 denote pre-fixing chargers for charging recording paper and the like, supplementing the toner attraction force, and preventing image disturbance. A fixing device 334 thermally fixes the toner image on the recording paper after being charged by the pre-fixing chargers 351 and 352, and discharges the toner image to a discharge tray 335.

FIGS. 2 and 3 show the image processing unit 3 shown in FIG.
FIG. 12 is a block diagram showing a configuration of a twelfth embodiment.

In FIG. 2, reference numeral 102 denotes a clamp & Am
p. In the & S / H & A / D section, the electric signal (analog image signal) converted from the reflected light of the original by the CCD 101 is sampled and held (S / H), the dark level of the analog image signal is clamped to the reference potential, and (The above processing order is not limited to the notation order), A / D converted, and converted into, for example, a digital signal of 8 bits for each of RGB.

Numeral 103 denotes a shading portion, which includes a clamp & Amp. R input from & S / H & A / D unit 102
Shading correction and black correction are performed on the GB signal. 10
Reference numeral 4 denotes a connection & MTF correction & original detection unit.
In the case of a three-line CCD, the splicing process differs in the reading position between the lines. Therefore, the delay amount for each line is adjusted according to the reading speed, and the signal timing is corrected so that the reading positions of the three lines become the same. Further, the MTF correction by the connection & MTF correction & original detection unit 104 corrects the change because the reading MTF changes depending on the reading speed and the magnification. Further, the original detection by the connection & MTF correction & original detection unit 104 recognizes the original size on the original platen glass.

Reference numeral 105 denotes an input masking unit,
The spectral characteristics of the CCD 101 and the spectral characteristics of the light sources 303 and 304 and the reflectors 305 and 306 are corrected for the digital signal whose read position timing has been corrected by the TF correction and document detection unit 104. The output of the input masking unit 105 is input to the selector 106 that can be switched with the external I / F unit 114.

Reference numeral 115 denotes a background removal unit that removes the background of the signal output from the selector 106. Reference numeral 116 denotes a black character determination unit which determines whether or not the document is a black character of the document, and generates a black character signal from the document.

Reference numeral 107 denotes a color space compression & background removal & LOG conversion unit which includes a color space compression unit, a background removal unit, and a LOG conversion unit. The color space compression unit enters a range where the read image signal can be reproduced by the printer. It is determined whether or not the image signal is present, and if not, correction is made so that the image signal falls within a range that can be reproduced by a printer. Then, the background removal unit performs background removal processing, and the LOG conversion unit converts the RGB signals into CMY signals by LOG conversion.

Reference numeral 108 denotes a delay unit that adjusts the timing of the output signal of the color space compression / background removal / LOG conversion unit 107 to correct the timing and the signal generated by the black character determination unit 116. Reference numeral 109 denotes a moiré removing unit that removes moiré of the two types of signals (the signal generated by the black character determination unit 116 and the output signal of the color space compression / background removal / LOG conversion unit 107 for correcting timing). Reference numeral 110 denotes a scaling unit which performs scaling processing in the main scanning direction.

Reference numeral 111 denotes a UCR & masking & black character reflecting unit which is composed of a UCR unit, a masking unit and a black character reflecting unit. The UCR unit performs a UCR process on the CMY signal processed by the scaling unit 110 to generate a CMYK signal. The masking unit corrects the signal to the output of the printer, and the black character reflection unit converts the determination signal generated by the black character determination unit 116 to CMYK.
Feed back to the signal.

Reference numeral 112 denotes a γ correction unit for adjusting the density of the signal processed by the UCR & masking & black character reflection unit 111. A filter unit 113 performs smoothing or edge processing and outputs the result to the binary conversion unit 201.

The signal processed as described above is converted from an 8-bit multi-level signal into a binary signal by a binary converter 201 shown in FIG. This conversion method may be any one of the improved dither method, error diffusion method, and error diffusion.

In FIG. 3, a binary conversion unit 201 binarizes a signal from the filter unit 113 (or the external I / F unit 114).

Reference numerals 202, 203, 204, and 205 denote delay units each internally (or externally) provided with an image formation start timing signal generation unit shown in FIG. 4 described later, and are generated by the image formation start timing signal generation unit. Using the image formation start timing signal as a sub-scanning synchronization signal, the image signal binarized by the binary conversion unit 201 is adjusted so as to adjust the difference in the distance between the paper edge sensor 347 and the image formation position of each color of YMCK. Delay each. That is, a binarized image signal is sent to the printer unit in synchronization with an image forming timing signal (sub-scanning enable ENBN shown in FIG. 4 described later). This makes it possible to print four colors of YMCK at predetermined positions. 206, 2
Reference numerals 07, 208, and 209 denote LED driving units,
LED units 210, 211, 212, and 2 according to image signals output from
13 is generated.

The CPU 291 controls the entire copying machine on the basis of a program stored in the ROM 292. The RAM 293 is used as a work area of the CPU 291. Further, the CPU 291 sets a process speed for each delay unit.

The operation of each section will be described below.

First, the original on the platen glass is a light source 30.
3, 304, and the reflected light is reflected by the CCD 10
1 and converted into an electric signal.

Then, the electric signal (analog image signal) is input to the image processing unit 312, and the clamp & Am
p. & S / H & A / D unit 102 sample and hold (S
/ H), the dark level of the analog image signal is clamped to the reference potential, amplified to a predetermined amount (the processing order is not limited to the notation order), A / D converted, and, for example, RGB.
It is converted into an 8-bit digital signal.

The RGB signals are output to the shading unit 1.
03, after shading correction and black correction are performed,
In the connection & MTF correction & document detection unit 104, the CCD 10
If 1 is a 3-line CCD, the splicing process differs in the reading position between the lines. Therefore, the delay amount for each line is adjusted according to the reading speed, and the signal timing is corrected so that the reading positions of the three lines become the same. In the MTF correction, the reading MTF changes depending on the reading speed and the magnification, so that the change is corrected, and the document detection recognizes the size of the document on the platen glass.

The digital signal whose reading position timing has been corrected is input to the CCD 101 by the input masking unit 105.
And the light sources 303 and 304 and the reflector 305,
The spectral characteristic of 306 is corrected. Input masking unit 105
The output of selector 1 is switchable to external 1 / F signal.
06.

The signal output from the selector 106 is subjected to color space compression, background removal & LOG conversion 107 and background removal 1
15 is input. After the signal input to the background removal unit 115 is removed from the background, the signal is input to a black character determination unit 116 that determines whether or not the document is a black character in the document, and a black character signal is generated from the document. Also, another selector 106
In the color space compression & background removal & LOG conversion unit 107 to which the output of (1) is input, the color space compression determines whether or not the read image signal is within the range that can be reproduced by the printer. In this case, the correction is made so that the image signal falls within a range that can be reproduced by the printer. Then, a background removal process is performed, and the RGB signals are converted into CMY signals by LOG conversion.

Color space compression, background removal, and LOG to correct the signal and timing generated by the black character determination unit 116
The output signal of the conversion unit 107 is adjusted in timing by the delay unit 108. The two types of signals are subjected to moiré removal by the moiré removal unit 109 and then subjected to scaling processing in the scaling unit 110 in the main scanning direction.

CMY processed by scaling unit 110
The signal is converted to a CMYK signal by the UCR processing unit in the UCR & masking & black character reflection unit 111, corrected to a signal suitable for the output of the printer by the masking processing unit, and generated by the black character determination unit 116 in the black character reflection unit. The judgment signal is fed back.

UCR & Masking & Black Character Reflection Unit 111
Is subjected to density adjustment by the γ correction unit 112 and then subjected to smoothing or edge processing by the filter unit 113.

Next, the signal from the filter unit 113 is binarized by a binary conversion unit 201, and the delay units 202, 203, and 2
04, 205.

Thereafter, the binarized image signal is sent to the delay units 202, 203, 204, and 205 by an image formation start timing signal (sub-scan shown in FIG. 4 to be described later) generated by the image formation start timing signal generation unit. Enable ENBN) as a sub-scanning synchronization signal,
7 is delayed so as to adjust the difference between the distance between the image forming position 7 and each image forming position (in synchronization with an image forming timing signal (sub-scan enable ENBN shown in FIG. 4 described later)), and
The data is sent to the ED driving units 206, 207, 208, and 209. LED drive units 206, 207, 208, 209 are L
A signal for driving the ED units 210, 211, 212, and 213 is generated.

The image forming start timing signal generator corresponding to the process speed, which is a feature of the present invention, will be described below.

First, the necessity of having a plurality of process speeds will be described.

In the image forming apparatus such as a digital color copying machine shown in FIG. 1, the process speed must be changed depending on the recording medium. The reason is mainly due to the difference in the fixing characteristics of each recording medium. When the recording medium is thick paper, etc., the thick paper absorbs more heat of the fixing unit than plain paper.Thus, when the fixing medium is passed through the fixing unit at the same process speed as plain paper, the heat of the fixing roller decreases and the recording medium , The fixability of the toner deteriorates.

When the recording medium is an OHP sheet or the like,
When the toner passes through the fixing device at the same speed as that of plain paper, the toner is not completely melted, and the light transmittance is poor. Therefore, FIG.
In the digital color copying machine shown in FIG. 1, the process speed of plain paper is set to a standard speed (in the present embodiment, about 116.869).
4 mm / s), and the process speed of the cardboard is 速 of the standard speed (in the present embodiment, about 58.435 mm / s).
s), the process speed of the OHP sheet is reduced to 1 /
Fourth speed (about 29.217 mm / s in the present embodiment).

Next, the image formation start timing signal will be described.

This timing signal determines from which position on the print paper an image is to be formed. In the case of a color copying machine, the occurrence of color misregistration can be suppressed by adjusting the image formation start timing signal for each color.
The image formation start timing signal is supplied to the registration rollers 336 and 33 for turning on a registration roller clutch (not shown).
7 to feed the recording medium (CPU 29
Timing when STARTN (signal) is generated from 1)
From a predetermined clock (C generated from an oscillator (not shown))
LKA (signal)). In the related art, the CLKA is constant regardless of the process speed. That is, if the image formation start timing signal is generated by counting the CLKA from FF'h (hexadecimal notation) when the process speed is the standard speed, 1FE'h (= 2) at the process speed of 1/2 speed × FF '
h), when the process speed is 1/4 speed, 3FC'h (=
4.times.FF'h) The CLKA of the emission had to be counted.

On the other hand, in the present invention, the frequency of CLKA is divided in accordance with the process speed. That is, when the process speed is 1/2 speed, the frequency is divided by 2 and the process speed is 1
In the / 4 speed, the frequency is divided by four. By doing so, in the example described above, when the process speed is the standard speed, FF'h
If the image formation start timing signal is generated by counting the number of generated CLKAs, the process speed becomes 1/2 speed, 1 /
Even at the fourth speed, CLKA of FF'h is counted and an image formation start timing signal is generated.

Referring to FIGS. 4 and 5, the configuration of the image formation start timing signal generator corresponding to a plurality of process speeds, which is a feature of the present invention, will be described.

FIG. 4 is a block diagram for explaining the construction of an image formation start timing signal generating section corresponding to a plurality of process speeds of the digital color copying machine shown in FIG. 1. The same components as those in FIG. The code is attached.

In the figure, PCLK is a basic clock,
One cycle is 44.2 ns, and is generated by an oscillator (not shown). Reference numeral 401 denotes an 11-bit counter. Of the outputs of bits 0 to 10 of the 11-bit counter 401, bits 8 (CLKA), 9 (CLKA / 2), 10
(CLKA / 4) is output, and PCLK is divided by one, two, and four.

Reference numeral 402 denotes a process speed setting register, which is set to "00" (standard speed), "0" by the CPU 291.
1 "(1/2 speed) and" 10 "(1/4 speed) are set. Reference numeral 403 denotes a selector, and an 11-bit counter 401
Output signals CLKA, CLKA / 2, CLKA / 4
When the set value of the process speed setting register 402 is “00” (standard speed), CLKA is set to “0”.
1 "(1/2 speed), CLKA / 2, CLKA / 4
Is output to the 18-bit counter 404 when CLKA / 4 is the clock CLKS when the speed is "10" (1/4 speed).

STARTN is a registration roller clutch O
The N signal indicates the timing at which the recording medium is fed by the registration rollers 336 and 337, and is generated by the CPU 291. Reference numeral 411 denotes an 11-bit counter. When STARTN input to the K terminal becomes “L”, a count permission signal KYOKAN for enabling CLK count permission to the 18-bit counter 404 is enabled via the inverter 412 and output from the comparator 405. When COMP1 inputted to the J terminal becomes “H”, the count enable signal KOKAN to the 18-bit counter 404 is disabled.

When the count permission signal KYOKAN input from the JK flip-flop 411 via the inverter 412 is enabled, the 18-bit counter 404 is enabled.
The counting of the clock (CLKS) input from the selector 403 is started and output to the comparator 405. Also,
The 18-bit counter 404 is a JK flip-flop 4
When the count permission signal KYOKAN input from the inverter 11 through the inverter 412 is disabled, the counting of the clock (CLKS) ends. An image formation start register 406 sets the number of clocks (different for each color) until image formation starts.

The comparator 405 compares the count value input from the 18-bit counter 404 with the value set in the image formation start register 406, and compares the value input from the 18-bit counter 404 with the image formation start register. When the count value set in 406 is reached, COMP1 for one clock of PCLK is set to “H” and output to the K terminal of JK flip-flop 410 and the J terminal of JK flip-flop 411.

The JK flip-flop 410 outputs the sub-scanning enable signal ENBN as "L" when COM1 input from the comparator 405 to the K terminal becomes "H". Note that the sub-scanning enable signal ENBN is negative logic.

HSYNC is a main scanning synchronization signal.
It is generated at the main scanning timing from 91. 408 is 14
When the sub-scanning enable signal ENBN output from the JK flip-flop 410 becomes “L” in the bit counter, HSYNC is counted (that is, the number of main scanning lines is counted), and the count value, that is, the main scanning count number is compared with a comparator. 409. Reference numeral 407 denotes an image forming section register in which the number of main scans from the start of image formation to the end of image formation is set.

The comparator 409 compares the count value (the number of main scans) input from the 14-bit counter 408 with the value set in the image forming section register 407, and counts the count input from the 14-bit counter 408. When the value reaches the value set in the image forming section register 407, one clock of PCLK COMP2
Is set to “H” and output to the J terminal of the JK flip-flop 410. This is a counter for determining how many lines of the main scanning output the sub-scanning enable signal ENBN.

The JK flip-flop 410 sets the COMP1 input from the comparator 405 to the K terminal to “H”.
Then, the sub-scanning enable signal ENBN is output as “L”, the sub-scanning enable signal ENBN is enabled (the sub-scanning enable signal ENBN is negative logic), and the COM input from the comparator 409 to the J terminal is output.
When P2 becomes “H”, the sub-scanning enable signal ENBN is set to “H”, and the sub-scanning enable signal ENBN is disabled.

The operation of each section will be described below.

As shown in FIG.
Reference numeral 01 denotes a basic clock, which divides PCLK having a period of 44.2 ns, and outputs bits 8 (CLKA), 9 (CLKA / 2), 10
(CLKA / 4) is input to the selector 403. If the value of the process speed setting register is "00" (standard speed),
When "01" (1/2 speed) and "10" (1/4 speed)
The selector 403 outputs CLKA and CLKA /
2, CLKA / 4.

The JK flip-flop 411 has a STAR
When the TN (registration roller clutch ON signal) becomes “L”, the 18-bit counter 404 is permitted to count. Thus, the 18-bit counter 404 counts the clock output from the selector 403, and when the value becomes equal to the value of the image formation start register, the comparator 405 outputs "H" for one PCLK.

The output of the comparator 405 is input to the JK flip-flop 411. When the output of the comparator 405 becomes "H", the count enable signal of the 18-bit counter 404 is disabled.

The output of the comparator 405 is JK
The signal is also input to the flip-flop 410, and when the output of the comparator 405 becomes “H”, the output of the JK flip-flop 410 becomes “L”. The output of the JK flip-flop 410 is used as a sub-scanning enable signal. The sub-scanning enable signal has negative logic.

When the sub-scanning enable signal becomes "L",
The 14-bit counter 408 starts counting the main scanning synchronization signal. This is a counter for determining how many lines of the sub-scanning enable are output. 14-bit counter 4
When the count value of 08 becomes equal to that of the image forming section register 407, the comparator 409 outputs "H" for one PCLK clock.

The comparator 409 is connected to the J terminal of the JK flip-flop 410.
9 becomes "H", the JK flip-flop 41
0 outputs "H" and the sub-scanning enable signal is disabled. This timing is shown in FIG. 5 for each process speed.

FIG. 5 is a timing chart showing image formation start signal timings corresponding to a plurality of process speeds of the digital color copying machine shown in FIG. 1. In particular, here, the yellow (Y) station closest to the registration roller is shown. Will be described.

As shown in the figure, by changing the period of the CLKS output from the selector 403 in accordance with the process speed, the CLKS output from the 18-bit counter 404 is changed.
COUNT18 which is the counting result of “6CB4
(In hexadecimal notation) ", the output COMP1 from the comparator 405 becomes" H ", and the sub-scanning enable signal ENBN generated by the JK flip-flop 410 can be set to" L "(the image formation start signal is generated). can do).

COUNT1 which is the counting result of the main scanning synchronization signal HSYNC by the 14-bit counter 408
4 is “133F (hexadecimal notation)”, the output COMP2 from the comparator 409 becomes “H”, and J
The sub-scanning enable signal ENBN generated by the K flip-flop 410 is set to “H” (image formation can be ended).

Here, the cycle of CLKA output from 11-bit counter 401 is PCLK (the cycle is about 44.2 ns in this embodiment) divided by 512, and thus the cycle is 22.6 μs. . This CLKA is counted for the number of “6CB4” shots because of the distance of half the circumference of the Y drum + drum from the registration roller (in this embodiment, about 7
3.3939 mm) at the standard process speed (about 1
18.6694 mm / s), the time “22.6
μs × 6CB4 = 0.628 s ”.

Similarly, an 11-bit counter 401
The cycle of CLKA / 2 output from PCLK is 10
Since CLKA / 2 is divided by 24, this CLKA / 2 is
When counting the number of shots of "CB4", the Y roller +
It is the time obtained by dividing the distance for half the circumference of the drum by the process speed of 1/2 speed (about 58.435 mm / s), and further, the CLKA output from the 11-bit counter 401
Since the cycle of / 4 is obtained by dividing PCLK by 2048, when this CLKA is counted for "6CB4", the distance of the half circumference of Y drum + drum from the registration roller is 1/1.
It is the time divided by the fourth process speed (about 29.217 mm / s).

Although the image formation start timing of the yellow (Y) station has been described above, the image formation start timing of each of the other magenta (M), cyan (C), and black (K) stations is substantially the same. The image forming start timing circuit is different from that in the case of magenta (M) in that the STRT (registration roller clutch O) is input to the JK flip-flop.
N signal), the count start signal of the COUNT 18 is changed to a yellow (Y) image formation start timing signal CO.
As in the case of using MP1, each of the 18-bit counters 404 is moving the COUNT 18 after the station at the preceding stage starts to form an image.

The registration roller clutch is turned on (ST
RTN), the 18-bit counter 404 is C
When the output of the COUNT 18 is started (the counting of the CLKS is started), the number of bits of the COUNT 18 of the station far from the registration roller is increased and the circuit scale is increased.

Here, as described in the section of the problem to be solved by the invention, the values stored in the conventional image forming apparatus, that is, the image forming start register and the image forming section register with the change of the process speed are changed. In the rewriting configuration, the counter for counting clocks is increased by 2 bits (the process speed is increased to the standard speed, 1/2 speed, 1 speed) as compared with an image forming apparatus having a constant process speed.
(2 bits if it can be changed to / 4 speed).

Further, in the image forming apparatus of the present invention, that is, in a configuration in which a clock having a cycle corresponding to the process speed is compared with a fixed value to determine the image forming timing, the image forming apparatus has a constant process speed. A counter for generating a clock having a cycle corresponding to the process speed (corresponding to the 11-bit counter 401 in this embodiment) is increased by 2 bits (the process speed is changed to the standard speed, 1/2 speed, and 1/4 speed). When possible, the image forming apparatus which supports a plurality of process speeds in both the conventional configuration and the configuration of the present invention has a counter which is larger than an image forming apparatus having a constant process speed. It is necessary to increase by 2 bits.

However, in the above-described conventional configuration, a register (image formation start register) for comparing the counter value needs to be further increased by two bits as compared with an apparatus having a constant process speed (process speed is set to standard speed, 1/2). Although there is a case where the speed can be changed to a 1/4 speed, in the configuration of the present invention, even if the process speed is changed, the counter value is constant. It is not necessary to increase the number of bits of the image forming start register 406), and an image forming apparatus having a plurality of process speeds can be realized while minimizing the increase in circuit scale as compared with the conventional image forming apparatus. Can be.

Further, in the digital color copying machine shown in FIG. 1, the image forming start position is set to one of 600 dpi1 line.
Although the adjustment can be made in 1/6 units, when a single clock is counted as in the configuration of the prior art, the adjustment value set in the register is 1, 1 at the standard speed and 2, 1 at the 1/2 speed. /
The program had to be changed in four units at four speeds, making the program more obscured, and the burden of software development increased.
On the other hand, in the configuration of the present invention, the image formation start position can always be determined at 1/16 of 600 dpi1 line for the adjustment value 1 regardless of the process speed, and the program is simplified.

Therefore, even in an image forming apparatus having a plurality of process speeds, it is possible to avoid complication of the control program.

With the above circuit configuration,
Even if the image forming apparatus has a plurality of process speeds, the circuit scale does not need to be increased, and the control program can be prevented from becoming crowded. Although three types of process speeds have been described here, it is needless to say that the present invention is not limited to the three types of process speeds.

The 11-bit counter 401 and the process speed setting register 40 as means for generating a clock having a cycle corresponding to the process speed shown in FIG.
2. Even if the selector 403 is provided in each image forming start timing signal generating unit for each color component, only one set is provided for the entire image forming apparatus, and the selector 403 is used jointly by the image forming start timing signal generating units for each color component. May be configured.

[Second Embodiment] In the first embodiment,
The case where the present invention is applied to the digital color LED copying machine shown in FIG. 1 has been described.
The present invention is not limited to a copying machine, and may be applied to all image forming apparatuses (including monochrome) using a sub-scanning enable signal regardless of other electrophotographic systems, ink jet, sublimation systems, and other systems.

[Third Embodiment] In the first embodiment,
Although the case where the image formation start timing signal generation unit is configured by hardware has been described, a program corresponding to the function of the image formation start timing signal generation unit is stored in ROM
292 or a recording medium (not shown)
May be configured to be executed.

Hereinafter, referring to the flowchart of FIG.
The operation of generating an image formation start timing signal according to the present invention will be described.

FIG. 6 is a flowchart showing an example of the procedure for generating an image formation start timing signal according to the present invention. In particular, the procedure for generating an image formation start timing signal for the yellow (Y) station closest to the registration roller will be described. . (1) to (8) indicate each step.

First, values according to the set process speed, ie, "00" (standard speed), "01" (1/2)
Speed) and "10" (1/4 speed) are set in the process speed setting register 402 (1), and a basic clock CLKS having a frequency corresponding to the process speed is generated.

Next, when STARTN (registration roller clutch ON signal) becomes "L" (2), the selector 40
Then, counting of the basic clock CLKS output from No. 3 is started (3). The basic clock CLKS is counted until it reaches a predetermined value, for example, “6CB4”. If it is determined that the count value of the basic clock CLKS has become “6CB4” (4),
The sub-scanning enable signal ENBN is output as "L" (5), and image formation is started. That is, the main scanning synchronization signal H
The main scanning is performed every time SYNC occurs.

Next, the number of main scanning lines (main scanning synchronization signal H
SYNC) is started (6), and a predetermined value, for example, “1”
The number of main scanning lines is counted until the number reaches 33F. If it is determined that the count value of the basic clock CLKS has become "133F" (7), the sub-scanning enable signal ENBN is output as "H" (8). Then, the image formation ends.

As described above, by generating a clock corresponding to the process speed, the circuit scale does not need to be increased even in an image forming apparatus having a plurality of process speeds. In addition, it is possible to avoid obfuscation of the control program.

As described above, the storage medium storing the program codes of the software for realizing the functions of the above-described embodiments is supplied to the system or the apparatus, and the computer (or CPU or MP) of the system or the apparatus is supplied.
It goes without saying that the object of the present invention is also achieved when U) reads out and executes the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the novel function of the present invention, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, C
DR, magnetic tape, nonvolatile memory card, RO
M, EEPROM and the like can be used.

The functions of the above-described embodiments are implemented when the computer executes the readout program codes, and the OS (Operating System) running on the computer is executed based on the instructions of the program codes. ) And the like perform part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instruction of the program code, The CPU provided in the function expansion board or function expansion unit performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

Further, the present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus. In this case, by reading a storage medium storing a program represented by software for achieving the present invention into the system or the apparatus, the system or the apparatus can enjoy the effects of the present invention. .

Further, by downloading and reading out a program represented by software for achieving the present invention from a database on a network by a communication program, the system or apparatus can be
It is possible to enjoy the effects of the present invention.

[0112]

As described above, according to the first and second aspects of the present invention, an image forming apparatus capable of forming an image on a recording medium conveyed at a speed corresponding to a set process speed. , A generating means generates a clock having a cycle corresponding to the set process speed, a first counting means counts a clock generated by the generating means, and based on a count value of the first counting means. The first determining means determines the image forming start timing (based on a result of comparison between the count value of the first counting means and a predetermined value), so that a simple circuit configuration can cope with a plurality of process speeds. The start timing of image formation can be accurately generated.

According to the third aspect, the second counting means for counting the number of main scanning lines, and the second counting means for determining the image forming section in the sub-scanning direction based on the count value of the second counting means. Since the determination means is provided, an image corresponding to a plurality of process speeds can be formed with an accurate sub-scanning width with a simple circuit configuration.

According to the fourth aspect, the recording medium conveyed at a speed corresponding to the set process speed is
In an image forming apparatus capable of forming a multicolor image by superimposing color component images formed by image forming units for each color component arranged side by side, a clock generating unit generates a clock having a cycle according to the set process speed, The clock generated by the generating unit is counted by the counting unit for each color component, and the determining unit for each color component determines the image forming start timing for each color component based on the count value of the counting unit for each color component. Therefore, the start timing of forming each color component image in the color image forming operation corresponding to a plurality of process speeds can be accurately generated with a simple circuit configuration.

According to the fifth aspect of the present invention, there is provided a method for controlling an image forming apparatus capable of forming an image on a recording medium conveyed at a speed corresponding to a set process speed. A periodic clock is generated, the generated clock is counted, and the image forming start timing is determined based on the counted value. Therefore, the start of image forming corresponding to a plurality of process speeds can be started with a simple circuit configuration. Timing can be generated accurately.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a binary recording digital color copying machine using an LED array (600 dpi) as an exposure system to which an image forming apparatus according to a first embodiment of the present invention can be applied.

FIG. 2 is a block diagram illustrating a configuration of an image processing unit illustrated in FIG. 1;

FIG. 3 is a block diagram illustrating a configuration of an image processing unit illustrated in FIG. 1;

FIG. 4 is a block diagram illustrating a configuration of an image formation start timing signal generation unit corresponding to a plurality of process speeds in the digital color copying machine shown in FIG.

FIG. 5 is a timing chart showing an image formation start signal timing corresponding to a plurality of process speeds of the digital color copying machine shown in FIG.

FIG. 6 is a flowchart illustrating an example of an image formation start timing signal generation procedure according to the present invention.

[Explanation of symbols]

 291 CPU 292 ROM 293 RAM 401 11-bit counter 402 Process speed setting register 403 Selector 404 18-bit counter 405 Comparator 406 Image formation start register 410 JK flip-flop

Claims (5)

[Claims] 1. An image forming apparatus capable of forming an image on a recording medium conveyed at a speed according to a set process speed, comprising: a generation unit for generating a clock having a cycle according to the set process speed; A first counting means for counting clocks generated by said generating means;
An image forming apparatus comprising: a counting unit; and a first determining unit that determines an image forming start timing based on a count value of the first counting unit. 2. The image forming apparatus according to claim 1, wherein the first determining unit determines an image forming start timing based on a comparison result between a count value of the first counting unit and a predetermined value. Image forming apparatus. A second counting unit that counts the number of main scanning lines; and a second determining unit that determines an image forming section in the sub-scanning direction based on a count value of the second counting unit. The image forming apparatus according to claim 1, wherein: 4. A multi-color image can be formed by superimposing a color component image formed by an image forming unit for each color component arranged side by side on a recording medium conveyed at a speed corresponding to a set process speed. In the image forming apparatus, a generating unit that generates a clock having a cycle according to the set process speed, a counting unit for each color component that counts a clock generated by the generating unit, and a counting unit for each color component An image forming apparatus for determining an image formation start timing for each color component based on the count value of the color components. 5. A method for controlling an image forming apparatus capable of forming an image on a recording medium conveyed at a speed according to a set process speed, wherein a clock having a cycle according to the set process speed is generated. A method for controlling an image forming apparatus, comprising: a generating step; a counting step of counting the generated clock; and a determining step of determining an image forming start timing based on the counted value.