JPS61199958A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To enable not only dither method recording, but also density pattern method recording, using a dither method recording circuit, by calling one line recording signals stored in a memory a plural number of times and by constituting them to enable comparison respectively with thresholds within a dither matrix. CONSTITUTION:The constitution is made up with the first signal producing circuit necessary to perform recording of a density pattern method; the second signal producing circuit necessary to perform recording of a dither method and a data selector 23 and a transfer switch 24 necessary for transferring of the density pattern recording and the dither recording. Within the constitution stated above, recording signals of one line stored in shift registers 3-6 are called a plural number of times with the uses of a clock pulse generator 12, a frequency divider 14, a line signal generator 13, a counter 15, a counter 17, a decoder 18, an inverter 19, AND gates 16-20, and etc. in accordance with the connection diagram herewith, and the comparison with respective thresholds in the dither matrix is made feasible.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an inkjet recording device, and in particular, to a halftone recording technique thereof, in which recording information is sent from the host side as recording information in pixel unit density. The present invention relates to an ink jet recording apparatus suitable for performing halftone recording using dots based on signals.

[Background of the invention]

In inkjet recording, halftone recording has conventionally been published in Journal of the Institute of Image Electronics Engineers, 1984, VOL.

The dither method and density pattern method as described in No. 13, Al are most commonly used.

In the dither method, each threshold value is arranged in a matrix, and one pixel information of the recording signal sent from the host is compared with the corresponding threshold value in the matrix, and the one pixel information of the recording signal is M) If it is larger (or smaller) than the threshold value in the IJ box, one dot is recorded on the recording medium.

That is, even if one pixel information of the recording signal input to the recording device has a large amount of information, in actual recording, one dot is recorded for each pixel, or one dot is recorded for each pixel.
The loss of this information is extremely large because it becomes a binary record of "or not".

Therefore, when used for something like a hard copy display, each pixel of the display has a maximum of 25 pixels.
Even if it has density information of 6, it is recorded as a binary image, so
This can result in a very grainy recording, or one that bears no resemblance to the image on the display, making it unusable.

On the other hand, the density pattern method is a method in which patterns with different numbers of recording dots are prepared and patterns in which the density of one pixel information of the recording signal sent from the host and the average density are the same are recorded.

When an 8×8 matrix pattern is created using this method, 64 gradations can be recorded. Therefore, when making a hard copy of the above-mentioned display, etc., there is less loss of density information, and good recording can be achieved.

By the way, when copying by connecting to a scanner configured using a photoelectric conversion element, the image reading area (pixel) can be kept very small, and even if the loss of information per pixel is large, , it is possible to capture a large number of pixels of information.

For such objects, recording using the density pattern method described above produces false contours resembling contour lines at the points of change in density, so conversely, recording using the dither method may produce better recording. It is something that becomes.

The recording information source is the above-mentioned display, scanner, etc., both of which are used frequently, and unlike the above, conventionally, it is necessary to have both a dither method recording circuit and a density pattern method recording circuit in the recording device. There was a problem.

[Purpose of the invention]

The present invention uses a dither method recording circuit without having both a dither method recording circuit and a density pattern method recording circuit, and enables only dither method recording and density pattern method recording, thereby simplifying the circuit. The object of the present invention is to provide an inkjet recording apparatus having an inexpensive halftone recording circuit.

[Summary of the invention]

The configuration of the inkjet recording apparatus according to the present invention includes a threshold generation circuit that generates a threshold value of a dither matrix;
comprising a storage means for storing a recording signal representing the density for each pixel, and a comparison circuit for comparing the threshold value and the recording signal, and dot recording based on the comparison result,
In an inkjet recording device that performs halftone expression, one line of the recording signal stored in the storage means for storing the recording signal is called out multiple times and each is compared with the threshold value in the dither matrix. It is something.

Further details are as follows.

The density pattern of the density pattern method is created based on the dither matrix of the dither method, and the density pattern method recording can be performed by comparing one pixel of the recording signal with all the threshold values in the dither matrix and recording.

Therefore, by storing the recording signal sent from a host such as a scanner or CRT in a line buffer, and comparing it with all the threshold values in the dither matrix and recording it, the density pattern method is possible. Although recording can be performed and stored in a line buffer, dithering recording can also be performed by individually comparing them with threshold values in a dither matrix.

[Embodiments of the invention]

Embodiments of the inkjet recording apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic block diagram of an inkjet recording apparatus according to an embodiment of the present invention, FIG. 2 is a waveform diagram showing main waveforms thereof, and FIG. 3 is an inkjet recording apparatus according to another embodiment. FIG. 4 is a flowchart of what is shown in FIG. 3.

First, what is shown in FIG. 1 is composed of the following items.

In other words, the buffer 2 transmits and receives signals to and from the host 1.
and shift registers 3 to 6 with a recycling function, which are line buffers that store recording signals representing density for each pixel, which is image information for one line related to one line.
ROM7 that stores the dither threshold and ROM7
counters 8 to 9 for sequentially reading out the threshold values stored in , and a comparator 10 associated with a comparison circuit to compare the threshold values with the image signals output from the shift registers 3 to 6; An amplifier 11 that amplifies the obtained signal to supply it to the inkjet nozzle, a first signal generation circuit necessary for density pattern recording, and a second signal generation circuit necessary for dither recording. , a data selector 23 and a changeover switch 24 for switching between density pattern recording and dither recording.

Thus, the first signal generation circuit 1 described above is a clock pulse generator 12. Line signal generator 139 frequency divider 14. Counter 15. AND gate 16. Counter 17. Decoder 18. It is composed of an inverter 19 and an AND gate 20, and the second signal generation circuit is composed of a tarok pulse generator 12, a line signal generator 13, a counter 21, and an AND gate 22. be.

Further, the ROM 7 and counters 8 and 9 constitute a threshold generation circuit that generates a threshold value for the dither matrix.

Further, the shift registers 3 to 6 are storage means for storing symbol signals representing the density for each pixel.

In this embodiment, the host 1 is set so that the image signal is sent pixel by pixel as a digital signal from the host 1 at the rising edge (or falling edge) of the transfer lock.

The data selector 23 selects between the density pattern method recording and the dither method recording depending on the state of the changeover switch 24.

Therefore, in the above configuration, the tarock pulse generator 129, the frequency divider 14, the line signal generator 13, the counter 1
5, counter 17, decoder 18, inverter 19, A
With the ND gates 16 and 20 connected as shown in the figure, one row of recording signals stored in the shift registers 3 to 6 is called out multiple times and each is compared with a threshold value in the dither matrix.

Next, as described above, FIG. 2 shows the main waveforms of this embodiment, and therefore, a to h in FIG. 1 will also be explained.

a is a clock pulse with the same frequency (or a fraction of an integer) as the ink droplet creation frequency of inkjet recording,
It is outputted by a tarok pulse generator 12.

b is a line signal that generates a low pulse at the beginning (or end) of each line, and is output from the line signal generator 13.

cH, the clock pulse a is frequency-divided by the frequency divider 14, and in the case of 16 gradations, the frequency is divided by 1/4.

d is set to 1 using the counter 15 and the AND gate 16.
This shows the clock pulses created for the number of pixels corresponding to one line.

If the number of pixels in one line of the display is 512, 512 clocks are created in one line as shown in the figure.

e is a transfer lock sent to the host 1, which is composed of a counter 17, a decoder 18, an inverter 19, and an AND gate 20, and in the case of 16 gradations, transfers 512 tallocks for 1 line out of 4 lines to the host 1. It is now sent to.

This is a signal that determines whether to recycle the data in the shift registers 3 to 6 of the f[, 512 pits, or input new data.It is set to input new data when it is LOW, and to recycle when it is HIGH. This is related to the output of the decoder 18.

Here, when the data selector 23 shown in FIG. 1 outputs signals d and f depending on the state of the changeover switch 24, density pattern recording is selected.

That is, since the frequency-divided clock pulse d is 1/4 of the ink droplet creation frequency (i.e., a),
It is enlarged 4 times in the horizontal direction (main scanning direction), and by the above f, which takes in a new recording signal at Low and outputs the recording signal at High, a total of 4 lines, including the case of Low, In order to output the same data, the vertical direction (
Since the magnification is 4 times in the sub-scanning direction), one pixel is 4 times
4 matrices are formed and compared with the entire threshold value in the dither matrix of the ROM 7, recording is performed using the density pattern method.

In other words, by calling the recorded signal of one line multiple times and adjusting the threshold value in the dither matrix,
Next, out of the clock pulses a that have the same frequency as the ink droplet creation frequency, tarock pulses equal to the number of pixels in one line are created, and the eight counters 21 and AND gates 22 Created by.

hH, shift registers 3 to 6 are always kept in a low state in order to always receive new data.

If the data selector 23 selects and outputs g and h, one pixel of image information corresponds to one matrix threshold value in R, 0M7, so dither recording is performed.

In this way, by using the device according to this embodiment, both density pattern recording and dither recording can be performed with one circuit.

In this embodiment, 16 gradations are shown, but by adding a shift register and a counter, the number of gradations can be easily changed to 32 gradations, 64 gradations, etc. .

FIG. 3 shows another embodiment.

In the figure, 11 is an amplifier as before, 25 is a microcomputer, 26 is a data/address bus, 27 is a work RAM 128fl program ROM, 29 is an input/output element, and 30 is a line buffer.

That is, the present embodiment is a modification of the previous embodiment using a microcomputer, and the microcomputer has a 25° work RAM 27.
Program ROM 28° input/output element 29. Line buffer 30 and data/address bus 26 connecting each
It is composed of

FIG. 4 shows a flowchart of the program in this configuration.

First, check whether you are using dither recording or density pattern recording.

If dither recording is used, one pixel (k pixel) of the image signal and the threshold values (j, i), (j-1 to
4. i=1 to 4) and record it.

In addition, in the density pattern method, one pixel (k
pixel) and all of the threshold values (j, i) in the matrix are compared and recorded.

That is, in the flow on the right side of the figure, one row of recorded signals is recalled and compared multiple times at the point where pixels in memory>threshold value (J, l). It is processed by the processing section.

In this example, 16 gradations were used, but 32 gradations,
It can easily accommodate 64 gradations or other numbers of gradations.

Further, the present invention is general-purpose and can be easily used not only in inkjet recording apparatuses but also in various recording apparatuses that perform halftone recording.

〔Effect of the invention〕

According to the present invention, the dither method recording circuit can be used to perform not only the dither method recording but also the density pattern method recording without having both the dither method recording circuit and the density pattern method recording circuit, thereby simplifying the circuit. This makes it possible to provide an inexpensive inkjet recording apparatus.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of an inkjet recording apparatus according to an embodiment of the present invention, FIG. 2 is a waveform diagram showing main waveforms thereof, and FIG. 3 is an inkjet recording apparatus according to another embodiment. FIG. 4 is a flowchart of what is shown in FIG. 3. 1...Host, 2...Buffer, 3-6...7-foot register with recycling function, 7...ROM, 8
~9゜15.17, 21... Counter, 10... Comparator, 11... Amplifier, 12... Clock pulse generator, 13... Line signal generator, 14... Frequency division device, 16°20.22...AND gate, 18...decoder, 19...inverter, 23...data selector, 24...switching switch, 25...microcomputer, 26...・Data address bus, 27
...R, AM for work, 28...RO for program
M, 29... People (and 1 other person) Hibiki 7F High School 10th 103rd figure Condolence L+- figure

Claims (1)

[Scope of Claims] 1. A threshold generation circuit that generates a threshold value for a dither matrix, a storage means that stores a recording signal representing density for each pixel, and a storage means that stores a recording signal representing the density for each pixel; In an inkjet recording apparatus that performs dot recording and halftone expression based on the comparison results, one line of recording signal stored in a storage means for storing the recording signal is called multiple times. , an inkjet recording apparatus characterized in that the inkjet recording apparatus is configured to be able to compare each of the values with the threshold values in the dither matrix described above. 2. In the device described in claim 1, a line buffer for at least one line is used as the storage means for storing the recording signal, and any pixel of the stored recording signal,
An inkjet printing apparatus configured to print while comparing all threshold values in a dither matrix corresponding to this pixel. 3. In the item described in claim 1, the threshold generation circuit, the comparison circuit, and the storage means for storing the recording signal are implemented by a microcomputer, a storage element, and an external input/output element. 1 of the configured and memorized recording signals
An inkjet printing apparatus configured to print while comparing all threshold values in a dither matrix corresponding to a pixel.