JPS59111872A - Thermal transfer type printer - Google Patents

Abstract

PURPOSE:To enable to represent accurate density variation, by a method wherein the timing of starting to pass an electric current is controlled so that a center line of transfer dots of heating resistors becomes substantially rectilinear. CONSTITUTION:Digital video signals in a data memory device 22 are sequentially accessed by an address counter 24, and are fed through an inverting circuit 23 into a density variation data comparing circuit 25, which compares them with an utput from a data counter 26 controlled with respect to counting-up or the like by an UP/DOWN change-over circut 29. According as inverted data are smaller or larger than the output of the counter 26, a signal ''1'' or ''0'' is supplied to a shift register circuit 27, and gates G1, G2... corresponding to the heating resistors R1, R2... impressed with heating pulses are controlled through a latch circuit 28. Said operation is repeated each time the counter 26 counts up, and the same applies to each counting-down of the counter 26 under the action of the circuit 29. Accordingly, the timing of starting to pass electric currents to the heating resistors is controlled in accordance with the density variation of the dots, the center line of transfer dots becomes substantially rectilinear, and accurate density variation is represented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal transfer printing device, which transfers heat-melting ink onto recording paper almost simultaneously by passing current through a plurality of heat-generating resistors to form a plurality of pixels. In the pattern printing device, by controlling the point in time when current starts flowing through the heat generating resistors (/rC) so that the center line of the transferred pixel is approximately in a straight line,
In other words, for example, an open current is applied to the heat generating resistor corresponding to a portion with a high color density from an early stage until late, and an open current around the midpoint is applied to a heat generating resistor corresponding to a portion with a light color density. It is an object of the present invention to provide a thermal transfer type printing device in which the gradation of an image printed with gradation display is accurate and the transferred image is excellent.

As shown in FIG. 1, the principle of a thermal transfer type printing device is as follows: A pressure roller 3 is used to overlap recording paper 1 and transfer paper 2.
When the transfer paper 2 is heated by passing current through each heating resistor R1, R2゜...', L of the thermal head 4, the transfer paper 2 is coated. The hot-melt ink 2' is melted, and the hot-melt ink 2' is attached to the recording paper 1 to form a printed matter. Similarly, the unnecessary transfer paper is passed through the guide roller 5 and taken up by the winding roller 6.
It is wound up.

Printing with this thermal head is as shown in Figure 2.
An analog video signal obtained by a TV signal generator 20 such as a TV camera or VTR is converted into a digital signal by an A/D converter 21, and this digital signal is sent to a data storage device 22 such as a semiconductor memory. When the addresses for the required number of pixels are determined and stored, and a start pulse is added to the address counter 24 (and a reference clock is sent to the address counter 24, the address counter 24 reads 1).
The address of the second time is sent to the data storage device 22, the data stored at that address is sent back from the data storage device 22, and this data is sent to the grayscale data comparison circuit 25. At this time, the count of the data counter 26 is set to O, and the gray data comparison circuit 25 compares the data sent back from the data storage device with the data (0) from the data counter 26.
If the data from the data counter 26 is different or thicker than the data from the data counter 26 (count O), a signal of 1 is sent to the shift register circuit 27, and if it is smaller, a signal of 1 is sent to the shift register circuit 2.
Send an O signal to 7. Then, the address counter 24 indicates the heating resistor R, R2, . . . of the thermal head.
... + After counting the total number n of Rn, one data transfer pulse is sent to the latch circuit 28. Also, at the same time as sending the first data transfer pulse, a heating pulse is generated)G+
, G2,...

Send to Gn.

Thereafter, in the same manner, each time the address counter 24 finishes counting n, the count of the data counter 26 is increased by one, and if the maximum color density is m, the address counter 24 counts n m times, and the data counter 2
The number 6 and the data of each address sent back from the data storage device 22 are compared each time by the density data comparison circuit 25, and it is determined whether the data from the data storage device 22 is thicker than the count number from the data counter 26 or not. If it is smaller, it sends a signal of 1 to the shift register circuit 27, and if it is smaller, it sends a signal of O. Then, when the address counter 24 has finished counting the total number n of the heating resistors R,, R2, ..., Ro of the thermal head, one data transfer pulse is sent to the latch circuit 28, and at the same time the heating Pulse game 1
'G1. G2, ``'''', send to Gn.

In this way, the heating resistors R,, R2,...
.

A current is passed through Ro for a predetermined period of time to heat it, and the recording paper 1 is fed in the direction of the arrow at a speed of 2, in close contact with the hot-melt ink 2' of the transfer paper 2, between the thermal head 4 and the pressure roller 3. If the time required for the address counter 24 to reach the number n] is t, dots of length mvt are transferred at the portion corresponding to the maximum color density, and at the portion corresponding to the minimum color density. In the area, dots with a length vt are transferred, and dots with a length that is an integral multiple of vt are transferred according to each color density, resulting in area gradation that changes the color density per unit area. Can record.

However, the arrangement of dots printed by such a thermal transfer printing device is as shown in Figure 3, in other words, the length of each dot (the length of the dot in the direction of movement of the recording paper 1) is proportional to the size of the data value. Although it is accurate, since the transfer start point of each dot is the same, the center line of each dot (indicated by a dashed line) looks like a broken line,
Therefore, with this arrangement of dots, the position of a dot with a certain shading in the overall image changes slightly, and even if the shading of each dot is accurate, the position of that shading is not accurate. Overall, accurate shading cannot be displayed.

The present invention eliminates the above-mentioned drawbacks, and examples thereof will be described below.

FIG. 4 is a block diagram of one embodiment of the thermal transfer printing device according to the present invention, and FIG. 5 is an explanatory diagram of an example of transfer by the thermal transfer printing device according to the present invention.

That is, an analog video signal obtained by a TV signal generator 20 such as an RV camera or a VTR is converted into a digital signal by an A/D converter 21, and this digital signal is sent to a data storage device 22 such as a semiconductor memory. Then, set and store addresses for the required number of pixels, add a start pulse to the address counter 24, and send a reference clock to the address counter 24.
4 sends the first address to the data storage device 22, and the data contained in that address is sent back from the female data storage device 22.

The data sent back from the data storage device 22 is inverted by the inverter circuit 23 (assuming that the data from the data storage device 22 is 1011, for example,
When this is inverted (0100), this inverted data is sent to the grayscale data comparison circuit 25. And at this time,
UP, 4) The count of the data counter 26 whose output is set to the UP state by the N switching circuit 29 is set to O, and this count O and the inverted data are compared by the gray data comparison circuit 25, and the inverted data is the data. If it is smaller than the data from the counter 26, a signal of 1 is sent to the /ft register circuit 27, and if the inverted data is thicker than or equal to the data from the data counter 26, a signal of 1 is sent to
Send issue g.

Then, when the address counter 24 has finished counting the total number n of the heating resistors R, R2, . . . , Rn of the thermal head 4, a data transfer pulse is sent to the latch circuit 28.
Send one to. Also, at the same time as sending the first data transfer pulse, a heating pulse is applied to the gates G, , G2 . .......

Send to Gn. Thereafter, in the same manner, the address counter 24
Each time the count i of n is completed, the count of the data counter 26 is increased by one, and the count number corresponding to the maximum color density is set to m, and the count of the counter 240n is performed m times.

When the count of the data counter 26 reaches m, the data counter 26 is turned down by the LIP/11)N switching circuit 29, and the count m of the data counter 26 and the data storage device 22 are removed from the inverter circuit 23. The grayscale data comparison circuit 25 compares the inverted data with the inverted data sent back via the data counter 26, and if the inverted data is smaller than the count m of the data counter 26, a signal of 1 is sent to the shift register circuit 27, and the inverted data is If the count is equal to m from the counter 26, a signal O is sent. Then, the address counter 24
The resistance F1. ．． G1. G2.・
...l Send to Gn. In this way, each time the address counter 24 counts n, the output of the data counter 26 is decremented by 1, and the counted numbers are m-i, m-
2, . send,
If the inverted data is greater than or equal to the count from the data counter 26, a 0 signal is sent.

With such a system, a current is passed through the heating resistors R, , R2, . When the recording paper and the transfer paper are pressed together with a pressure roller and moved at a speed of V, if the time taken for the address counter 24 to count n is t, then as shown in FIG. 5, it corresponds to the maximum color density. A dot with a length of 2 mVt is transferred in the part corresponding to the minimum color density, and a dot with a length of 2 mVt is transferred in the part corresponding to the minimum color density, and the length is an integral multiple of 2vt depending on the color density. The dots are transferred, and area gradation recording with varying color density per unit area can be achieved.

Moreover, in such a transfer example, the heating resistor R,
, R2, . . . Rn is controlled according to the coloring density, so that the heating resistors R, , R2, . . . , Rn configured in a line shape The center line of each dot (indicated by a dashed line in Fig. 5) transferred by the method becomes a - straight line, and the position of the dot for displaying shading in the entire image is accurate, so the entire image is If we look at it as follows, we can see that accurate shading can be displayed.

When the output of the data counter 26 becomes 0, the address of the address counter 24 is set as the address of the next line,
Also, with the data counter 26 in the up configuration, the same operation as above is repeated to create seven images.

Furthermore, in the above embodiment, the length of each dot is twice that of the system shown in Fig. 2, but this is due to the fact that the feeding speed of the recording paper is increased or the clock speed is increased. By doubling the frequency of the pulses and reducing the counting time of n, the system of FIG. 2 can be obtained with dots having the same area.

As described above, the thermal transfer printing device according to the present invention causes the heat-melting ink of the transfer paper to adhere to the recording paper by passing current through the heat-generating resistor of the thermal head provided with a plurality of heat-generating resistors. In a thermal transfer printing device that performs printing, the point at which current is started to flow through the plurality of heat generating resistors so that the center line of the transfer dot of the heat-fusible ink by the plurality of heat generating resistors becomes approximately linear. Since the transfer dots are provided with a means for controlling the transfer dots, the position of each transfer dot is accurate, and the shading of the entire image made up of a large number of transfer dots is accurate, resulting in an excellent transfer image. It has the advantage of displaying gradation close to the actual image and being easy to view.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of a thermal transfer printing device, FIG. 3 is an explanatory diagram of an example of transfer by the system in FIG. 2, FIG. 4 is a block diagram of a thermal transfer printing device according to the present invention, and FIG. The figure is an explanatory diagram of an example of transfer by the thermal transfer printing device of the present invention. 21... A4 conversion device, 22... Data storage device, 2
3... Inverter circuit, 24... Address counter, 25... Grayscale data comparison circuit, 26... Data counter, 29... UP/DN switching circuit. Patent applicant: Japan Victor Co., Ltd. Agent: Katsu Uko! Self,
・Continued from page 1 0 Inventor: Shigeru Kato, Japan Victor Co., Ltd., 3-12 Moriya-cho, Kanayo-ku, Yokohama City 0 Inventor: Tsutomu Kiuchi, Japan Victor Co., Ltd., 3-12 Moriya-cho, Kanayo-ku, Yokohama City

Claims (1)

[Claims] In a thermal transfer printing device that prints by applying a current to the heat-generating resistor of a thermal head provided with a plurality of heat-generating resistors to attach the heat-melting ink of the transfer paper to the recording paper,
The present invention is characterized by comprising means for controlling the point in time when current starts flowing through the plurality of heat generating resistors so that the center line of the transfer dot of the heat-melting ink by the plurality of heat generating resistors becomes substantially linear. A thermal transfer printing device.