JP2000231473A - Display controller and method for data transfer to display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display controller to reduce data transfer quantity and to enable high speed display. SOLUTION: In a copier main body 100, image data to be displayed on an LCD 300 is plotted in a VRAM 103 by a main CPU 101, the image data plotted in the VRAM 103 is transferred to an LCDC 201 as separate windows by a DMAC 102. On the other hand, in an operation display part 200, the image data transferred from the DMAC 102 is written by using one of two frame memories provided in a frame memory 202 using it for writing and, in addition, image data stored in the other frame memory of the frame memory 202 is read, transferred to the LCD 300, displayed there by using the other frame memory for display and the roles of two memories are switched by the LCDC 201.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display control device and a data transfer method to a display device, and more particularly, to a display control device for displaying an image on a display device in a copying machine or the like, and a data transfer method to the display device. About.

[0002]

2. Description of the Related Art FIGS.
FIG. 4 is a diagram for explaining a conventional technique relating to an interface with an operation display unit using a CD or the like. 13, reference numeral 500 denotes a copying machine main body; 600, an operation unit display unit;
0 indicates an LCD. The copying machine body 500 includes a CPU 5
01, a communication control unit 502 is included. The operation display unit 600 includes a communication control unit 601, a CPU 602, and an LCD.
C (LCD controller) 603 and VRAM 604.

In the copying machine having the above configuration, a drawing command for the LCD 700 is transferred from the copying machine body 500 to the operation display unit 600 by serial communication, and the operation display unit 60 is operated.
0 interprets the drawing command by the CPU
Draw on.

In FIG. 14, reference numeral 800 denotes a copying machine main body, and 900 denotes an operation display unit. Copying machine body 800
Includes a CPU 801, an LCDC 802, and a VRAM 803. The operation display unit 900 includes an LCD 901.

[0005] In the copying machine having the above structure, the copying machine body 800 directly draws the image on the VRAM 803, then transfers the video data to the operation display unit 900, and sends the video data to the operation display unit 90.
0 is displayed on the LCD 901.

[0006]

However, in the prior art shown in FIG. 13, since drawing is performed at the command level, the CPU 501 of the copier main body 500 frequently transmits transmission interrupts from the communication control unit 502. Enters,
The burden of serial communication becomes heavy for CPU 501,
There is a problem that it affects other processing (the original processing of the copying machine).

In the prior art shown in FIG. 14, since the drawing is performed directly in the VRAM 803, the load of the communication interrupt is reduced, but the data transfer rate between the copier body 800 and the operation display unit 900 is increased. There is a problem in terms of noise emission and transfer accuracy.

[0008] The present invention has been made in view of the above, and an object of the present invention is to provide a display control device capable of reducing a data transfer amount and performing high-speed display, and a method of transferring data to a display device.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, in a display control device for transferring image data from a device main body to a display device for display, the device main body comprises:
First storage means for storing image data, data drawing means for drawing image data to be displayed on the display device in the first storage means, and image data drawn in the first storage means A data transfer unit for transferring data to the display device side in window units, wherein the display device displays image data; a second storage unit including at least two frame memories; Writing means for writing image data transferred from the data transfer means, using one frame memory of the storage means for writing;
The other frame memory of the storage means is used for display,
A reading unit that reads out the image data stored in the other frame memory and displays the image data on the display unit; and a switching unit that switches roles of the at least two frame memories.

According to a second aspect of the present invention, in the first aspect of the present invention, the display device further includes an image data stored in the frame memory switched for display by the switching means. Is transferred to the frame memory switched for writing.

According to a third aspect of the present invention, in the second aspect of the present invention, the display device further includes an image data stored in the frame memory switched for display by the switching means. To the first storage means of the apparatus main body.

The invention according to claim 4 is the invention according to claims 1 to
3. The invention according to claim 3, wherein the first storage means is provided so as to allow simultaneous multi-bit access, and the data drawing means stores the image data in the first multi-bit The writing is performed, and the data transfer unit reads out the image data drawn in the first storage unit, converts the image data into the data width of the transfer bus, and transfers the data to the display device.

According to a fifth aspect of the present invention, there is provided a data transfer method for transferring image data from a device main body to a display device to a display device for displaying the image data, the first device provided on the device main body side. Drawing in the storage means image data to be displayed on the display device; transferring the image data drawn in the first storage means from the device body to the display device; A step of writing image data transferred from the apparatus body side using one of the frame memories for writing, and a step of reading image data stored in the other frame memory using the other frame memory for display and displaying the image data. And switching the roles of the at least two frame memories.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, a preferred embodiment of a copying machine to which a display control device and a method of transferring data to a display device according to the present invention are applied will be described (Embodiment 1). (Embodiment 2) and (Embodiment 3) will be described in detail in this order.

(Embodiment 1) Embodiment 1 is shown in FIGS.
This will be described with reference to FIG. FIG. 1 is a diagram showing a schematic configuration of a display system of a copying machine. The display system of the copying machine shown in FIG. 1 includes a copying machine main body 100, an operation display unit 200, and an LCD 300 including an STN, a TFT, and the like. The copier body 100 and the operation display unit 200 are connected by a transfer bus.

The main body 100 of the copying machine includes a CPU 101 for controlling each part of the copying machine, a DMAC (DMA controller) 102 for DMA-transferring image data stored in a VRAM 103 to an operation display unit 200, and an LCD 3.
VRAM 10 in which image data to be displayed at 00 is drawn
3 are connected via a bus 104.

The operation display unit 200 includes an LCDC (Liquid Crystal Display Controller) 2 for controlling display of the LCD 300.
01, for writing (for buffering) image data transferred from the copying machine main body 100 (DMAC 102) and for LCD
It comprises a frame memory 202 used for display on 300. The frame memory 202 includes two frame memories (capacity for two screens) 202A and 202B (see FIG. 2). Two frame memories 202A, 2
02B is used for writing (buffering) image data transferred from the copying machine main body 100 and for displaying on the LCD 300. This switching is performed by the LCDC 201.

Next, the LCD of the copying machine shown in FIG.
An outline of the display operation on the display 300 will be described. First, the main CPU 101 of the copying machine main body 100 directly draws image data to be displayed on the LCD 300 on the VRAM 102.
The rendered image data is transferred to the operation display unit 200 via the transfer bus 400 by the DMA controller 103.
Will be transferred. In the operation display unit 200, the transferred image data is stored in the frame memory 202 via the LCDC 201.
Is stored in Then, the image data stored in the frame memory 202 is read out by the LCDC (Liquid Crystal Display Controller) 201 and displayed on the LCD 300.

FIG. 2 shows the DMAC 10 of the copier main body 100.
FIG. 5 is an explanatory diagram for describing data transfer of No. 2 in detail;
Data transfer of the DMAC 102 is performed in units of windows to be drawn.

The frame memory 202 of the operation display unit 200
Has two frame memories (memory capacity for two screens) 202A and 202B as described above. First, as shown in FIG.
The (first screen) is used for display, that is, for reading out image data, and the frame memory 202B (second screen) is used for writing image data transferred from the copier body 100 by the DMAC 102. Used for loading (for buffer).

As shown in FIG.
Therefore, the image data in the window unit which has been DMA-transferred is overwritten by the LCDC 201 by the window display range on the already written display data. When the writing is completed, the LCDC 201 uses the frame memory 202A (first memory) as shown in FIG.
Screen) and the frame memory 202B (second screen). That is, the frame memory 202A
The (first screen) is used for writing (buffer) data to be DMA-transferred, and the frame memory 202B (second screen) is used for display reading (for display). As a result, DM
The writing process by A is not displayed, and a window can be displayed on the LCD 300 in an instant.

FIG. 3 is a diagram showing a specific configuration example of the operation display unit 200 in FIG. LCDC201 is DMAC
DMA command analysis unit 21 for reading and analyzing the first command portion of data DMA-transferred from 102
0, a write address control unit 211 for writing data to the frame memory 202 (frame memory 202A, 202B), and the frame memories 202A, 20
2B, a selector 212 for selecting the color of the read image data, a color pallet 213 for specifying the color of the read image data, a gradation control unit 214 for adjusting the gradation to the specified color, and converting the image data into the format of the LCD 300 and transmitting the image data to the LCD 300 A format conversion unit 215 for transferring is provided.

FIG. 4 shows an example of a format of data transferred from the DMAC 202 of FIG. The data format shown in FIG. 4 includes a command, a write start X address, a write start Y address, a length in the X direction, the number of transfer bytes, display data 0 to N, and check data.

Next, the LCD 30 of the LCDC 201 will be described.
The operation of transferring data to 0 will be described. In FIG. 3, first, the DMA command analysis unit 210 reads the first command portion of the data (data of the format shown in FIG. 4) transferred from the DMAC 102, and when it is determined that the data is the write data, the successively transferred X Direction, Y
The write start address in the direction and the write length in the X direction are read. Next, the write address control unit 211 refers to this header portion and refers to the frame memory 202B.
The display data is written in the writing window area of the (second screen). Then, the write address control unit 211 checks whether or not there is no error in the contents of the DMA transfer in the last check data of the DMA. During this time, display data is read from the frame memory 202A (first screen) via the selector 212, and
13, the color is designated. Then, after gradation control is performed on a frame basis by the gradation control unit 214, the format conversion unit 215 converts the format into a format specific to the display medium of the LCD 300 such as STN or TFT, and transfers the format to the LCD 300 for display. Do.

As described above, the frame memory 202A (first screen) and the frame memory 202B (second screen)
Screen), the frame memory 202A (first screen) is used for writing DMA transfer data (for buffer),
The same operation is performed using the frame memory 202B (second screen) for display reading (for display).

As described above, in the first embodiment, the VRAM 10 is
3, the image data to be displayed on the LCD 300 is drawn,
The MAC 102 transfers the image data drawn in the VRAM 103 to the operation display unit 200 in units of windows for drawing, and the LCDC 201
One of the frame memories 202B (the second screen) is used as a buffer (for writing) and the image data transferred from the DMAC 102 is overwritten.
02A (first screen) for display, the frame memory 2
Since the image data written in 02A (first screen) is read and displayed on the LCD 300, the roles of the frame memory 202A (first screen) and the frame memory 202B (second screen) are switched. The data transfer amount can be reduced, and a new window can be displayed on the LCD 300 instantaneously without displaying the drawing process of the data being transferred to the frame memory.

(Embodiment 2) Embodiment 2 will be described with reference to FIGS. As described in the first embodiment, in the case of the transfer method for rewriting the entire screen,
As described above, there is no problem simply by switching between the two frame memories. However, when only a part of the screen is rewritten, the new data is reflected in the frame memory switched from read (for display) to write. It has not been.
Therefore, if new data is continuously overwritten, data will be lost.

In order to prevent this, in the second embodiment, as shown in FIG. 5, from writing to reading (display).
The data of the frame memory 202B switched to
New data is reflected by transferring the data to the frame memory 202A switched from read (display) to write.

FIG. 6 is a diagram showing a specific configuration example of the operation display unit according to the second embodiment. The schematic configuration of the copying machine according to the second embodiment is the same as that of the first embodiment (FIG. 1), and a description thereof will be omitted. The operation display unit shown in FIG. 6 is obtained by adding a DMA transfer unit 220 to the operation display unit shown in FIG. 3 (Embodiment 1). 6, the same parts as those in FIG. 3 are denoted by the same reference numerals, and the description of the same parts will be omitted. FIG.
In FIG. 3, for simplification of the description, the DM shown in FIG.
A command analyzer 210 and write address controller 211
Are not shown. The DMA transfer unit 220 transfers the image data of the frame memory on the reading side (for display) to the frame memory on the writing side (for writing) and also to the VRAM 103 of the copying machine body. It is.

In FIG. 6, after the frame memory 202B is switched to the reading side (for display), data is transferred from the frame memory 202B to the writing side frame memory 202A and overwritten. In the opposite case (frame memory 2
02A is the reading side), the frame memory 202A transfers the frame
To overwrite. Also, the frame memory 202B
Is transferred from the frame memory 202A (or from the frame memory 202A to the frame memory 202B) to the copier 100 at the same time as the
Overwrite M103. As a result, the copying machine body 100
The side can always keep the latest display data. That is, on the copying machine main body 100 side, the VRAM 10
3 is drawn in window units, but is data returned from the operation display unit 200,
The entire image of the image data displayed on the CD 300 can be known.

As described above, in the second embodiment, the contents of the frame memory on the display side are stored in the frame memory on the writing side and the VRAM 103 of the copier main body 100.
And overwrites it with the
The VRAM 103 of 0 and the frame memory on the writing side of the operation display unit 200 can always hold the latest image data displayed on the LCD 300, and it is easy to rewrite part of the data on the screen.

(Embodiment 3) Embodiment 3 will be described with reference to FIGS.
This will be described with reference to FIG. By the way, usually, a VRAM for color display often holds color information using a plurality of planes as shown in FIG. For example, when a 16-bit DRAM is used, as shown in FIG.
The 16 bits correspond to pixels 0 to 15, so that 16 pixels can be read by one DRAM access. If four 16-bit width DRAMs are arranged to form four planes, it is possible to configure so that four colors of data corresponding to the same position represent 16 colors.

The advantage of this method is that, when direct drawing is performed by the CPU, the number of access pixels per operation can be increased (16 pixels in the above example), so that high-speed drawing is possible even in the case of color display. Become. However, although this method is advantageous at the time of drawing, when DMA transfer is performed,
Since the bus width is widened, there is a problem that the number of connection harnesses increases when transferring to the operation display unit, and the configuration becomes large.

Therefore, in the third embodiment, the copying machine main body 1
When data is transferred from 00 to the operation display unit 200, the data stored in the memory is converted into a bus width and transferred.
Data transfer is possible with a simple configuration.

FIG. 9 is a diagram showing a schematic configuration of a display system of the copying machine main body according to the third embodiment. The configuration of the operation display unit 200 is the same as that of the first embodiment (FIG. 1). As shown in FIG. 9, the display system of the copying machine main body 100 includes a main CPU 101 for controlling each part of the copying machine, and DRAMs 111 to 111.
Batch writing of image data to be displayed on LCD 300 to DRAM 114 and DMA to operation display unit 200
Memory I / F & DMAC 110 for performing transfer, and four DRAMs 111 to DR for storing image data
AM114. DRAMs 111 to DRA
M114 corresponds to planes 1 to 4, respectively.

FIG. 10 is a diagram showing a schematic configuration of the interface unit of the memory I / F & DMAC 110. The interface unit of the memory I / F & DMAC 110 controls individual writing, batch writing, and the like for the four DRAMs 111 to 114. Specifically, the interface unit uses the selector 130 to select each of the planes 1 to 4 (the DRAM 11
1 to 114) to select the four DRAMs 111 to 11
4 are individually written.

FIG. 11 shows a memory I / F & DMAC 110
3 is a diagram showing a schematic configuration of a DMAC unit of FIG. As shown in the figure, the DMAC unit of the memory I / F & DMAC 110 includes a latch unit 120, a two-pixel packing unit 121, and an 8-bit serialization unit 122. In the DMAC unit, D
After the data read from the RAMs 111 to 114 is corrected to a bus width of 8 bits, the data is transferred to the operation display unit 200.
Specifically, in the latch unit 120, each of the DRAMs 111 to 111
The 16-bit data 114 is latched and output as 64-bit data, and the 2-pixel packing unit 121 packs the data of 2 pixels (1 pixel: 4 bits) and transfers the data to the 8-bit serializing unit 122, where As shown in FIG. 12, the serialization unit 122 converts the data of one pixel of 4 bits into the operation display unit 20 in units of 8 bits for two pixels.
DMA transfer to 0. In response, the operation display unit 200
Then, data is stored in the frame memory 202.

As described above, according to the third embodiment, individual writing to the four DRAMs 111 to 114 is performed collectively, and when DMA transfer is performed to the operation display unit, the data is stored in the four DRAMs 111 to 114. The transferred data is transferred after being corrected to an 8-bit bus width, so that the bus width of the bus used in the DMA transfer can be reduced. Can be easily performed.

It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately modified without changing the gist of the invention.

[0040]

As described above, according to the first aspect of the present invention, on the apparatus main body side, the data drawing means includes the first data drawing means.
The image data to be displayed on the display device is drawn in the storage means, and the data transfer means transfers the image data drawn in the first storage means to the display device side by window, and accordingly, the display device side Then, the writing means writes the image data transferred from the data transfer means using one frame memory of the second storage means having at least two frame memories for writing, and Since the other frame memory of the storage means is used for display, the image data stored in the other frame memory is read out and displayed on the display unit, and the switching means switches the role of at least two frame memories. Thus, the amount of data transfer can be reduced, and high-speed display can be performed.

According to a second aspect of the present invention, in the first aspect of the present invention, in the display device, the image data stored in the frame memory switched for display by the inter-memory data transfer means. Is transferred to the frame memory switched for writing. Therefore, in addition to the effect of the invention described in claim 1, the frame memory for writing is always the latest image displayed on the display unit. Data can be retained.

According to a third aspect of the present invention, in the display device according to the second aspect, the display device converts the image data stored in the frame memory switched for display by the reverse transfer means. Since the data is transferred to the first storage means of the apparatus main body, in addition to the effect of the invention described in claim 2, the first storage means of the apparatus main body side always stores the latest image displayed on the display unit. Data can be retained,
It becomes easy to rewrite part of the data on the screen.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the data drawing means stores the image data in the first storage means in a simultaneous multi-bit manner. Writing is performed, and the data transfer unit reads out the image data drawn in the first storage unit, converts the data into the data width of the transfer bus, and transfers the data to the display device side. The bus width of the bus can be reduced.

According to the fifth aspect of the present invention, the image data to be displayed on the display device is drawn in the first storage means provided in the apparatus main body, and the image data is drawn in the first storage means. The image data is transferred from the device body to the display device side, the image data transferred from the device body side is written as one of the at least two frame memories for writing, and the other frame memory is used for display, Since the image data stored in the other frame memory is read out and displayed on the display unit, and the roles of at least two frame memories are switched, the data transfer amount can be reduced, and the high-speed display can be performed. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration example of a display system of a copying machine in a first embodiment.

FIG. 2 is an explanatory diagram for explaining data transfer of a DMAC of the copying machine main body of FIG. 1;

FIG. 3 is a diagram showing a specific configuration example of an operation display unit in FIG. 1;

FIG. 4 is a diagram illustrating an example of a format of data transferred from a DMAC in FIG. 1;

FIG. 5 is an explanatory diagram for describing data transfer between frame memories in a second embodiment.

FIG. 6 is a diagram showing a specific configuration example of an operation display unit in the second embodiment.

FIG. 7 shows a VRA for color display in the third embodiment.
It is a figure showing a plurality of planes of M.

FIG. 8 is a diagram for describing the number of read pixels of the VRAM of FIG. 7 in the third embodiment.

FIG. 9 is a diagram illustrating a schematic configuration example of a display system of a copying machine main body according to a third embodiment.

10 is a diagram illustrating a schematic configuration example of an interface unit of a memory I / F & DMAC in FIG. 9;

FIG. 11 shows a memory I / F of FIG. 9 in the third embodiment.
FIG. 3 is a diagram illustrating a schematic configuration example of a DMAC unit of & DMAC.

FIG. 12 is an explanatory diagram for describing a unit of data to be DMA-transferred in a third embodiment.

FIG. 13 is a diagram for explaining a conventional technique relating to an interface between a copier main body and an operation display unit using an LCD or the like.

FIG. 14 is a diagram for explaining a conventional technique relating to an interface between a copying machine main body and an operation display unit using an LCD or the like.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 copier main body 101 main CPU 102 DMAC (DMA controller) 103 VRAM 104 bus 110 I / F & DMAC 111 to 114 DRAM 200 operation display unit 201 LCDC (liquid crystal display controller) 202 frame memory 210 DMA command analysis unit 211 write address control unit 212 Selector 213 Color palette 214 Gradation control unit 215 Format conversion unit 220 DMA transfer unit 300 LCD

Claims (5)

[Claims] 1. A display control device for transferring image data from a device main body to a display device for display, wherein the device main body includes: first storage means for storing image data; and first storage means. Data drawing means for drawing image data to be displayed on the display device, and data transfer means for transferring the image data drawn in the first storage means to the display device side in window units, A display unit for displaying image data; a second storage unit having at least two frame memories; and a frame memory of one of the second storage units for writing, the data being transmitted from the data transfer unit. Writing means for writing image data to be transferred; and image data stored in the other frame memory of the second storage means for display. A display control device comprising: reading means for reading data and displaying the data on the display unit; and switching means for switching roles of the at least two frame memories. 2. The display device according to claim 1, wherein the switching unit transfers the image data stored in the frame memory switched for display to the frame memory switched for writing. The display control device according to claim 1, further comprising a data transfer unit. 3. The reverse transfer means for transferring the image data stored in the frame memory switched for display by the switching means to the first storage means of the apparatus main body. The display control device according to claim 2, further comprising: 4. The first storage means is provided so as to allow simultaneous multi-bit access, and the data drawing means performs simultaneous multi-bit writing of image data to the first storage means, 4. The transfer unit according to claim 1, wherein the transfer unit reads out the image data drawn in the first storage unit, converts the image data into a data width of a transfer bus, and transfers the data to a display device. The display control device according to one of the above. 5. A data transfer method for transferring image data from a device main body to a display device to a display device for performing display, wherein the first storage means provided in the device main body includes: Drawing image data to be displayed; transferring the image data drawn in the first storage means from the device main body to the display device; writing one of the at least two frame memories Writing image data transferred from the apparatus body side for use; reading the image data stored in the other frame memory for display on the other frame memory for display on the other frame memory for display; Switching a role of two frame memories; and a method of transferring data to a display device.