JP2730507B2 - Printer device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer, and more particularly, to direct memory access (DMA) transfer of video data from a rendering area to a video interface unit.
It relates to a printer device called a page printer.

[0002]

2. Description of the Related Art Heretofore, there has been a printer apparatus which develops data rendered by a character code, an image, and a figure in a rendering area (frame buffer or band buffer) and DMA-transfers the video data to a video interface unit. Known (for example, Japanese Patent Application Laid-Open No.
No. 3).

FIG. 3 is a block diagram showing an example of the conventional printer. This printer device includes a host computer 1 for sending out text data, image data and control data, an interface unit 2 for receiving output data of the host computer 1, a program ROM 3 in which a print processing control program is stored, and font data stored in advance. Font ROM4, program RO
A central processing unit (CPU) 5 which operates in accordance with the program of M3 and generates text data and image data for printing, a text buffer 6, a video band buffer (VBB) 7, an overrun error detection section 8
a, a VBB area changing means 8b, a parallel / serial (P / S) conversion section 9, and a printing section 10.

[0004] A text buffer 6 stores text data from the host computer 1. The VBB 7 has a random access memory (RA) together with the text buffer 6.
M), and stores each text data created on the text buffer 6 as an actual print image image. In this conventional printer, the text data in the text buffer 6 is stored while being converted into an image image to be actually printed on the VBB 7, and the image data of the VBB 7 is transferred to the video interface P / P by DMA transfer. The data is transferred to the S conversion unit 9, where it is subjected to parallel-serial conversion, and then serially supplied to a printing unit (engine) 10 for printing.

At this time, the expansion processing is delayed, and the P / S converter 9
If the DMA transfer cannot be performed in time for the video data transfer in the above, character omission occurs. In the conventional device, when the overrun error is detected by the detection unit 8a, the area occupied by the VBB 7 is increased by the VBB area changing means 8b, and the initial development amount is reduced. In addition, normal printing can be performed in reprinting.

[0006]

However, in the above-described conventional printer, when the development of the image-processed data in the development area is delayed, the P / S converter 9 cannot transfer the video data in time for the DMA transfer. First, there is a problem that data before one cycle or more is sent to the printing unit 10 (printer engine), and characters are omitted or different data is printed.

[0007] The present invention has been made in view of the above points,
It is an object of the present invention to provide a printer device capable of correcting a character omission by detecting a character omission occurring at a high printing speed by hardware.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a memory for storing video data to be printed, which has been subjected to a development process, in a drawing development unit, and direct memory access of the video data in the memory in word units. Controller for transferring, direct memory access video interface for parallel / serial conversion of transferred video data, printer engine for printing video data from video interface, and acknowledge signal from controller and output video data of memory based on ,
A miss-character recognition circuit provided in the video interface, which compares the number of times of direct memory access transfer with the number of times of printing in words and generates an interrupt when the number of times of transfer is smaller than the number of times of printing to output display data; It has a configuration having a display unit for displaying display data.

[0009]

According to the present invention, the number of direct memory access transfers to the video interface of video data is compared with the number of video data transfers to the printer engine in word units, and the number of direct memory access transfers to the printer engine is monitored. Since the display data is generated by the character recognition circuit and displayed on the display unit when the number of times, that is, the number of times of printing is not enough, the user can be notified of the character omission due to the delay of the drawing development process and the printing of different data.

[0010]

Next, an embodiment of the present invention will be described. FIG. 1 is a block diagram showing an embodiment of a printer according to the present invention. As shown in FIG.
1a, a memory controller 11, a DMA controller 12, a video interface 13, a printer engine 14 as a printing unit, and an operator panel 15.

The rendering unit 11a is a frame buffer or a video band buffer (VBB) storing binary data (video data) subjected to rendering processing to be printed.
It is. The DMA controller 12 transmits the video data stored in the rendering unit 11a to the video interface 1
3 is DMA-transferred.

The video interface 13 includes a unit data transfer end recognition unit 21, a comparison counter 22 that outputs a count value indicating a result of comparison between the number of times of direct memory access transfer and the number of times of printing in word units, and a count value of the comparison counter 22. Has a character omission recognition circuit 20 including a circuit section (not shown) for generating display data when is less than a predetermined value.
The printer engine 14 prints video data from the video interface 13. The operator panel 15
The display data such as the character omission output from the character omission recognition circuit 20 is displayed.

Next, the operation of this embodiment will be described with reference to the time chart of FIG. Video data input from the outside is stored in a rendering unit 11 a in the memory 11. When the DMA acknowledge signal a shown in FIG. 2A is activated by the DMA controller 12, the video data is DMA-transferred from the rendering unit 11 a to the video interface 13.
Here, after the parallel-serial conversion, it is printed by the printer engine 14 as shown by c in FIG.

Each time the data transfer of video data to the printer engine 14 is completed in word units, the unit data transfer end recognition unit 21 generates a word transfer end pulse b as shown in FIG. 2B. Input to the comparison counter 22. The comparison counter 22 receives the word transfer end pulse “b” and the DMA acknowledge signal “a” from the DMA controller 12 as input signals, and is incremented by “1” every time the DMA acknowledge signal “a” is input. "1" every time is input
Decrement. FIG. 2D shows this comparison counter 22.
Is shown.

Therefore, assuming that the initial value of the comparison counter 22 is "0", the serial video data transfer to the printer engine 14 for the word unit DMA transfer is not performed for normal printing. Since printing is performed the number of times, it is "0" at the end of printing. However, when the expansion process is delayed and the DMA transfer cannot be performed in time for the video data transfer in the video interface 13, the count value of the comparison counter 22 becomes “0” or less. In this case, the character recognition circuit 20 generates an interrupt, and the operator panel 15
Outputs display data to indicate that a spelling has occurred.

That is, in this embodiment, the expansion processing is delayed,
When the DMA transfer cannot be performed in time for the video data transfer in the video interface 13, the video interface 13 cannot output the video data to be printed because there is no data to be transferred, and as a result, the printing result is missing dots. However, since the user can know the missing dots (missing characters) by the display on the operator panel 15 as described above, the same printing can be performed again when the load on the CPU is reduced.

[0017]

As described above, according to the present invention,
When the number of times of direct memory access transfer of video data to the video interface is not sufficient for the number of times of printing, display data is generated by the character recognition circuit and displayed on the display unit, so that the user may be able to obtain character omission due to a delay in drawing development processing. Since the printing of different data is notified, it is possible to correct by printing again without missing characters or missing the printing of different data.

[Brief description of the drawings]

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

FIG. 2 is a time chart for explaining the operation of FIG. 1;

FIG. 3 is a configuration diagram of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Memory 11a Drawing development part 12 Direct memory access (DMA) controller 13 Video interface 14 Printer engine 15 Operator panel 20 Omission recognition circuit 21 Unit data transfer end recognition part 22 Comparison counter

Claims (2)

(57) [Claims] 1. A memory for storing expanded video data to be printed in a rendering unit, a controller for performing direct memory access transfer of video data in the memory in word units, and the direct memory access transferred video A video interface for parallel / serial conversion of data, a printer engine for printing video data from the video interface, a direct memory access transfer count and word unit based on an acknowledge signal from the controller and output video data of the memory Comparing the number of print executions, and generating an interrupt when the number of transfers is smaller than the number of print executions to output display data; a character recognition circuit provided in the video interface; and displaying the display data. Display unit Printer and wherein the. 2. A unit data transfer end recognizing unit for generating a word transfer end pulse each time the video data transferred from the video interface to the printer engine ends in word units, and the controller A counter which receives an acknowledgment signal and a word transfer end pulse from the unit data transfer end recognition unit as input signals, and outputs a count value indicating a result of comparison between the number of times of direct memory access transfer and the number of times of printing in word units. 2. The printer device according to claim 1, further comprising: a circuit unit for interrupting the display data when the count value of the comparison counter is equal to or smaller than a predetermined value.