JP2001026142A - Color image forming apparatus and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to certainly discriminate a TOP signal even if noise is mixed and to enable stable image forming operation. SOLUTION: A color image forming apparatus for forming a color image on the basis of color image data has an image forming part for successively forming images of a plurality of color components on the basis of image data at every provided color components to form a color image and this image forming part issues a TOP signal showing timing for providing the image data at every color components to a controller. Herein, the TOP signal is different in its pulse width corresponding to the color components of the required image data and the controller judges rightfulness of the TOP signal on the basis of the pulse width. The controller provides the image data of the corresponding color component when judges the TOP signal to be right.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a color image forming apparatus and a control method thereof.

[0002]

2. Description of the Related Art Conventionally, there has been known a color image forming apparatus which forms an image by sequentially superimposing images of respective color components on an intermediate transfer member. FIG. 11 is a block diagram showing a schematic configuration of this type of color image forming apparatus. According to the configuration of FIG. 11, multicolor printing is performed by an electrophotographic process. At this time, the latent images formed by the light beams polarized from the polygon mirror 1 on the photoreceptor 2 were sequentially developed by developers of different colors, and the developed images were superimposed on the intermediate transfer member 3 to obtain a latent image. The image is transferred onto a recording medium to obtain a color image.

In the above configuration, the image forming section 4 transmits a print start signal 12 (hereinafter referred to as a TOP signal) to the image processing section 11 (controller) via a TOP signal line 12 as a synchronization signal in the sub-scanning direction. The image processing unit 11 counts signals in the main scanning direction from the leading edge of the TOP signal, and outputs image information to the image forming unit 4 when the count reaches the printing area.

In the image forming section 4, yellow 5, magenta 6, cyan 7, and black 8 based on image information transmitted from the controller 11 via the DATA line 10.
The color developer is sequentially superimposed on the intermediate transfer member 3 to obtain a full-color image.

[0005]

In the above conventional example, TOP is used.
When the signal is transmitted normally, the intended image can naturally be output to the print medium. However, depending on the usage environment, noise may be superimposed on the TOP signal line 12 during image formation due to static electricity or external noise by the user. At this time, if the controller recognizes this noise as a TOP signal, the data output timing will be shifted, causing abnormalities such as an incomplete image or missing colors to be printed. Become.

The present invention has been made in view of the above problems, and has as its object to make it possible to identify a TOP signal reliably and to perform a stable image forming operation.

[0007]

To achieve the above object, a color image forming apparatus according to the present invention has, for example, the following arrangement. That is, a color image forming apparatus that forms a color image based on color image data, and sequentially forms images of a plurality of color components based on provided image information for each color component to form a color image Means for issuing a request signal indicating timing for providing image information to the forming means for each color component; determining means for determining the validity of the request signal issued by the request means; And providing means for providing image information corresponding to the color component to the forming means when the request signal is determined to be valid.

A method for controlling a color image forming apparatus according to the present invention for achieving the above object includes, for example, the following steps. That is, a method of controlling a color image forming apparatus that forms a color image based on color image data, wherein an image of a plurality of color components is sequentially generated based on the provided image information for each color component to form a color image A forming step of forming, and an issuing step of issuing a request signal indicating timing for providing image information to the forming step for each color component,
A determining step of determining the validity of the request signal issued from the requesting step, and a providing step of providing image information corresponding to a color component to the forming step when the request signal is determined to be valid. Is provided.

[0009]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a block diagram showing a schematic configuration of a color image forming apparatus according to a first embodiment. In FIG. 1, reference numeral 1 denotes a scanner unit, which includes a semiconductor laser (not shown) and a polygon mirror.
Reference numeral 13 denotes a waste toner BOX for storing the developer and cleaning the photoconductor, reference numeral 14 denotes a charging roller for uniforming the charge on the photoconductor surface, and reference numeral 2 denotes a photoconductor. The photoconductor 2, the waste toner BOX 13, and the charging roller 14 are collectively configured as a developing cartridge. In particular, 5 is a yellow developing cartridge YC, 6 is a magenta developing cartridge MC, 7 is a cyan developing cartridge CC, and 8 is black. Of the developing cartridge BKC.

3 is an intermediate transfer member, 9 is a CPU, 15
Is a transfer roller for transferring the developed image to the print medium, and 16 is a fixing device for fixing the toner image transferred on the print medium to the print medium. The configuration of the image forming unit 4 has been described above.

Reference numeral 10 denotes a DATA line, which is a transmission line for transmitting a color image signal or the like. Reference numeral 11 denotes an image processing unit (controller) for processing and sending image information to the image forming unit 4. A TOP signal line 12 transmits a TOP signal as a synchronization signal for starting printing. A PRNT line 24 transmits a PRNT signal for instructing an image forming operation.

A host computer 19 provides image data to be recorded to the image forming apparatus via a printer interface 18.

Next, the operation of the above configuration will be described. The CPU 9 in the image forming unit 4 generates a TOP signal at a transmission timing for each color in the image forming operation. CPU 9
Is transmitted to the controller 11 via the TOP signal line 12, the controller 11 outputs image data to the image forming unit 4. In accordance with the data, an electrostatic latent image is formed on the photoconductor 2 by the laser light of the scanner unit 1, and the latent image on the photosensitive drum is first developed by the Y developing device 5 to form a yellow toner image. Then, this toner image is transferred to the intermediate transfer body 3. Similarly, M (magenta), C (cyan), Bk
(Black) and the above process is repeated in order, and the intermediate transfer body 3
A full-color toner image is formed thereon. Thereafter, the image is re-transferred to the print medium, fixed on the print medium by the fixing device 16, and discharged.

The image forming apparatuses are classified into an image forming section 4 for actually forming an image and an image processing section 11 (controller) for processing image data sent from a host 19 such as a network computer. When image data is sent from the host 19 via the printer interface 18, the controller 11 receives the image data,
The print start signal PRNT signal is transmitted to the image forming section 4. The image forming operation is started by the PRNT signal. After that, the CPU 9 of the image forming unit 4
In synchronization with the sub-scanning direction.
The signal is sent to the controller 11 via the TOP signal line 12.
Send to The controller 11 transmits image data in synchronization with these signals.

FIG. 2 shows the controller 11 and the image forming section 4.
FIG. 4 is a diagram showing general timings of signals between and. FIG. 3 is a diagram showing signal timings between the controller 11 and the image forming unit 4 according to the present embodiment.

When the PRNT signal is sent to the image forming apparatus 4, first, the CPU 9 sends a TOP corresponding to Y (yellow).
A signal (Ytop) is transmitted to the controller 11. The controller 11 enters the video signal transfer permission state (/ VDOEN) in synchronization with the rise of Ytop,
The image data of Y (yellow) is transmitted to the image forming unit 4. Next, the CPU 9 returns a TOP corresponding to M (magenta).
When the signal (Mtop) is transmitted to the controller 11,
M (magenta) image data is transmitted from the controller 11 to the image forming apparatus. Similarly, the image forming unit 4
, A TOP signal (Ctop) corresponding to C (cyan),
TOP signal (BKtop) corresponding to BK (black)
Is transmitted from the controller 11, the image data corresponding to C and the image data corresponding to BK are transmitted to the image forming unit 4. Thus, a full-color image is formed in the image forming section 4.

Now, as shown in FIG. 2, a general T
The same signal is used for the OP signal for each color. On the other hand, in the first embodiment, by changing the pulse width of the TOP signal for each color as shown in FIG.
It is possible to identify which color the TOP signal corresponds to.

FIG. 4 is a flowchart showing the operation of the controller according to the first embodiment. Controller 1
1 receives the image data from the host computer 19 and transmits a PRNT signal to the image forming unit 4 (step S11). Then, in step S12, the process waits for a TOP signal to be received from the image forming unit 4. Image forming unit 4
When a TOP signal is received, the process proceeds to step S13.
The pulse width of the TOP signal is detected, and in step S14, it is determined whether the pulse width properly corresponds to the color.

If it is determined that the pulse width is not valid,
Proceeding from step S14 to step S15, the signal received via the TOP signal line 12 is determined to be noise, and the process returns to step S12 to wait for the next TOP signal.

On the other hand, if it is determined that the pulse width is valid, the process proceeds from step S14 to step S16, and the data of the corresponding color is transmitted in synchronization with the rise of the TOP signal.

For example, the CPU 9 of the image forming unit 4
When the op is sent to the controller 11, the controller 1
In step 1, the pulse width is detected (step S13).
It recognizes what color the transmitted top signal is (step S14), and then transmits image data corresponding to the color (step S16). Here, even if sudden noise is mixed into the transmission line of the top signal, the controller 11 first recognizes the noise as top and identifies what color it is (step S13). However, by making the top pulse sufficiently large with respect to the noise, the controller 11 can separate the top signal from the noise (step S14), and the controller always determines what color the image is being formed. It becomes possible to recognize.

In step S14, the order of colors to be processed can be taken into account. For example, since the TOP signal received after processing yellow corresponds to magenta, its legitimacy is determined based on whether the pulse width of the received TOP signal has a pulse width specified in Mtop. You may make it.

As described above, according to the first embodiment,
Since the pulse width of the TOP signal is changed according to each color,
It is possible to reliably determine whether the signal input as the TOP signal is legitimate or noise, and to perform a stable image forming operation.

<Second Embodiment> In the first embodiment,
It has been proposed to distinguish between signal and noise by transforming the TOP signal. On the other hand, in the second embodiment, signal and noise are identified based on the generation interval of the TOP signal.

FIG. 5 is a block diagram showing a schematic configuration of the image forming apparatus according to the second embodiment. In FIG. 5, the first
The same components as those of the embodiment (FIG. 1) are denoted by the same reference numerals, and some of them are not shown. In FIG. 5, reference numeral 20 denotes a motor for driving the intermediate transfer member (3). A pulse counter 21 counts driving pulses of the motor 20. A comparator 22 compares a count value of the pulse counter 21 at the time when the TOP signal is input with a predetermined value. 23 is a TOP right / wrong judgment unit,
It is determined whether or not the TOP signal is valid based on the comparison result of the comparator 22.

Next, the operation of the image forming apparatus according to the second embodiment will be described. FIG. 6 is a flowchart showing the operation of the controller according to the second embodiment. When a print command is sent from a host 19 such as a network computer, the controller 11 sends a PRNT signal to the image forming unit 4.
(Step S21). The image forming unit 4 receives this and sends the TOP signal 1 from the CPU 9 to the controller 11 side.
Send 2 In the controller 11 that has received the TOP signal, the comparator 22 acquires the count value of the pulse counter 21 (Steps S22 and S23) and compares the count value with a predetermined value (Step S24). If the acquired count value is the specified value, the process proceeds to step S25, where TOP
The image data is transmitted to the image forming unit 4 in synchronization with the rise of the signal. On the other hand, if the acquired count value is not the default value, the process proceeds to step S26, assuming that the TOP signal is invalid, returns to step S22 without doing anything, and waits for the next TOP signal.

Here, the operations in steps S23 and S24 will be described in more detail. FIG. 7 is a diagram illustrating timing of signals between the controller 11 and the image forming unit 4 according to the present embodiment.

The pulse counter 21 is driven by a driving pulse of the motor 20 for driving the intermediate transfer member 3 of the image forming section 4 to change the first color TOP signal from Ytop to Mtop.
Count the interval up to. Ytop, Mtop, Mt
The interval between op and Ctop is equal and constant, and Ctop and B
The interval of Ktop is also constant. Therefore Ytop-Mt
The constant interval between op and Mtop-Ctop is m, Ctop-
Assuming that the predetermined interval of BKtop is n, the drive pulse starts counting from the rising edge of Ytop and continues counting until the next rising edge of Mtop is detected.

The comparator 22 compares the count number of the pulse counter 21 with a prescribed value. If they are equal, the controller 11 converts the top signal transmitted at that time into a normal M signal.
The top color is recognized, and the process proceeds to the next color image forming process (step S24). After that, Mtop-Ctop
The interval and the Ctop-BKtop interval are counted, and it is determined whether or not each top signal is normal.

As described above, according to the second embodiment,
Even if noise enters the transmission line of the TOP signal,
The count number at that time is compared with the count m at the time of normal operation, and if they are not equal, the controller 11 determines that the signal is noise and ignores it, and advances the pulse counter 21 until a normal TOP signal is transmitted from there. . As a result, even when noise is mixed, it is possible to distinguish between the noise and the TOP signal.

<Third Embodiment> Next, a third embodiment will be described. In the first embodiment, the color information is added according to the pulse width of the TOP signal.
A signal line separate from the P signal is provided to add color information.

FIG. 8 is a block diagram showing a schematic configuration of an image forming apparatus according to the third embodiment. In FIG. 8, the same components as those of the first embodiment (FIG. 1) are denoted by the same reference numerals, and some of them are not shown. According to FIG. 8, the ID SIGNAL line 23 (2 bits in this example) is used to notify the color information to the controller.
Is different from the configuration of the first embodiment.

Next, the operation of the image forming apparatus according to the third embodiment will be described. FIG. 9 is a flowchart showing the operation of the controller according to the third embodiment.

Host 1 such as a network computer
When a print command is sent from the controller 9, the controller 11
An RNT signal is transmitted to the image forming unit 4 (Step S3)
1). In response to this, the image forming unit 4 sends a TOP signal from the CPU 9 to the controller 11 on the TOP signal line 12. Then, at this time, the image forming unit 4
The color information indicating the color corresponding to the signal is stored in IDSIGNAL2
3 output.

When receiving the TOP signal, the controller 11 acquires the color information transmitted on the IDSIGNAL 23, and checks whether the TOP signal is transmitted together with valid color information (steps S32 and S33).
If it is determined that the TOP signal is sent together with the valid color information, the process proceeds from step S34 to step S3.
Proceeding to 5, the controller 11 transmits the image data to the image forming unit 4 in synchronization with the rise of the TOP signal. On the other hand, if the legitimate color information is not attached to the TOP signal, the process proceeds from step S34 to step S36, assuming that the TOP signal is invalid, and returns to step S32 without doing anything. Wait for.

The color information and the processing related thereto will be further described. The controller 9 is provided by the CPU 9 of the image forming unit 4.
When a TOP signal is transmitted to a plurality of bits (IDSI
GNAL 23) to add color information. As in the present embodiment, when printing is performed in four colors of CMYK, 2 bits are sufficient, and when printing is performed in more colors, 3 bits are used.
t and 4 bits are added.

FIG. 10 shows a TOP signal 12, a PRINT signal, and additional bits for color information (IDSIGNAL1,
2) is a timing chart of image data. When transmitting Ytop, both ID1 and ID2 are LO signals as additional signals.
W is ID1 as an additional signal when transmitting Mtop.
Is set to HIGH, ID2 is set to LOW, and transmitted. Similarly, C
In top, ID1 is LOW, ID2 is HIGH, BKt
In op, both ID1 and ID2 are set to HIGH and transmitted to the controller 11.

As described above, according to the third embodiment,
Since the controller can recognize the color information being formed in the image forming unit, even if the count of the top signal is missed due to noise in the transmission line of the top signal, the controller recognizes the mistake and recognizes the image currently being printed. Can be temporarily reset and reprinted.

According to each of the embodiments described above, even when noise is superimposed on the transmission line of the TOP signal, which is a synchronization signal in the sub-scanning direction, it is possible to separate the noise from the TOP signal. Further, since it is possible to recognize the color information being formed, it is possible to perform a printing operation normally without causing a malfunction such as a color order shift or a missing color, or an incomplete printing.

Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine, a facsimile, etc.) comprising Device).

[0042]

As described above, according to the present invention,
The TOP signal can be reliably identified, and a stable image forming operation can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a color image forming apparatus according to a first embodiment.

FIG. 2 is a diagram showing general timings of signals between a controller 11 and an image forming unit 4.

FIG. 3 is a diagram showing signal timings between a controller 11 and an image forming unit 4 according to the embodiment.

FIG. 4 is a flowchart illustrating an operation of the controller according to the first embodiment.

FIG. 5 is a block diagram illustrating a schematic configuration of an image forming apparatus according to a second embodiment.

FIG. 6 is a flowchart illustrating an operation of a controller according to the second embodiment.

FIG. 7 is a diagram illustrating timing of signals between the controller 11 and the image forming unit 4 according to the present embodiment.

FIG. 8 is a block diagram illustrating a schematic configuration of an image forming apparatus according to a third embodiment.

FIG. 9 is a flowchart illustrating an operation of a controller according to the third embodiment.

FIG. 10 is a timing chart of a TOP signal 12, a PRINT signal, additional bits for color information (IDSIGNAL1, 2), and image data.

FIG. 11 is a block diagram illustrating a schematic configuration of a color image forming apparatus of this type.

[Description of Signs] 1 scanner unit 2 photoreceptor 3 intermediate transfer member 4 image forming unit 5 developing cartridge (yellow) 6 developing cartridge (magenta) 7 developing cartridge (cyan) 8 developing cartridge (black) 9 CPU 10 DATA line 11 controller 12 TOP signal line 13 Developer storage / waste toner BOX 14 Charging roller 15 Transfer roller 16 Fixing device 17 Paper discharge port 18 Interface 19 Host computer

Claims (10)

[Claims] 1. A color image forming apparatus for forming a color image based on color image data, the method comprising: sequentially generating images of a plurality of color components based on provided image information for each color component to form a color image Forming means for forming; issuing means for issuing a request signal indicating timing for providing image information to the forming means for each color component; determining means for judging the validity of the request signal issued by the request means And a providing unit that provides the forming unit with image information corresponding to a color component when the request signal is determined to be valid. 2. The issuing unit changes the pulse width of the request signal according to each color component, and the determination unit determines the validity of the request signal by examining the pulse width of the request signal. The color image forming apparatus according to claim 1, wherein: 3. The color image forming apparatus according to claim 1, wherein the determination unit determines the validity of the request signal by measuring a time interval between the issued request signals. 4. The method according to claim 1, wherein the forming unit sequentially generates an image for each color component on the intermediate transfer body, and the measuring unit measures the time interval between the request signals.
4. The color image forming apparatus according to claim 3, wherein the driving is performed using a driving signal for driving the intermediate transfer member. 5. The issuing unit issues an identification signal indicating a color component to be provided together with the request signal, and the determining unit determines whether the request signal is valid based on the identification signal attached to the request signal. The color image forming apparatus according to claim 1, wherein the property is determined. 6. A method for controlling a color image forming apparatus for forming a color image based on color image data, the method comprising sequentially generating images of a plurality of color components based on provided image information for each color component. A forming step of forming a color image, an issuing step of issuing a request signal indicating timing for providing image information to the forming step for each color component, and judging the validity of the request signal issued from the requesting step And a providing step of providing image information corresponding to a color component to the forming step when the request signal is determined to be valid. . 7. The issuing step changes a pulse width of the request signal according to each color component, and the determination step determines validity of the request signal by examining a pulse width of the request signal. The method for controlling a color image forming apparatus according to claim 6, wherein: 8. The control of the color image forming apparatus according to claim 6, wherein the judging step judges the validity of the request signal by measuring a time interval between the issued request signals. Method. 9. The method according to claim 1, wherein the forming step sequentially generates an image for each color component on the intermediate transfer body, and measuring the time interval between the request signals in the determining step includes:
9. The control method according to claim 8, wherein the control is performed using a drive signal for driving the intermediate transfer member. 10. The issuing step issues an identification signal indicating a color component to be provided together with the request signal, and the determining step determines whether the request signal is valid based on the identification signal attached to the request signal. 7. The control method for a color image forming apparatus according to claim 6, wherein the determining is performed.