JPH07209945A - Color image processor - Google Patents

Abstract

PURPOSE:To prevent the generation of color slippage on the rear end part of paper by determing a rear end erasing period for picture data based upon a stored count value about a 2nd color and after. CONSTITUTION:A picture data signal F is inputted with a delay of prescribed delay time D3 from a transfer drum reference signal E similarly to a 1st color development. At the point of time, the trailing point of a picture validating signal D is not determined but the counting operation of a counter 14 started at the time of generating the signal E is continued. During the period of the counting operation, a control device 12 always compares a final count value N stored in its storing means with the value of an output signal I from the counter 14. When the output signal I becomes equal to the final count value N, the control device 12 raises the signal D and executes the rear end erasing processing of the data F to obtain a picture data signal G to be finally written.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image processing apparatus such as a digital copying machine.

[0002]

2. Description of the Related Art In a color image processing apparatus, one color image is usually obtained by developing four color materials (color toners) on a sheet of paper so that they are superposed one by one. There is. In such a device, when the paper is fed from a normal paper tray, the size of the paper is known from the beginning as the device, so the development range on the paper can be made uniform for all color materials. If the paper is fed from the device, the size of the paper that is initially fed, especially the size in the sub-scanning direction, is unknown, and as a result, color misregistration may occur at the trailing edge of the paper. is there.

FIG. 4 shows a block diagram of a conventional color image processing apparatus having a manual feed tray. 1 is a manual feed tray, 2 is paper, 3 is a registration sensor, 4 is a registration roll, 5 is a registration roll detector, 6 is an image reading device, and 7 is RO.
S and 8 are developing drums, 9 is a rotary toner supply device, and 10
Is a transfer drum, 11 is a reference signal detector, and 12 is a controller.

In the apparatus shown in FIG. 4, when the sheet 2 is supplied from the manual feed tray 1, the sheet 2 passes through the registration sensor 3 and the registration roll 4 and is attached to the transfer drum 10. On the other hand, the color image signal read by the image reading device 6 is input to the control signal 12, and is written on the developing drum 8 from the ROS 7 for each color. Then, a color material is placed on the developing drum 8 from the corresponding toner supply device 9, and the developing material is sequentially developed on the paper 2 on the transfer drum 10. The reference signal detector 11 detects a reference signal generated at a predetermined rotation position of the transfer drum 10 and inputs it to the control device 12 as a signal E. Further, the registration roll detector 5 detects whether or not the sheet 2 is present at the position of the registration roll 4 and outputs a signal B, which is input to the control device 12 together with the detection signal A of the registration sensor 3.

Next, the operation of the apparatus shown in FIG. 4 will be described based on the time chart shown in FIG. When the paper 2 is supplied from the manual feed tray 1 and passes the registration sensor 3, the paper 2
A registration sensor detection signal A which rises when the registration sensor 3 is entered and falls when the registration sensor 3 is exited
Occurs. When the sheet 2 approaches the position of the registration roll 4, the registration roll detector 5 generates a registration roll detection signal B which rises when the sheet 2 enters the registration roll 4 and falls when the sheet 2 exits the registration roll 4. The registration sensor detection signal A and the registration roll detection signal B are input to the control means 12, and the logical product (AND) of the signals A and B is taken inside the control device 12 to obtain the paper detection signal C (= A * B). Is created. That is, the paper detection signal C is a signal that rises in synchronization with the rise of the registration roll detection signal B and falls in synchronization with the fall of the registration sensor detection signal A, and is manually inserted at the positions of the registration sensor 3 and the registration roll 4. The size of the paper 2 in the sub-scanning direction is detected.

Next, an image effective signal D is created by delaying the rising and falling edges of the paper detection signal C by predetermined delay times D1 and D2, respectively. The image valid signal D is a gate signal that determines the time range in which the read image signal F is validated, and varies depending on the size of the supplied paper. The reason why such a signal D is generated is to prevent the color material from being deposited on the developing drum 8 beyond the size of the sheet, and thereby to prevent the toner from being transferred onto the transfer drum 10. There is. From the registration roll position where the paper detection signal C is detected,
Since there is a physical distance to the position of the developing drum 8 / transfer drum 10 to which an image is transferred, the delay time D
It is set as 1 and D2.

On the other hand, as the transfer drum 10 rotates,
The transfer drum reference signal E generated at a predetermined position is detected by the reference signal detector 11 and input to the control device 12.
The control device 12 delays the transfer drum reference signal E by a predetermined delay time D3 and takes in the image data signal F. Then, the image valid signal D is used as a gate signal to erase the rear end of the image data signal F. That is, the trailing edge of the image data signal F is forcibly cut off at the trailing edge of the image valid signal D, and the signal from which the trailing edge is cut off is actually written into the image data signal G (= D
* F) is given to ROS7. After that, the ROS 7 irradiates the developing drum 8 with a laser beam in accordance with the image data signal G, and the color material of the first color is placed on the developing drum 8 from the toner supply device 9 and transferred onto the sheet 2. . The above is the operation until the paper is fed from the manual feed tray 1 and the first color is developed.

Next, the operation of the developing process for the second and subsequent colors will be described. At the time of developing the second color and thereafter, the paper 2 is already placed on the transfer drum 10 and does not pass the positions of the registration sensor 3 and the registration roll 4. Therefore, the registration sensor detected at the time of the development of the first color is detected. The signal A, the registration roll detection signal B, and the paper detection signal C are not generated. However, the size of the paper 2 in the sub-scanning direction can be known by referring to the paper detection signal C obtained during the development of the first color. Therefore, the control device 12 outputs the paper size signal J, which is set in advance to a fixed value in association with the paper size, with reference to the paper detection signal C. That is, if it is determined from the width of the paper detection signal C that the size of the paper 2 is the A4 landscape size, the paper size signal J stored in advance in the storage means in the controller 12 in association with the A4 landscape size. Is output. Then, the image valid signal D is generated based on the paper size signal J.

On the other hand, the image data signal F is fetched with a delay of a predetermined delay time D3 from the transfer drum reference signal E, as in the case of the first color development. Then, the image valid signal D is used as a gate signal to erase the rear end of the image data signal F, and finally the image data signal G to be written is obtained. The subsequent operation is the same as in the case of the first color development, and therefore the description is omitted.

[0010]

By the way, in such a conventional apparatus, as described above, there is a problem that a color shift occurs between the first color and the second and subsequent colors, especially at the trailing edge of the paper. It was That is, in the conventional device, the first
At the time of developing the color, the image valid signal D for performing the trailing edge erasing process of the image data signal F is directly generated from the sheet detection signal C, whereas in the second and subsequent colors, the sheet detection signal C is generated. However, it is created based on the paper size signal J preset to a constant value. Therefore, the length of the image effective signal D is slightly different between the first color and the second and subsequent colors, and the position of the trailing edge erasing process is different, so the length of the image data signal G to be written is also different. Therefore, color misregistration (a portion where only the first color is developed,
Alternatively, a portion in which only the first color is missing) occurs.

The present invention has been made to solve the above-mentioned problems. Even when the paper is fed from the manual feed tray, the positions of the trailing edge erasing processes can be accurately unified for all the colors so that the color misregistration is prevented. It is an object of the present invention to provide a color image processing device capable of eliminating the above.

[0012]

Therefore, in the color image processing apparatus of the present invention, the manual feed tray, the paper detection means for detecting the start and end of the paper inserted from the manual feed tray, and the paper detection means Image valid signal creating means for creating an image valid signal based on the output, clock counting means for counting the clock signal over a predetermined period, and the image valid signal from the time of generation of the reference signal at the time of developing the first color material. Storage means for storing the count value of the clock counting means up to the fall time of, and the black cook count in synchronization with the generation of the reference signal during the development of all the color materials after the second color material. When the clock signal is counted up to the count value stored in the storage means, the developing drum It is characterized in the write image information for that and a control means for stopping.

[0013]

In the present invention, the period corresponding to the image effective signal D of the first color is stored as the count value of the clock signal,
For the second and subsequent colors, the trailing edge erase timing of the image data, that is, the trailing edge erase timing of the image data is determined based on the stored count value.
The trailing edge erasing timing of the image data signal can be accurately unified for the color and the second and subsequent colors, and the color shift at the trailing edge of the paper can be prevented.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a structural example of the entire color image processing apparatus of the present invention, and FIG. 2 is a time chart showing its operation. 1, the same numbers as those in FIG. 4 represent the same contents as those in FIG. In FIG. 1, 13 is an encoder (clock pulse generator) that outputs a clock signal H in synchronization with the rotation of the transfer drum 10, and 14 is a counter (clock counting means).

In the embodiment shown in FIG. 1, when the sheet 2 is supplied from the manual feed tray 1, the sheet 2 passes through the registration sensor 3 and the registration roll 4 and is attached to the transfer drum 10.
On the other hand, the color image signal read by the image reading device 6 is input to the control signal 12, and is written on the developing drum 8 from the ROS 7 for each color. Then, the coloring material is placed on the developing drum 8 from the corresponding toner supply device 9, and the developing material is sequentially superposed on the paper 2 on the transfer drum 10 for development processing. The reference signal detector 11 detects a reference signal generated at a predetermined rotation position of the transfer drum 10 and inputs it to the control device 12 as a signal E. Further, the registration roll detector 5 detects whether or not the sheet 2 is present at the position of the registration roll 4 and outputs a signal B, which is input to the control device 12 together with the detection signal A of the registration sensor 3.

Up to this point, the apparatus is similar to that of FIG. 4, but in the present embodiment, an encoder 13 that outputs a clock signal H in synchronization with the rotation of the transfer drum 10 and a clock signal that the encoder outputs are further provided. A counter 14 for counting the number of H based on a command from the control device 12 is provided.

Next, based on the time chart of FIG.
The operation of this embodiment will be described. When the paper 2 is supplied from the manual feed tray 1 and passes the registration sensor 3, the paper 2
A registration sensor detection signal A which rises when the registration sensor 3 is entered and falls when the registration sensor 3 is exited
Occurs. When the paper 2 approaches the position of the registration roll 4, the registration roll detector 5 generates a registration roll detection signal B that rises when the paper 2 enters the registration roll 4 and falls when the paper 2 exits the registration roll 4. The registration sensor detection signal A and the registration roll detection signal B are input to the control means 12, and the logical product (AND) of the signals A and B is taken inside the control device 12 to obtain the paper detection signal C (= A * B). Is created. That is, the paper detection signal C is a signal that rises in synchronization with the rise of the registration roll detection signal B and falls in synchronization with the fall of the registration sensor detection signal A, and is manually inserted at the positions of the registration sensor 3 and the registration roll 4. The size of the paper 2 in the sub-scanning direction is detected.

Next, an image valid signal D is created by delaying the rising and falling edges of the paper detection signal C by a predetermined delay time D1 and D2, respectively. The image valid signal D is a gate signal that determines the time range in which the read image signal F is validated, and varies depending on the size of the supplied paper. The reason why such a signal D is generated is to prevent the color material from being deposited on the developing drum 8 beyond the size of the sheet, and thereby to prevent the toner from being transferred onto the transfer drum 10. There is. From the registration roll position where the paper detection signal C is detected,
Since there is a physical distance to the position of the developing drum 8 / transfer drum 10 to which an image is transferred, the delay time D
It is set as 1 and D2.

On the other hand, with the rotation of the transfer drum 10,
The transfer drum reference signal E generated at a predetermined position is detected by the reference signal detector 11 and input to the control device 12.
The control device 12 delays the transfer drum reference signal E by a predetermined delay time D3 and takes in the image data signal F. Then, the image valid signal D is used as a gate signal to erase the rear end of the image data signal F. That is, the trailing edge of the image data signal F is forcibly cut off at the trailing edge of the image valid signal D, and the signal from which the trailing edge is cut off is actually written into the image data signal G (= D
* F) is given to ROS7. After that, the ROS 7 irradiates the developing drum 8 with a laser beam in accordance with the image data signal G, and the color material of the first color is placed on the developing drum 8 from the toner supply device 9 and transferred onto the sheet 2. .

The operation up to this point is the same as that described with reference to the time chart of FIG. 5, but in the present embodiment, the counter 1 is further operated from the time when the transfer drum reference signal E is generated.
4 is operated to count the number of transfer drum clock signals H generated by the encoder 13. The counting operation by the counter 14 is continued until the fall of the image valid signal D, and the value of the final count value N at that time is stored and held in the storage means inside the control device 12.
The above is the operation when developing the first color.

Next, the operation of the developing process for the second and subsequent colors will be described. At the time of developing the second color and thereafter, the paper 2 is already placed on the transfer drum 10 and does not pass the positions of the registration sensor 3 and the registration roll 4. Therefore, the registration sensor detected at the time of the development of the first color is detected. The signal A, the registration roll detection signal B, and the paper detection signal C are not generated. Therefore, conventionally, the size of the paper 2 is determined by referring to the paper detection signal C obtained during the development of the first color, and the paper size previously set to a fixed value in association with the paper size. Signal J was provided by controller 12,
In the present embodiment, such a preset paper size signal J is not used. Instead, when the transfer drum reference signal E is generated, the counter 14 is activated to count the transfer drum clock signal H of the encoder 13.

On the other hand, the image data signal F is fetched with a delay of a predetermined delay time D3 from the transfer drum reference signal E, as in the case of the first color development. However, at this time, the falling time of the image valid signal D has not been determined, while the counting operation of the counter 14 continues. In the counting operation, the control device 12 constantly compares the final count number N stored and held in the storage means with the value of the output signal I of the counter 14. Then, when the value of the output signal I of the counter 14 becomes equal to the final count number N, the control device 12 causes the image valid signal D to fall, and at the same time, performs the trailing edge erasing process of the image data signal F. , The image data signal G to be finally written is obtained. The subsequent operation is the same as in the case of the first color development, and therefore the description is omitted. Further, the development of the third color and thereafter is performed in the same manner as the second color.

As described above, in this embodiment, the trailing edge of the image valid signal D for the second and subsequent colors is not determined by a predetermined constant value, but the image valid obtained during the development of the first color is validated. Since the determination is made based on the clock count number corresponding to the signal D, the first color development and the second color development are performed.
It is possible to accurately unify the time points of the trailing edge erasing processing of the image data signal F in the development of all the colors and after.

The present invention is not limited to the above embodiment, but various modifications are possible. For example, in the above embodiment, the rotary toner supply device 9 is provided, and one developing drum and one transfer drum are provided, but a tandem type as shown in FIG. 3 is also applicable. Is. That is, a dedicated ROS for each color
71-74, toner supply devices 91-94, developing drum 8
1 to 84 are provided, and each color is developed while the sheet 2 is flowed from the right side to the left side of the drawing. In this case, the first
Of the second end of the image data signal generated by the count value of the clock signal of the developing drum 81 of
It may be applied to the developing drum 82 and after.

[0025]

As is apparent from the above description, according to the present invention, the period corresponding to the image effective signal D of the first color is stored as the count value of the clock signal, and for the second and subsequent colors, Since the trailing edge erase timing of the image data, that is, the trailing edge erase timing of the image valid signal is determined based on the stored count value, the first color and the second color
It is possible to provide a color image processing apparatus capable of accurately unifying the trailing edge erasing timing of the image data signal for the color and subsequent colors and preventing color misregistration at the trailing edge of the paper.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a time chart showing the operation of the embodiment of the present invention.

FIG. 3 is a block diagram showing a main configuration of another embodiment of the present invention.

FIG. 4 is a block diagram showing a conventional color image processing apparatus.

FIG. 5 is a time chart showing the operation of a conventional color image processing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bypass tray, 2 ... Paper, 3 ... Registration sensor, 4 ... Registration roll detector, 5 ... Registration roll detector, 6 ... Image reading device, 7 ... ROS, 8 ... Development drum, 9 ... Rotary toner supply device, 10 ... Transfer drum , 11 ... Reference signal detector, 1
2 ... Control device, 13 ... Encoder, 14 ... Counter.

Claims (1)

[Claims] 1. A manual feed tray, paper detection means for detecting the start and end of a paper inserted from the manual tray, and image valid signal creation means for creating an image valid signal based on the output of the paper detection means. A clock count means for counting the clock signal over a predetermined period, and a count value of the clock count means during the development of the first color material from the generation of the reference signal to the fall of the image valid signal. And a storage means for storing all the color materials after the second color material, and during the development of all the color materials after the second color material, the counting operation by the clock cook counting means is performed in synchronization with the generation of the reference signal, and is stored in the storage means. A control means for stopping writing the image information to the developing drum when the clock signal is counted up to the count value is provided. Color image processing apparatus according to.