JPH08183208A - Method and apparatus for recording bit map - Google Patents

Abstract

PURPOSE: To provide a method for recording a bit map which requires only a smaller memory capacity for storing mask patterns and an apparatus for the method. CONSTITUTION: A bit map in a development buffer 302 is transferred for every recording path to a recording data buffer 303 through an AND circuit 102, and the logical product of the bit map in the development buffer 302 and a bit map inverted by an inversion circuit 109 is taken by an AND circuit 110 to renew the bit map in the development buffer 302 through an unrecorded data buffer 111. In other words, the bit map in the development buffer 302 is transferred for every recording path to the recording data buffer 303 through the AND circuit 102, and the bit map in the development buffer 302 is renewed through the AND circuit 110 and the unrecorded data buffer 111 so that the number of mask patterns to be prepared is made smaller by one than that of the recording paths.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bitmap recording method and recording apparatus, and more particularly to a bitmap recording method and recording apparatus for recording a bitmap by a plurality of recording passes according to a predetermined recording method.

[0002]

2. Description of the Related Art Conventionally, in dot printers such as ink jet printers, there is known a technique of printing data by dividing it into a plurality of passes (thinning-out recording) in order to obtain a high-quality recording result with less ink bleeding. .

For example, when a character "A" such as the bit map (8 × 8) of reference numeral 406 in FIG. 4 is recorded, four mask patterns for thinning recording such as reference numerals 402 to 405 are prepared, and these mask patterns are prepared. And the bitmap of the code 406 (“&” in the figure indicates the logical product of the bitmaps of the codes) to obtain the bitmaps 407 to 410 and the bitmaps 407 to 410. Is sequentially input to the recording head to record the character "A".

In the mask patterns 402 to 405, one of the 8 × 8 dots is an effective dot (illustrated by a black dot) only once in the four mask patterns, and is adjacent to each other simultaneously in one pass printing. Care is taken not to record dots. In the logical product operation, only the dots that are black dots remain as black dots in both of the two bitmaps that are logically ANDed (for example, bitmaps 406, 403, and 408).
See the 1 dot in the lower right corner of.

A printer that performs such a printing operation is
It is configured as shown in FIG. That is, the host 300
The data sent from the device via the SCSI interface, the Centronics interface, the network, etc. is temporarily stored in the input buffer 301.

The data transferred from the host 300 is composed of image data, character code, etc., and is described in a predetermined printer language or page description language in some cases. In the case of character code, etc., it is stored in a ROM or the like. The stored font data is used to develop an image into a bitmap corresponding to the resolution of the printer head, and the image is taken into the expansion buffer 302.

After that, the mask processing described above, or if necessary, variable magnification, smoothing processing, and other image processing, is carried out, and the result is taken into the recording buffer 303. The data in the recording buffer 303 is sequentially transferred to the recording head 304 and recorded according to a predetermined recording method.

FIG. 5 shows an example of a configuration for performing the above-mentioned mask processing between the expansion buffer 302 and the recording buffer 303. In FIG. 5, an AND circuit 502 is provided between the expansion buffer 302 and the recording buffer 303.
The mask patterns 402 to 405 (the same as those in FIG. 4) written in the mask buffer 508 by the ND circuit 502 are ANDed with the bitmap read from the expansion buffer 302.

In the first pass of 4-pass printing, after the mask pattern 402 is written in the mask buffer 508,
Dots at the same position are read one by one from the expansion buffer 501 and the mask buffer 508, and the AND circuit 50
2 and the output of the AND circuit 502 is written in the same position of the recording buffer 303.

Similarly, in the second and subsequent passes of the 4-pass printing, the mask patterns 403, 404 and 405 are sequentially used, the data 408, 409 and 410 of FIG. 4 are respectively generated and written in the print buffer 303. .

[0011]

However, in the conventional example as described above, when printing a plurality of passes, it is necessary to store the same number of mask patterns as the number of passes in the memory. However, there is a problem that the cost increases due to the increase of

For example, recently, due to a trade-off between required recording quality and throughput, for example, 2 passes and 4 passes are performed.
There are printers that can select paths, but in this case, six types of mask patterns must be stored in the memory.

An object of the present invention is to solve the above problems, and to provide a bitmap recording method and a recording apparatus which require a small memory capacity for storing a mask pattern.

[0014]

In order to solve the above problems, in the present invention, when a bitmap is recorded by a plurality of recording passes by a predetermined recording method, the bit to be recorded stored in the expansion buffer is to be recorded. When a bitmap to be recorded in each recording pass is generated by taking the logical product of the map and a predetermined mask pattern, the logical product of the bitmap to be recorded and the mask pattern stored in the expansion buffer is calculated. The logical product process, the bit map in which the logic of the mask pattern is inverted, and the second logical product process that takes the logical product of the bitmaps to be recorded stored in the expansion buffer are included, and each recording pass The bitmap in the expansion buffer should be transferred to the recording mechanism via the first AND operation and recorded in the expansion buffer via the second AND operation. It adopted a structure in which to update the bitmaps.

[0015]

With the above arrangement, since the unrecorded portion of the expansion buffer is updated by the read modify write for each recording pass, the number of mask patterns to be prepared should be one less than the number of passes. Can be reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. In the following, the same or corresponding members as those in the conventional example will be denoted by the same reference numerals, and detailed description thereof will be omitted.

FIGS. 1 and 2 correspond to FIGS. 5 and 4 of the conventional example, respectively. The structure for performing mask processing between the expansion buffer 302 and the recording buffer 303, and the bits used in mask recording. Shows the map.
The overall configuration of the device is the same as in FIG.

1 is different from the conventional one in that
In addition to the AND circuit 102 corresponding to the ND circuit 502, A
That is, the ND circuit 110 is provided.

The AND circuit 110 is an AND circuit 10.
2 is the result of inverting the logic of the output of the mask buffer 508 input by the inversion circuit 109 and the expansion buffer 3
AND of the pixel data read from 02 (the same as that input to the AND circuit 102).
The output of the circuit 110 is written in the same position as the recording buffer 303 of the unrecorded buffer 111.

The mask patterns 202 to 204, 211, etc. are usually placed in a memory space such as a RAM and the AND circuit 1
02, recording buffer 303, mask buffer 508, inverting circuit 109, AND circuit 110, unrecorded buffer 11
1 is usually constructed on a control circuit such as a GA.

The mask patterns 202 to 203 are
As shown in FIG. 2, the mask patterns 402 to 40 of FIG.
It is the same as 3. These mask patterns 202-2
03 is for 4-pass printing. In the present invention, only three types of mask patterns 202 to 203 are required for four-pass printing as described later.

2 shows the mask pattern 205 (the same as the mask pattern 405 in FIG. 4) for convenience, this mask pattern 205 is unnecessary in the present invention, as will be described later, and FIG. , The mask pattern 211 is shown, but this mask pattern 211 is for two-pass printing. In the present invention, one type of mask pattern 211 is used for two-pass printing as described later.
I only need it.

The operation of the above configuration will be described below. Here, as in the conventional example, consider the case where the character "A" is printed in four passes.

In the above structure, the operation of the AND circuit 102 is the same as that of the conventional AND circuit 502, and the dots at the same position are read from the expansion buffer 302 and the mask buffer 508 one by one and input to the AND circuit 102. The output of the AND circuit 102 is written in the same position in the recording buffer 303.

That is, by the operation of the AND circuit 102, the mask pattern 20 is generated in the first pass of the 4-pass printing.
2 is read into the mask buffer 508, and the bit map 407 is formed from the logical product of the mask pattern 202 and the bit map 206 (character “A”),
This bitmap 407 is written in the recording buffer 303.

At the same time, one dot at the same position is read out from the expansion buffer 302 and the mask buffer 508 one by one, and the output of the mask buffer 508 is inverted.
Input to the upper AND circuit 110 which is inverted by 09,
The logical product of these is taken.

The inverting circuit 109 allows the mask buffer 5
A black and white inversion of the pattern in 08 (mask pattern 202 of FIG. 2 in the first pass) is obtained. That is, all the bits that were not recorded due to the pattern in the mask buffer 508 in that pass are inverted.

The bit map 206 of the inverted mask pattern and the bit map 206 of the character "A" are AND circuit 1
Taken at 10. In the case of the first mask pattern 202, the bitmap 207 of FIG. 2 is obtained. As shown, the bitmap 207 has white dots in the mask pattern 202, and the bitmap 206
Only the pixels that are black dots are black dots.

The bit map obtained by the AND circuit 110 is written in the same position in the unrecorded buffer 111 in synchronization with the writing from the AND circuit 102 to the recording buffer 303.

Then, the contents of the unrecorded buffer 111 are
By the read modify write, the expansion buffer 302
2 and the contents of the expansion buffer 302 are written to
It is changed to 07 data. This read-modify-write may be performed after processing one bit map (8 × 8 dots in this embodiment), or after the first reading from the expansion buffer 302 to the AND circuits 102 and 110. For example, it may be performed in bit units.

That is, in the present embodiment, the expansion buffer 30
The contents of 2 are not the same in each pass, and are sequentially changed via the AND circuit 110 and the unrecorded buffer 111. As is clear from the comparison between the bitmaps 206 and 207 of the first pass, this modification of the contents of the expansion buffer 302 may be considered as a process of removing the black dots already recorded in that pass from the expansion buffer 302.

Then, each time the bitmap for one pass is prepared in the print buffer 303, the contents of the print buffer 303 are printed by the print head as in the conventional case.

By the same operation, when the second pass operation is performed, in the second pass, the bitmap 408 is written in the recording buffer 303 as usual, and the expansion buffer 302 is passed through the AND circuit 110 and the unrecorded buffer 111. 2 is changed to the bitmap 208 of FIG.

Further, when the operation of the third pass is performed, in the third pass, the bitmap 409 is written in the recording buffer 303 as usual, and the expansion buffer 302 is also used.
2 is changed to the bitmap 209 in FIG.

Here, comparing the bitmap 209 and the bitmap 410 (FIG. 4) generated in the fourth pass of the conventional example, it can be seen that they are the same. Therefore, by inputting the contents of the expansion buffer 302 into the recording buffer 303 without passing through the processing of the AND circuit 102, the same fourth pass bitmap as in the conventional case can be generated. Therefore, the bitmap 205 becomes unnecessary as mentioned above, and it is not necessary to prepare it in the memory.

In the four passes, the expansion buffer 30
Inputting the contents of No. 2 into the recording buffer 303 without passing through the processing of the AND circuit 102 is performed by an AN via a route not shown.
This can be done by bypassing the D circuit 102 or by pulling up the signal line from the mask buffer 508 to the AND circuit 102 to an active logic level by a switch (not shown).

As described above, according to this embodiment, since the unrecorded portion is updated by the read-modify-write after the bitmap of the expansion buffer is read, the mask pattern to be prepared is passed. 1 more than a number
The number can be reduced to a smaller number, the data memory capacity can be reduced, and the cost can be reduced.

In the above, 4-pass printing was considered, but in the case of 2-pass printing, data can be generated with only one mask pattern. That is, as I mentioned earlier, 4
When preparing one mask pattern, three of them are 4
One for the pass recording and the other one (211 in FIG. 1) for the two-pass recording. Conventionally, six types were required to perform both the two-pass and the four-pass recording. The storage area for the mask pattern can be greatly reduced.

The selection of 2-pass and 4-pass recording is as follows.
It can be performed according to a designated operation such as high-speed recording or fine recording.

In the above, the recording of characters has been taken as an example, but it goes without saying that the same technique can be implemented when an image is printed as a bitmap unit of a predetermined size.

[0041]

As is apparent from the above, according to the present invention, the bitmap in the expansion buffer is recorded through the first logical product process and the second logical product process is performed for each recording pass. The configuration is such that the bitmap in the expansion buffer is updated via, and the unrecorded part of the expansion buffer is updated by read-modify-write for each recording pass. It is possible to reduce the number of patterns to one less than the number of print passes, and there is an excellent effect that the memory capacity required for storing the mask pattern is small.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of a recording apparatus adopting the present invention.

FIG. 2 is an explanatory diagram showing a processing state of a mask pattern and a bitmap used in the present invention.

FIG. 3 is a block diagram of a recording device.

FIG. 4 is an explanatory diagram showing a state of processing of a mask pattern and a bitmap used in a conventional technique.

FIG. 5 is a block diagram of a main part of a conventional recording apparatus.

[Explanation of symbols]

 102 AND circuit 109 Inversion circuit 110 AND circuit 111 Unrecorded buffer 302 Expansion buffer 303 Recording buffer 402 Mask pattern 403 Mask pattern 404 Mask pattern 405 Mask pattern 501 Expansion buffer 508 Mask buffer

Claims (8)

[Claims] 1. When a bitmap is recorded by a plurality of recording passes by a predetermined recording method, a logical product of a bitmap to be recorded stored in an expansion buffer and a predetermined mask pattern is used to obtain a logical product in each recording pass. In a bitmap recording method for generating a bitmap to be recorded, a first logical product step of obtaining a logical product of the bitmap to be recorded stored in the expansion buffer and the mask pattern, and the first logical product step A step of sending the bitmap obtained by the above to a recording mechanism; a second logical AND step of taking the logical product of the bitmap in which the logic of the mask pattern is inverted and the bitmap to be recorded stored in the expansion buffer And the bit map obtained by the second AND step, the record stored in the expansion buffer is recorded. For each recording pass, the bitmap in the expansion buffer is transferred to the recording mechanism via the first AND operation step, and the second AND operation step is performed. A bitmap recording method, characterized in that a bitmap to be recorded in the expansion buffer is updated. 2. The bitmap recording method according to claim 1, wherein the bitmap in the expansion buffer is output by a predetermined output method. 3. The bitmap recording method according to claim 2, wherein the bitmap is output by an inkjet recording method. 4. The bitmap recording method according to claim 1, wherein recording data in a predetermined format is input from a host computer, and a bitmap to be recorded based on this recording data is expanded in a expansion buffer. 5. When a bitmap is recorded by a plurality of recording passes by a predetermined recording method, a logical product of the bitmap to be recorded stored in the expansion buffer and a predetermined mask pattern stored in the mask buffer. A recording device for generating a bitmap to be recorded in each recording pass by taking a logical AND of a bitmap in the expansion buffer and a mask pattern in the mask buffer; A recording data buffer for sending the output of the AND means to the recording mechanism, an inverting means for inverting the logic of the mask pattern in the mask buffer, a bitmap in the expansion buffer and a bitmap inverted by the inverting means. A read-modify operation is performed by the second AND means for taking a logical product and the output of the second AND means. And an unrecorded data buffer for updating the bitmap in the expansion buffer by means of a write operation and transferring the bitmap in the expansion buffer to the recording data buffer via the first AND means for each recording pass. , A recording device for updating the bit map in the expansion buffer via the second AND means and the unrecorded data buffer. 6. The recording apparatus according to claim 5, further comprising an output unit that outputs the bitmap in the expansion buffer by a predetermined output method. 7. The recording apparatus according to claim 6, wherein the output unit outputs the bitmap by an inkjet recording method. 8. The recording apparatus according to claim 5, further comprising a host computer for inputting recording data of a predetermined format which is a basis of a bitmap to be recorded.