KR0132893B1 - Video printer device - Google Patents

Abstract

Disclosed is a video printing apparatus. The apparatus comprises a thermal transfer head and a print control circuit. In the thermal transfer head, a predetermined number of heaters to print a line are divided into several groups for a sequential heating. The print control circuit controls one portion of the groups by comparing the image signal to data from low gray scale to high gray scale. Also, the print control circuit controls the other portion of the groups by comparing the image signal to data from high gray scale to low gray scale. Thereby, continuous instantaneous current flows into the thermal transfer head, so that the print quality can be improved.

Description

Video printer device

1 is a block diagram of a conventional video printer apparatus.

2A to 2C are diagrams for explaining the instantaneous current value flowing through the thermal transfer head (TPH) at the time of printing by the apparatus shown in FIG.

3 is a block diagram of a video printer apparatus according to an embodiment of the present invention.

4A to 4C are diagrams for explaining the instantaneous current value flowing through the TPH at the time of printing by the apparatus shown in FIG.

5 is a detailed circuit diagram of the TPH shown in FIG.

6 is a waveform diagram of signals applied to the TPH shown in FIG.

* Explanation of symbols for main parts of the drawings

210, 220: first and second line memory 230: address generator

240: system controller 250, 260: first and second gradation counter

270, 280: first and second tone comparator 290: TPH (Thermal Print Head)

300, 310: first and second strobe signal generator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sublimation thermal transfer video printer apparatus, and more particularly, to a video printer apparatus capable of expressing a constant tone for each gradation by controlling a constant instantaneous current to flow through the thermal transfer head for each gradation during line printing. .

Generally, a sublimation type thermal transfer printer that prints using a thermal print head (hereinafter referred to as TPH) is a device that performs printing, and dye is applied by energy generated by TPH by applying energy to TPH. Sublimation of the dye of the film is made to obtain the desired image or picture by the amount of the dye is transferred to the recording paper.

As shown in FIG. 1, the video printer apparatus reads data for a line from a frame memory (not shown) storing video signals transmitted from a signal input source in units of frames, and is generated in the address generator 130. FIG. According to the write address, the first and second line memories 110 and 120 are divided into 1/2 lines and stored.

In the first and second gray scale comparators 160 and 170, the first and second gray level comparators are compared with the gray scale data preset from the gray scale counter 150 and the outputs of the first and second line memories 110 and 120. And output to the data input terminals of the second blocks 181 and 182.

Here, the first and second blocks may include a shift register (not shown) for storing serial data of the formulation 1 and second tone comparators 160 and 170 in units of one line, and an output of the shift register (not shown). A latch register for latching and a heating element (not shown).

In the TPH 180, when one line of data from the first and second grayscale comparators 160 and 170 is input to the shift register according to the clock signal CLOCK, a latch signal LATCH is generated, which is not shown in the drawing. The TPH 180 generates a heating element for a low level period, which is an active period of the strobe signal STROBE, according to data input to the latch register.

Here, the TPH 180 is composed of a large number of heating elements (resistance), and energy must be applied to the heating elements for gradation expression.

If the instantaneous current is calculated to represent one gray level, the instantaneous current is approximately 10A if the voltage applied to TPH is 24V, the resistance of TPH is 3000OHM, and the number of heating elements of TPH is 128 0 dots (DOTS). . The instantaneous power is about 240W (Watt).

At this time, the instantaneous current value flowing through the TPH at the time of one line printing is shown in FIGS. 2A to 2C. That is, since a typical image has data of less than 180 gray scales, the gray scales of the first and second blocks 181 and 182 are simultaneously represented from 1 gray scale to 256 gray scales, as shown in FIGS. 2A and 2B. Likewise, most of the current flows in the first half of the 1-line printing time, and as shown in FIG. 2c, the instantaneous current value is high in the first half of the first line. There is a problem that results in deterioration of image quality.

In order to overcome the above-mentioned problems, an object of the present invention is to print high and low gray levels simultaneously so that the instantaneous current value is uniformly reduced in the thermal transfer head for each gray level during line printing, thereby reducing the noise caused by the high current. The present invention provides a video printer device.

In order to achieve the above object, the video printer device according to the present invention is to input the image signal from the signal input source to store the line unit and express the energization factor to the thermal transfer head composed of a heating element after comparing the gray level value and the gray level in advance In an apparatus; A thermal transfer head unit which generates heat by dividing a predetermined number of heating elements required to represent one line into a predetermined number of blocks; For a predetermined number of blocks of the thermal transfer head portion, some blocks output the comparison output to the thermal transfer head in comparison with the preset gray level values in the order of low to high gray levels, and the remaining blocks are in the order of high to low gray levels. And a print control circuit for outputting a comparison output to the thermal transfer head portion in comparison with a preset gray scale value.

Hereinafter, a preferred embodiment of a video printer apparatus according to the present invention will be described with reference to the accompanying drawings.

3 is a block diagram of a video printer apparatus according to an embodiment of the present invention.

3, the first and second line memories 210 and 220 read out and store lines from a frame memory (not shown) in which an external image signal is input and stores signal processed signals on a frame basis; An address generator 230 for generating write / read addresses of the first and second line memories 210 and 220; A system controller 240 for outputting signals for controlling writing / reading of the first and second line memories 210 and 220; A plurality of gradation counters 250 and 260 for outputting gradation data of a predetermined step according to a control signal output from the system controller 240; First and second tone comparators 270 and 280 for comparing the data read out from the first and second line memories 210 and 220 with the tone data previously stored in the first and second tone counters 250 and 260; First and second strobes that generate a strobe signal corresponding to a heat generation time for generating TPH while the outputs of the first and second tone comparators 270 and 280 are input to the first and second blocks of the TPH 310. Signal generators 290 and 300.

The first line memory 210 to the second straw signal generator 300 belong to a print control circuit (or TPH control circuit).

Next, the operation of FIG. 3 will be described with reference to FIGS. 4 to 6.

According to FIG. 3, although the color video printer according to the present invention is not shown in the drawing, the video signal processing means in which a digital signal is stored in units of frames after A / D conversion of an image signal flowing from a signal input source; A video display means for displaying a signal processed signal is provided. The video signal processing means and the video display means are well known and thus will be omitted here.

In the first and second line memories 210 and 220, data read from the frame memory is stored at an address corresponding to a write address generated by the address generator 230 according to a write enable signal output from the system controller 240. Store in line units. In other words, in order to represent one line, if it is composed of 512 pixels, the first line memory stores the first to 256th pixels, and the second line memory stores the 257th to 512th pixels. Each pixel is represented by 8 bits.

The first gradation counter 250 outputs gradation data from 1 gradation to 256 gradations so as to express 256 gradations for the 1st to 256th pixels, and the second gradation counter 260 outputs gradation data from 256 gradations to 1 gradation. Outputs

The first gradation comparator 270 compares the output of the first line memory 210 with the output of the first gradation counter 250 and outputs it to the TPH 310, and the second gradation comparator 280 uses the second line memory. The output of the 220 and the output of the second gradation counter 260 are compared and output to the TPH 310.

That is, the first gradation counter 250 starts from low gradation, and when one gradation is expressed, increases the counter to high gradation and sends it to the first gradation comparator 270, and the second gradation counter 260 starts from 256 gradations. By using the low counting down counting to reduce the gradation is sent to the second grad comparator 280.

Therefore, the first and second gradation comparators 270 and 280 simultaneously express 1, 256 gradations, 2, 255 gradations .... and 256, 1 gradations in the order of 128, 128 gradations. Will be done.

In the first and second gray level comparators 270 and 280, the gray level compared data is transmitted to the first and second blocks of the TPH 310 by a clock signal CLOCK, and all data for one line are transferred to the TPH 310. After the transfer is completed by latching by the system controller 240 to finish the heating.

Subsequently, the first and second strobe generators 310 and 320 transmit the energized pulses for a time appropriate to the gray level corresponding to the data transmitted to the first and second blocks, respectively, to express the printing.

When one gray scale expression is finished, the first gray scale counter 250 increases one gray scale and the second gray scale counter 260 decreases one gray scale to perform the next gray scale expression.

If you repeat 255 times, 256 gradation expressions of one line for one color will be finished, and you will move to the next line.

On the other hand, Figure 4a shows the instantaneous current flowing through the first block representing from 1 gradation to 256 gradations, while Figure 4b shows the current order flowing through the second block representing from 256 gradations to 1 gradation.

Here, since the second block of the TPH 310 prints in the opposite direction to the first block from 256 to 1 gray, the second block of the TPH 310 flows to the TPH 310 as shown in FIG. The current flows evenly over the factor expression time, reducing the instantaneous current value.

5 is a detailed circuit diagram of the TPH shown in FIG.

Referring to FIG. 5, the first shift register 311 stores the serial data shown in FIG. 6A output from the first grayscale comparator 270 according to the clock signal CLK shown in FIG. 6C. The second shift register 312 stores the serial data shown in FIG. 6B output from the second grayscale comparator 280 according to the clock signal CLK shown in FIG. 6C.

When the first and second shift registers 311 and 312 are input to the first to 512th signals for one line, they are latched to the latch register 313 by the latch signal LATCH shown in FIG. 6D.

The first driving circuit 314 generates heat during the heating period of the first strobe signal STROBE1 and the second driving circuit 315 generates heat according to the output of the latch register 313 during the heating period of the second strobe signal STROBE2. 316 is heated.

As described above, the video printer device according to the present invention reduces power required instantaneously and at the same time reduces the current flowing through the TPH to reduce noise caused by a large current and to reduce the load of the power supply stage to supply stable power and high quality. The cost can be reduced by lowering the power supply capacity.

In addition, the present invention reduces the number of dots to be printed at the same time, so that the effect of the common resistance is also reduced, that is, when the heating element of the TPH generates a lot of heat, the voltage applied to the common resistor changes, resulting in deterioration of image quality, unlike the conventional video printer apparatus. It is also possible to achieve high image quality by reducing the change in TPH voltage.

Claims (4)

In a device that inputs an image signal from a signal input source and stores it line by line, and expresses a conduction factor in a thermal transfer head composed of a heating element after comparing the gray level with a preset gray level value, a predetermined number of heating elements required to represent a line are predetermined. A thermal transfer head unit which generates heat by dividing into blocks; For a predetermined number of blocks of the thermal transfer head portion, some blocks output the comparison output to the thermal transfer head in comparison with the preset gray level values in the order of low to high gray levels, and the remaining blocks are in the order of high to low gray levels. And a print control circuit for outputting a comparison output to the thermal transfer head portion in comparison with a preset gradation value. 2. The apparatus of claim 1, wherein the print control circuit comprises: a plurality of line memories for storing signals processed from a signal input source into lines corresponding to the plurality of blocks; A plurality of gradation counters for counting data stored in the plurality of line memories from low gradation to high gradation or from low gradation to high gradation; A plurality of gray level comparators for comparing the gray level data output from the plurality of gray level counters and data stored in the plurality of line memories; At least one strobe signal generator for controlling a heat generation time of the thermal transfer head divided into the plurality of blocks according to the output of the grayscale comparator; And system control means for controlling data writing and reading of the plurality of line memories and controlling the gradation order of the plurality of gradation counters. 3. The strobe signal generator of claim 2, wherein the strobe signal generator has a heat transfer head divided into the plurality of blocks, and some blocks represent heat generation time corresponding to a sequence of low to high gradation in order of remaining blocks. And a strobe signal for outputting. The apparatus of claim 1, wherein the thermal transfer head unit comprises: a plurality of shift registers storing serial data output from the plurality of grayscale comparators; A latch register for latching one line of data simultaneously in one line in the plurality of shift registers; A plurality of driving circuits for driving the output of the latch register by a strobe signal generated by the at least one strobe signal generator; And a predetermined number of heating elements driven by the plurality of driving circuits.