JPS6284671A - Video printer - Google Patents

Abstract

PURPOSE:To attain density correction ensuring a stable joint between blocks by installing a temperature sensor in the vicinity of the block boundary of a thermal line head and correcting data in the vicinity of the block boundary of a video signal read out of a line memory in accordance with the output of the temperature sensor so as to supply said data to the thermal line head. CONSTITUTION:Among data of one horizontal line of pictures stored in a line memory 8, data on the joint of blocks is transmitted to a data ROM 9, corrected and transmitted to a correction data memory 10. A temperature signal conversion means 19 digitizes and inputs a temperature signal from the temperature sensor 23 in the data ROM 9 at the time of data conversion, and conversion data in accordance with the head temperature at the point is outputted with said digitized signal as an address. In a half tone control means 60, a correction data insertion circuit 12 replaces the data on the joint with joint correction data, and a white data insertion circuit 13 corrects said data into data series suitable to division, and transfers it to the thermal line head 17 through a data processing circuit 15. Finally corrected data is printed.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a dividing printing method of a thermal line head in a full color printer using a thermal line head, and in particular to correction of density at a seam when driving the head in divisions. The present invention relates to a signal processing device having data correction means suitable for.

[Background of the invention]

In the conventional apparatus, as disclosed in Japanese Patent Application Laid-Open No. 58-150572, one line of thermal line heads was divided into two or two blocks and driven for the purpose of reducing peak power.

The operation of wrinkle block printing will be explained in Figures 5 to 6 (c) and (4).The thermal head has 512 heating resistors, and as shown in Figure 5, the heating resistor portions number 1 to 256. The A block 70 is the heat generating resistor portion from 257 to 512 mm, and the B block 71 is the heating resistor portion.

First, the B block 71 of the thermal head is printed, and block 1 is not printed. Next, the A block 70 is printed, and the B block 71 is not printed. By printing one line twice in this way, the peak power flowing to the thermal line head can be reduced to 1/2 of that when printing one line once.

However, the problem here is the joint between the two blocks. As described later, when using a thermal line head, the temperature of the heating resistor at the boundary between the two blocks will be lower than the temperature of the other heating resistor because the resistor on one side does not generate any heat. Sisters,
Print density decreases. In the case of text or white/black only printers, if the temperature of the heating resistor is set above a certain temperature at which saturation density is reached, there will be no difference in print density. However, this method cannot be used with printers that print images with gradations because they apply density gradations, and therefore, a decrease in print density appears as white streaks, which significantly deteriorates the quality of the printed image.

[Object of the Invention] The object of the present invention is to enable stable density correction at the seam between each block, without being affected by the head temperature during printing, in an image printer that prints by dividing the thermal line head into blocks. An object of the present invention is to provide a signal processing device for a video printer.

[Summary of the invention]

A feature of the present invention is that in seam correction in block printing of a video printer using a thermal line head,
Considering the phenomenon that the appropriate correction rate for seam data is affected by the head temperature during printing, a head temperature sensor is installed near the seam, and the correction data is switched based on the detected head temperature. The density correction at the block seam can be stably achieved by continuously supplying current (based on data with a low correction factor applied to the heat generating resistor sandwiching the seam).

[Embodiments of the invention]

An embodiment of the present invention will be explained below with reference to FIG. In the figure, 11d: analog signal processing means, 2: analog/
A digital converter, 6 is an image memory, 4 is a memory control means, 5 is a digital/analog converter, 6 is an analog signal output processing means, 7 is a color selection means, 8 is a line memory,
9 is a data read only memory (hereinafter abbreviated as data ROM), 10 is a correction data memory, 1] is a print control means, +214 correction data insertion circuit, 13 is a white data generation circuit, 14 is a white data generation circuit, 15 16 is a data processing circuit, 16 is a gradation pulse generation means, 17 is a thermal line head, 23 is a temperature sensor, 19 is a temperature signal conversion means, 50 is a seam processing means, and 60 is a halftone control means.

Next, the connection operation will be explained. The image signal input from the video input terminal 73 is processed by the analog signal processing means 1.
The signals are converted into GB color signals, and then converted into RGB digital color signals in the analog/digital conversion circuit 2. The digitized RGB color signals are simultaneously stored in the image memory 3 which is controlled by the memory control means 4. The three-color digital image data stored in the image memory 3 is read out again by the memory control means 4 at the same speed as when recording. Further, the digital/analog converter 5 converts the signal into a three-color analog signal RGH similar to the memory input image, and the analog signal output processing means 6 converts the signal into a video signal, which is then sent to the monitor.

On the other hand, during printing operation, the color selection means 7 selects one color from the read RGB digital signals and stores it in the line memory 8.

Here, the data for one line is data for one vertical line of the image, as shown in FIG. Among these data, the data at the joint portion of the block is sent to the data ROM 9, corrected, and further sent to the correction data memory 10.

When converting data, the data ROM 9JIC inputs the temperature signal from the temperature sensor 23 converted into a digital signal by the temperature signal conversion means 19, and uses this as an address to output converted data according to the head temperature at that time. . One line of image data stored in the line memory 8 is sent to the next stage halftone control means 60. In this halftone control means ω, the correction data insertion circuit 12 exchanges the data of the seam part with seam correction data, and the white data insertion circuit 13 exchanges the data of the seam part with seam correction data, as shown in FIG.
The data is corrected into data strings as shown in Ll and fAI, transferred to the thermal line head 17 via the next stage data processing circuit 15, and printed. Here, thermal line head 1
The energization time 7 is determined by the strobe pulse from the gradation pulse generating means 16.

In the printing operation, as described above, when the data transfer for each block is completed, the data of the next line (the line immediately to the right of the position of the thermal line head in FIG. 2) is taken into the line memory 8. Start printing again.

As shown in the schematic diagram of FIG. 2, the video printer has a thermal head arranged in the vertical direction of the TV screen. Further, the printing direction proceeds sequentially from the left end of the TV screen to the right as shown by arrow A in FIG. 2, and one color printing is completed at the right end.

The thermal printer described in the present invention uses a general color sequential method, and when printing of each of 91 colors is completed by a printing mechanism (not shown), the paper is placed at the original print start position, The next color is printed over the previous color, and three colors are completed), and one print is completed.

Next, the dividing operation will be explained with reference to FIG.

The thermal head has 512 heating resistors as shown in Fig. 5, and the heating resistor parts 1 to 256 are arranged in A block 7G.
, the heating resistor parts from 257 to 512 are placed in B block 7.
Set to 1.

In split printing, first print B block 71, then A block 7.
0 is not printed. (Fig. 6 (Al state) Next, A block 70 is printed. B block 71 is not printed. (Fig. 6 (Al state)
(state of α)) In FIG. 6, Ds represents the data of the th heating element, and α represents the correction factor of the joint portion.

In that case, if seam correction is not performed and there are 10 heating resistors as shown in Figure 9, the central heating resistor 6 adjacent to the resistor 5 which does not generate heat during printing of B block is cooled to the side of A block and printed. concentration decreases. During printing of A block, the resistor 5 is cooled from the B block side, and the printing density decreases, resulting in white streaks. In order to improve this, the density of the seam portion was corrected and the density was made uniform as shown in FIG.

FIG. 8 shows a schematic diagram printed by this split printing method. As shown in the same figure, the seam part is twice for one line,
Portions other than seam 1 will be printed once.

As explained above, one line is printed twice.

Here, the necessity of changing correction data based on temperature will be explained. FIG. 13 shows the relationship between the energization time to the head and the gradation.

In the figure, curve A represents normal data at temperature α, curve B represents normal data at temperature α, curve C represents correction data at temperature α, and curved lines represent correction data at temperature α. Note that the temperature is in the relationship α×b.

In order to print gradation m, the temperature α is ' A s, and the temperature is 1. The joint portion requires a current application time of tc×2 at temperature α and tDX2 at temperature α. Here 1. , 1B, 1c, 1D are J/t
B: The relationship is tc/eB, and the correction data must be changed depending on each temperature.

Here, the correction data can be converted to each gradation depending on each temperature.

The seam density correction method is realized by correcting the input data using the seam self-processing means 50. In other words, the data to be sent to the head of the desired part is corrected in advance by the data ROM 9.

Multiple columns of correction data are written in data RO, M9 according to the head temperature.

As shown in FIG. 12, the head 17 is provided with a heating resistor 75.
A temperature sensor 23 is provided near the seam 76. In this embodiment, as shown in the E-B cross section of FIG. 12 shown in FIG.
A counterbore 78 is provided on the back side of the seam 76 of the heat-sensitive line 17 consisting of 5, and a temperature sensor is placed here. For this reason, the temperature sensor is connected to the seam 7 with a high
Detects the temperature around 6.

The head temperature detected by the temperature sensor 23 TLC is
The temperature signal is digitized by the temperature signal conversion means 19. The above-mentioned correction data group is switched 9 using this temperature signal, and the correction data assigned to the temperature is sent to the correction data memo IJ 10 and held there.

Thereafter, data is transferred from the line memory 8 to the halftone control means ω in accordance with the printing operation as described above. At this time, the timing of the data to be corrected is detected, the correction data insertion circuit 12 is switched, and the correction data memory 10
The correction data from is sent to the data processing circuit 15 at the next stage.

Here, the white data insertion circuit 13 replaces the data transferred to the block that is not printed by the head with white data in advance.

Next, one embodiment of the splice processing means 50 and halftone control means 60 will be described with reference to FIG. In this figure, parts having the same functions as those in FIG. 1 are designated by the same numbers. In FIG. 5, 18 is a data comparator, 19 is a data separator, 20 is a decoder, and 21 is a γ (gamma) read-only memory (
(hereinafter abbreviated as ROM), 22 is a temperature characteristic correction data selector,
23 is a temperature sensor, 8 is a temperature signal amplifier, 2 is an analog/digital converter, 26 is a microcomputer, 2
7 is a gradation control means.

Next, the operation will be explained. Assume that data for one line is currently held in the line memory 8. First, the data group of the head address to be corrected is read out from the line memory 8 and sent to the data ROM 9 by the print control means 1. The data ROM 9 outputs correction data commensurate with the input data and is stored in the correction data memory 10.

The write/read address of the correction data memory IO is determined by the decoder 20. Thereafter, the printing state is entered, and the data from the line memory 8 is sequentially sent to the next stage via the correction data insertion circuit 12.

At this time, when the data to be corrected is transferred, the print control means 1 and the correction data insertion circuit 12 switch their inputs, and the correction data from the correction data memory 10 is selected. These continuous data strings are input to the data comparator 18 via the white data insertion circuit 13. The data comparator 18 compares the input data with the gradation data from the gradation control means n, and outputs energization data of energization ON/Q F F to the heating resistor on the heat sensitive rad 1f. This energization data is transferred to one block by the data separator 29.

After the data transfer to the thermal head 17 is completed, a strobe pulse is output from the gradation pulse generating means 16, and the resistor is energized. After that, the data is transferred again from the line memory 8, and the correction data insertion image j! i! i12, white data insertion circuit 13, data processing circuit 15, thermal head 17
Data is transferred to the resistor and the resistor is energized. Data separator 29
At this time, as shown in Figure 6, body 1, (Al), the white data to the head is sent to the other block, unlike the previous data arrangement.In the case of two block heads, the above two data transfers are performed. Printing of one line is completed.

Next, the temperature control method of the joint self-processing means will be explained.

First, from the line memory 8, the data of the part corresponding to the seam at the beginning of one line transfer is sent in advance to the data ROM 9, which has different data contents for each temperature. On the other hand, the temperature sensor 23 is provided near the joint of the thermal head 17 and constantly outputs a temperature signal. The temperature signal from the temperature sensor 23 is amplified by a temperature signal amplifier 24 to a level necessary for an analog/digital converter, and sent to an analog/digital converter 25 where it is converted into a several-bit digital temperature signal. The converted digital temperature signal is transferred to a microcomputer (hereinafter abbreviated as microcomputer) 26. The microcomputer 26 receives control signals for each line from the print control means 1, and changes the digital temperature signal, which is constantly being sent and changing from the analog/digital converter, for each line.

Here, the reason why the head temperature is changed for each line is that the head temperature rises and changes during printing, but the temperature signal cannot be switched during data transfer, so the temperature signal is changed for each line. Of course, it is also possible to do it for each gradation.

The seam data sent to the data ROM 9 becomes corrected seam correction data, and is transferred to the temperature characteristic correction data selector 22. The microcomputer 2 selects the seam correction data at each temperature transferred to the temperature characteristic correction data selector 22.
Seam correction data suitable for the temperature at that time is selected based on the digital temperature signal from 6 that changes every line, and is stored in the correction data memory 10.

Next, data at the time of printing is sent from the line memory 8 to the correction data insertion circuit 12. At this time, the data of the seam portion is replaced with correction data stored in the correction data memory 10 in advance, sent to the comparator 18, compared with the gradation data from the gradation control means 27, and sent to the data processing circuit 15. It will be done. Data processing circuit 15 separates the data into data 1 and data 2, and transfers them to block A and block B, respectively. At this time, white data from the white data generation circuit 14 is inserted alternately into data 1 and data 2. White data is inserted as data 1 and data 2 for each line, and as shown in FIG. 6, one line is completed by printing B block and A block. On the other hand, gradation data parameters are transferred from the gradation pulse generating means 16 controlled by the gradation data from the gradation control means 27 to the head.

In the above description, the temperature characteristic correction data selector 22 is used to select different correction data, but the data may be selected by address using a large capacity data ROM 9 as shown in FIG.

〔Effect of the invention〕

According to the present invention, when correcting rough data in printing using a video printer using a head divided into two or more blocks, the correction data can be changed depending on the head temperature during printing, so that printing This has the effect that seam correction is possible without being affected by the actual head temperature.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a schematic diagram showing a printing method, Fig. 3 is a block diagram of the splicing self-processing means in Fig. 1, and Fig. 4 is a block diagram showing an embodiment of the present invention. A block diagram showing the splicing self-processing means of another embodiment, FIG. 5 is a schematic diagram of the data arrangement in the head, FIG. 6 is a schematic diagram of the division data arrangement,
Fig. 7 is a correction data transfer timing diagram, Fig. 8 is a schematic diagram of printing, Fig. 9 is a head temperature distribution diagram when joint self-processing is not performed, Fig. 1θ is a head temperature distribution diagram when joint self-processing is performed, ] The figure is a diagram of the relationship between gradation and energizing time, Figure 12, Figure 1
Figure 3 shows the location of the temperature sensor. 9...Data ROM 23...Temperature sensor 2
2...Temperature correction data selector...Temperature signal amplifier 25...Analog/digital converter 26...Microcomputer representative Patent attorney Kotsuki 1 Katsuo 2nd figure 5 figure 6 figure now Wariuchi 15 lites' - Evening tile I @ 8 Fig. 1 Finn No. 9 Fig. 5 puzzles... To the sound of the ring...

Claims (1)

[Scope of Claims] 1. An image memory means for storing a video signal, a line memory connected to the image memory means and storing a part of the video signal stored in the image memory means, and a line memory for storing a part of the video signal stored in the image memory means; a thermal line head divided into at least two or more blocks to which a video signal is supplied;
provided between the line head and the thermal line head,
A video printer comprising a print control means for selectively supplying a video signal from the line memory to the thermal line head block by block, and time-divisionally printing one line of video signal at least twice or more, comprising: A temperature sensor is provided near the block boundary of the line head, and seam processing means corrects data near the block boundary of the video signal read from the line memory according to the output of the temperature sensor and supplies the corrected data to the thermal line head. A video printer characterized by: