JPH09231035A - Data transfer method - Google Patents

Abstract

(57) Abstract: A data transfer method that eliminates the need to mount a large-capacity image memory inside a color printer and does not create a wasteful part in the main memory of a host computer. A host computer 10 tries to transfer four-color parallel image data to a color printer 20.
At this time, when the data to be transferred is expanded in the main memory 12 of the host computer 10, each parallel data is expanded in the main memory 12 by shifting by the delay of the output timing, and the expanded data is folded back. The main memory 12 is prevented from being wasted.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a data transfer system,
More specifically, it relates to a data transfer method for transferring a color image from a host computer to a color printer.

[0002]

2. Description of the Related Art Conventionally, when transferring image data to a four-drum type photosensitive drum type color printer, depending on the position of the photosensitive drum, even if the data is at the same point, the writing timing of the data of each color to the drum is set. Need to give each delay. As a method of realizing this delay,
In the conventional system, for example, in the system disclosed in Japanese Patent Laid-Open No. 62-284369, when the delay from the reference signal is counted by the counter, the number of counters corresponding to each drum is made different for each drum. This is because in the case of continuous paper feeding, the registration signal of the reference color is continuously output, so the registration signal of the reference color is output before the registration of the drum with a large delay starts.
A plurality of counters are prepared and switched to enable high-speed continuous paper feeding.

In the above-mentioned conventional technique, the output timing of each color is delayed according to the delay. However, when the same point is transferred from the host computer or the scanner at the same timing for each color, further measures are required. Figure 7
Is a diagram showing a method of data transfer to a conventional four-series photoconductor drum type color printer at the same point and the same timing for each color. Image data transferred from a host computer or a scanner at the same point and for each color at the same timing, black. The data Bk, the magenta data M, the yellow data Y, and the cyan data C are the photosensitive drums 2 of the respective colors.
3Bk to 23C. Here, if the paper 22 is conveyed on the conveyance path 21 from the top to the bottom, in order to fix the toner of the same point data of four colors to the same point of the paper 22, the paper 22 is attached to each photosensitive drum. Time to be transported,
You need to give a delay.

In order to give this delay, the magenta data M, the yellow data Y and the cyan data C are image memories 24M and 24 provided for each color according to the delay.
The data is temporarily buffered in Y and 24C, and is transferred to each photoconductor drum with a delay timing for each color. By adjusting this delay timing, the paper 22
The toner of the same point data of four colors is fixed to the same point of.
With these configurations, the image data can be transferred to the color printer of the 4-drum type photosensitive drum system.

The theoretical value of this delay value can be obtained from the shape and arrangement of the photosensitive drums. However, in order to accurately fix the same point data of four colors to the same point on the paper, the delay value is empirically determined. Need to ask. As a conventional technique for obtaining the value of this delay, for example, in the method disclosed in Japanese Patent Laid-Open No. 62-242969, each photosensitive drum corresponds to each region of a sheet divided into a plurality of parts in the main scanning direction. By forming an image, detecting the relative positional deviation of each image, and correcting the color misregistration, it is possible to accurately fix the same point data of four colors to the same point on the paper.

[0006]

The memory size of the image memory required to realize the delay as in the above-mentioned prior art is one image element of one color of 8 bits and a pixel density of 400 dp.
i, the distance between the photoconductor drums 23Bk to 23C is about 10 cm, and when A4 size paper is conveyed in the vertical direction, the image memory 24C has (300 mm × 400 dpi / 25.4 mm / inch) × (297 mm × 400 dpi / 25.4) mm
/ inch) × 8bit / dot = Approximately 21MBytes capacity is required.

As described above, the conventional method requires a large-capacity image memory to realize the delay. When transferring data from the host computer, the image data has already been expanded in the main memory, and if a large-capacity image memory is installed inside the printer, the memory will be used twice and a great cost will be required. There was a problem of doing.

[0008]

According to a first aspect of the present invention, data is transferred from a host computer to a device which outputs parallel data and which needs to be provided with a constant delay in output timing between the parallel data. In the transfer method, when the data to be transferred is expanded in the main memory of the host computer, each parallel data is expanded in the main memory by shifting by the delay of the output timing, and the expanded data is folded back. By doing so, it is possible to prevent useless portions from being generated in the main memory.

According to a second aspect of the present invention, in the first aspect of the present invention, blank portions are inserted at regular intervals of the data to be expanded in the main memory, and the delay value of the output timing is made variable so that the main memory is changed. It is possible to adjust the delay value of the output timing without re-expanding the data to the main memory by expanding the data to the device and suppressing the blank portion when transferring the data to the device. It is a thing.

[0010]

1 is a block diagram for explaining an embodiment of a data transfer system according to the present invention. When a host computer 10 tries to transfer 4-color parallel image data to a color printer 20, First, the CPU 11 expands the color image data stored in the main memory 12 into a data transfer area. According to the first aspect of the present invention, at this time, the CPU 11 fixes the same point color image data of the photosensitive drums 23Bk to 23C in the color printer 20 to the same point of the paper 22 conveyed on the conveyance path 21. The data is converted into a form shifted by the delay value adjusted as described above, and the image data is transferred to the color printer 20. The color printer 20 transfers the transferred image data to the photoconductor drums 23Bk to 23C of the respective colors. Here, since each color data of the same point is given a predetermined delay before being transferred from the host computer 10, the color printer 20 does not need any memory for buffer, and the color data of the paper 22 is the same. The toner of the same point data of four colors is fixed to one point.

FIGS. 2 and 3 are diagrams for explaining data conversion for giving a predetermined delay performed by the CPU 11. In order to simultaneously transfer image data of four colors from the host computer to the color printer 20, black ( K1
K4), magenta (M1 to M4), yellow (Y1 to Y)
4) and each data of cyan (C1 to C4) has a data width of 1/4 of the data bus width of the system. For example, in a system having a data bus width of 32 bits, 8-bit data for each color can be transferred simultaneously.

2 and 3 show the main memory 12 in FIG.
In the drawing, each color image data is developed, and in the horizontal direction, each square has 8 bits, and the total bit width is 32 bits. Black K, magenta M, Indicates that the data of yellow Y and cyan C are stored. In the vertical direction, one cell represents the amount of data for one color of delay. Data names representing image data have alphabets (Bk or K: black), (M: magenta), (Y: yellow), (C:
(Cyan), and the subscript numbers represent data at the same point in each color. For example, (K1, M1, Y1, C
The image data of 1) represents each color image data at the same point in a certain fixed area, and the amount of data is the amount of delay for one color.

Here, when the image data is to be transferred to the color printer 20 at the same timing for each color of the same point in order to realize a desired delay, as shown in FIG.
Each image data is shifted backward by the delay amount, as shown in FIG.
The blank portion above is useless data that is not used even if transferred to the color printer 20.

Therefore, as shown in FIG. 3, the data which is displaced rearward due to the delay is folded back to the upper blank portion to be developed. In this case, the colors not read by the color printer 20 (M4, Y when outputting K1)
3, C2) are masked so as not to be transferred to the color printer 20.

The above-mentioned function is performed by the output control device 13 shown in FIG.
Realized by. In FIG. 3, (K4, M3, Y2, C
When the data transfer of 1) is completed, (K1, M4, Y
3, C2) data transfer is performed. At this time, since K1 is masked, it is not transferred to the color printer.
By transferring each data to the color printer twice each up to (K3, M2, Y1, C4), (K1, M1, Y)
1, C1) to (K4, M4, Y4, C4) is completed.

With the above configuration, it is possible to mount a large-capacity buffer image memory in the color printer 20,
The 4 parallel image data can be transferred from the host computer, and the image data can be expanded without generating a useless portion on the main memory.

FIGS. 4, 5, and 6 are views for explaining the invention of claim 2. In FIG. 6, the same reference numerals as those in FIG. 1 carry out the same operations as those in FIG. I shall. Further, in FIGS. 4 and 5, the meanings of characters and figures are the same as those in FIGS. 2 and 3. With the configuration similar to that of the first aspect of the invention, it is possible to transfer the color data by giving a desired delay to the color printer. However, when the color image data is expanded on the main memory as shown in FIG. It is necessary to re-expand the data each time the delay value changes. As described above, it is necessary to empirically find the delay value in order to accurately fix the same point data of four colors to the same point on the paper. In this case, if the data is expanded again each time the delay value is changed, it takes time for expansion each time. Therefore, in the invention of claim 2, blank portions are inserted at regular intervals of data to be expanded in the main memory.

In FIG. 4, the shaded area is a blank area. When the image data expanded in the main memory in this way is transferred to the color printer with a delay as shown in FIG. 5, for example, the transfer is performed between each color by further providing a delay by the size of the halftone dot portion in the drawing. There is a need.
Therefore, as shown in FIG. 6, an output control buffer 14 is provided between the main memory 12 and the output control device 13, and the delay between the colors is buffered and output to the output control device 13. The output control buffer 14 has a much smaller size than the conventional image buffer image memory such as the image memories 24Y, 24M, and 24C shown in FIG. Further, the output control device 13 controls the output so that the blank portion is not output to the color printer 20, and only the image data is transferred to the color printer 20.

[0019]

According to the first aspect of the present invention, when the four-color parallel image data is transferred from the host computer to the color printer of the four-drum type photosensitive drum system, a delay is applied before transferring the data. Since the image data is expanded in the memory and the expanded data is folded back, it is not necessary to mount a large-capacity image memory inside the color printer, and a wasteful part does not occur in the main memory of the host computer.

According to the second aspect of the present invention, blank portions are inserted at regular intervals in the data to be expanded in the main memory, and the blank portions are suppressed when the image data is transferred to the color printer. The delay value of the output timing can be adjusted without re-expanding the data in the memory.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a data transfer system according to the present invention.

FIG. 2 is a diagram showing an example of developing image data in a main memory.

FIG. 3 is a diagram showing an example of developing image data in a main memory.

FIG. 4 is a diagram showing an example of developing image data in a main memory according to the present invention.

FIG. 5 is a diagram showing an example of developing image data in a main memory according to the present invention.

FIG. 6 is a configuration diagram for explaining another embodiment of the data transfer system according to the present invention.

FIG. 7 is a configuration diagram for explaining an example of a conventional data transfer method.

[Explanation of symbols]

10 ... Host computer, 11 ... CPU, 12 ... Main memory, 13 ... Output control device, 14 ... Output control buffer, 20 ... Color printer, 21 ... Conveying path, 22 ... Paper, 23Bk-23C ... Photosensitive drum, 24M , 24
Y, 24C ... Image memory.

Claims (2)

[Claims] 1. A data transfer method for transferring data from a host computer to a device which outputs parallel data and which is required to provide a constant delay in output timing between respective parallel data, in a main memory of said host computer. Further, when the data to be transferred is expanded, each parallel data is expanded in the main memory by shifting by the delay of the output timing, and the expanded data is folded back so as not to cause a wasteful part in the main memory. A data transfer method characterized in that 2. The device according to claim 1, wherein blank portions are inserted at regular intervals of data to be expanded in the main memory, the delay value of the output timing is changed and expanded in the main memory, and the data is expanded to the device. A data transfer method, wherein a blank value is suppressed when data is transferred, so that the delay value of the output timing can be adjusted without re-expanding the data in the main memory.