JPH05212913A - Image forming device - Google Patents

Abstract

PURPOSE:To use an image memory with a good efficiency and to shorten a processing time without increasing the capacity of the image memory by a method wherein the image memory is dividedly used in accordance with the resolving power of an image and the size of printing paper. CONSTITUTION:An image development part of an image forming device is provided with an image memory 13 for storing image data in a dot matrix form; a frame buffer development means 21 for developing the image data for one frame all over the image memory; a double buffer development means 22 for dividing the image memory into two parts and successively developing image data for one frame on either a divided image memory 13A or 13B in the image memory per frame; an image memory division change-over means 23 for changing over one of the aforesaid two development means to the other; and a change-over condition setting means 24 for setting a change-over condition in the image memory division change-over means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having an image memory for expanding bitmap data.

[0002]

2. Description of the Related Art In recent years, due to advances in print recording technology and digital signal processing technology, image forming apparatuses such as printers tend to have high image quality (high resolution and high gradation). An example of such a high quality image forming apparatus is a page printer having an image memory for developing and storing image information data. However, in order to meet the above demands, it is feared that the processing for image generation will take a long time, and the capacity of the image memory will be increased.

A conventional page printer having an image memory will be described below with reference to FIGS. 5 and 6. FIG. 5 shows a block diagram of an image developing unit in the printer controller, and FIG. 6 shows a flowchart of image data developing processing.

In FIG. 5, when a data code sent from the host side such as a computer is received, the page memory frame buffer expansion means 101 interprets the data code and expands and writes the image data in the image memory 102. Then, the data written in the image memory 102 is sent as a video data signal to the printer engine side by the image data signal output means 103 which is an engine transfer synchronizing means for synchronizing with the printer engine.

Further, in the page memory frame buffer expansion means 101, when interpreting the data code and expanding it in the image memory, the procedure is as follows (see FIG. 6).

(1) It is determined whether the data code is related to image development. (2) If the data code is related to image expansion, the bitmap data is expanded in the image memory until the page end code is received.

The conventional page printer described above has
This is a frame buffer expansion method that is allocated only as an image memory for pages, and the expansion processing of the image data of the next page cannot be started until the expansion of bitmap data is completed and the image data signal is output. It is a thing.

[0008]

As described above, in the conventional frame buffer expansion method of the image memory in the page printer, only the image memory for one page is allocated, and the expansion processing for one page must be completed. , There is a problem that the output time of the next page, that is, the processing time becomes long because it cannot be included in the expansion processing of the next page, and when trying to have the image memory for multiple pages,
There was a problem that the image memory had to be increased.

Therefore, the present invention is intended to solve the above problems, and an object thereof is to speed up the processing time of image data while suppressing an increase in the image memory.

[0010]

In order to achieve the above object, an image forming apparatus of the present invention is an image forming apparatus having an image developing section for developing a data code sent from a host side into image data. An image memory for storing image data in a dot matrix form in the image developing unit,
A frame buffer expansion means for expanding one frame of image data in the entire image memory, and dividing the image memory into a plurality of units, and one frame of image data
A multi-buffer expansion means for sequentially expanding each of the divided image memories and for each frame, an image memory division switching means for switching to either of these expansion means, and a switching condition for the image memory division switching means are set. The switching condition setting means for setting is provided.

Further, in the above construction, the image resolution is used as the switching condition, and in the above construction, the image output paper size is used as the switching condition.

[0012]

According to the above construction, the image memory in the image developing unit can be selected from a frame buffer system capable of developing one frame and a multi-buffer system capable of developing a plurality of frames. By setting the resolution and the size of the output paper as the switching conditions, it is possible to efficiently use the image memory according to the low resolution which is frequently used or the size of the small paper.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to an embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a view showing the schematic arrangement of the image forming apparatus according to this embodiment. In FIG. 1, reference numeral 1 denotes an image forming apparatus such as a page printer, which develops a data code 5 sent from a host computer 4 as image data and converts it into an image recording signal 6, and an image recording unit 2. The printer engine 3 forms a recorded image 7 from the signal 6.

As shown in FIG. 2, the image processing unit 2 communicates with the host computer 4 and receives a data code 5 and a communication interface 11 that interprets the received data code and also outputs image data as bitmap data. The image expansion unit 12 for expanding the bitmap data for writing the information in the image memory 13 which is expanded and stored in the dot matrix form, and the image data from the image memory 13 are converted according to the resolution and the number of gradations of the image. And an image reading unit 14 that performs processing for improving the image quality of binary characters and line drawings, and processing for stabilizing the gradation in the printer engine 3 in addition to processing such as image density adjustment and gamma correction. It comprises an engine interface 15 for sending the output signal from the image reading section 14 to the printer engine 3. To have.

Next, the image developing section and the image memory section, which are the gist of the present invention, will be described with reference to FIG.
FIG. 3 is a block diagram of the image expansion writing process.

That is, the image expansion unit 12 divides the image memory 13 into two and a frame buffer expansion means 21 for expanding image data for one frame into the entire image memory, and an image for one frame. A double buffer expansion means 22 for expanding data in any of the divided first and second divided image memories 13A and 13B and sequentially for each frame is provided, and is switched to either of the above expansion means 21 and 22. Image memory division switching means 23 is provided, and switching condition setting means 24 for setting this switching condition is further provided.

The image data in the image memory 13 is read by the image data signal output means 31 and output to the printer engine 3 side. At this time, the output timing switching means 32 changes the resolution of the image data. The output timing of the image data is switched accordingly.

The image data signal output means 31 is
It is an engine transfer synchronizing means for synchronizing with the printer engine 3 and sends it as a video data signal to the printer engine 3 side, and corresponds to the image reading section 4 and the engine interface 5 in FIG.

By the way, the switching condition setting means 24 is adapted to switch to any one of the developing means 21, 22 according to the resolution of the image and the size of the output paper.

Now, the switching condition will be described. (1) When the switching condition is resolution For example, when the resolution is 600 dpi, the image memory division switching means 23 selects the frame buffer expansion means 21 to expand the image data in the memory space of the entire image memory 13. To be done.

When the resolution of the image data is 300 dpi, the double buffer expansion means 22 is selected, the image memory 13 is divided into two, and two frame buffers appear. Therefore, after the image data of the first page is expanded in the first divided image memory 13A, the image data of the second page is output while the image data is being output to the printer engine 3 by the image data signal output means 31. Is expanded in the second divided image memory 13B. Further, while the image data from the second image memory 13B is being output, the image data is expanded in the first image memory 13A. When 600 dpi is selected, the output timing switching means 32 switches the timing to 600 dpi and the image data signal output means 31 outputs the image data to the printer engine 3.

(2) When the switching condition is the paper size For example, when the paper size is A3, the image memory division switching means 23 selects the frame buffer expanding means 21 to make the entire memory space of the image memory 13. Image data is expanded.

When the paper size is A4, the double buffer expansion means 22 is selected, the image memory 13 is divided into two, and two frame buffers appear. Then, as in the case of (1) above, after the image data of the first page is expanded in the first divided image memory 13A, this image data is output to the printer engine 3 by the image data signal output means 31. In the middle, the image data of the second page is expanded in the second divided image memory 13B. Further, while the image data from the second image memory 13B is being output, the image data is expanded in the first image memory 13A.

As described above, it is possible to select the image memory expansion method according to the resolution and / or the paper size. Next, the actual processing in the image developing unit 12 will be described with reference to the flowchart shown in FIG.
Since the expansion portion of the image memory has already been described in detail, in this description, a schematic process of the entire image expansion portion will be described.

(1) The switching condition setting means 24 sets the switching conditions for the image development method. For example, the resolution is 600d
The paper size is set to pi and A3 and B4. (2) When the image memory is selected by the frame buffer expansion method as the switching condition, the same operation as the conventional printer is performed without dividing the image memory.

(3) When the switching condition is such that the image memory is selected by the double buffer expansion method, the image memory is divided into the first
After the bitmap data is expanded in the divided image memory 13A or the second divided image memory 13B, the image data is sent out from the divided image memory, and during this sending, the image data is expanded as bitmap data in the remaining divided image memories. It Further, the above series of expansion operations are repeated as long as there is a page of image data in the data reception buffer.

(4) From the image memory 13 to the printer engine 3
The timing of sending the image data to the side is set by the output timing switching means 32, and the timing is switched only when the resolution is switched. Then, the image data read from the image memory 13 is output to the printer engine 3 as a video data signal (image recording signal) in synchronization with the printer engine 3 at the timing of the output timing switching means 32.

That is, depending on the resolution and / or the paper size information of the image data sent from the host computer, whether the image expansion method is the frame buffer expansion method or the double buffer expansion method is used. In consideration of the above, an advantageous method can be selected.

Although the image memory is divided into two in the above embodiment, the number of divisions is not limited to two.

[0031]

As described above, according to the configuration of the present invention, it is possible to select the frame buffer system capable of developing the image memory in the image developing unit as one frame and the multi-buffer system capable of developing as a plurality of frames. Therefore, for example, by setting the resolution and the size of the output paper as the switching conditions, the image memory can be used more efficiently for the lower resolution or the smaller paper size that is frequently used, and therefore, from multiple pages. Image data, without increasing the image memory capacity,
The processing time can be shortened. That is, it is possible to simultaneously develop the image data in the image memory and output the image memory.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic overall configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of an image processing unit in the image forming apparatus of the embodiment.

FIG. 3 is a block diagram illustrating a configuration of an image expansion unit in the image processing unit of the embodiment.

FIG. 4 is a flowchart illustrating a process of expanding image data in an image memory according to the embodiment.

FIG. 5 is a block diagram illustrating a configuration of an image expansion unit in a conventional example.

FIG. 6 is a flowchart illustrating a process of expanding image data in an image memory according to a conventional example.

[Explanation of symbols]

 1 Image Forming Device 2 Image Processing Unit 3 Printer Engine 4 Host Computer 5 Data Code 6 Image Recording Signal 7 Recorded Image 11 Communication Interface 12 Image Development Unit 13 Image Memory 14 Image Reading Unit 15 Engine Interface 21 Frame Buffer Development Unit 22 Double Buffer Development Means 23 Image memory division switching means 24 Switching condition setting means 31 Image data signal output means 32 Output timing switching means

Claims (3)

[Claims] 1. An image forming apparatus having an image expanding unit for expanding a data code sent from a host side into image data, wherein the image expanding unit stores an image data in a dot matrix form. A frame buffer expansion means for expanding one frame of image data in the entire image memory, and dividing the image memory into a plurality of pieces, and one frame of image data in any of the divided image memories. Further, there are provided a multi-buffer expansion means for sequentially expanding each frame, an image memory division switching means for switching to either of these expansion means, and a switching condition setting means for setting a switching condition of the image memory division switching means. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the image resolution is used as the switching condition. 3. The image forming apparatus according to claim 1, wherein the size of the image output paper is used as the switching condition.