JPH0489267A - Color thermal transfer printer - Google Patents

Abstract

PURPOSE:To prevent a printing position from misregistration due to difference of color by a method wherein recording paper is carried by rotating a stepping motor at an equal speed, and heating of a thermal head is controlled by a timing pulse of a cycle equal to recording paper one line carrying cycle with the stepping motor by taking a point when a timing mark formed on recording paper is detected as a start point. CONSTITUTION:By taking a point of time when a photosensor 5 detects a timing mark 6 of recording paper 2 as a start point, a timing pulse for thermal head control of the same cycle as that of a drive timing pulse of a stepping motor 11 is generated from a second timer circuit 13, and heating of a thermal head 3 is controlled following that. Therefore, though a point of time for detection of the timing mark 6 with the photosensor 5 is different, a printing position on each first line of yellow and magenta can be conformed to a position of the thermal head 3 when the photosensor 5 detects the timing mark 6, and misregistration due to difference of color disappears.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color thermal transfer printer that performs recording by applying three or four colors of ink to one surface and then overlapping the other. It is related to improvement.

[Conventional technology]

Figure 5 shows the conceptual structure of a general color thermal transfer printer of this type, in which an ink sheet (1) and recording paper (2) are pressed together by a thermal head (3) and a platen (4). In this state, the ink sheet (1) and the EN paper 12+ are conveyed in the printing direction to the left in the figure by rotating the platen (4) counterclockwise in the figure by the stepping motor, and the photo sensor r51 records the image. When the timing mark [6] provided on the back side of paper r2+ is detected, 1
The printing of the first line is started, and then the second line, the third line, etc. are printed, for example, one yellow page is printed.

Thereafter, the thermal head (3) is separated from the ink sheet CI) and the recording paper C21, and the ink sheet (1) is conveyed in the printing direction so that the next magenta ink can be printed. , rewind in the opposite direction to the printing direction until the timing mark (61) is located to the right of the 7-tooth sensor r51 so that magenta ink can be printed over the printed yellow.

Then, press the thermal head (3) against the ink sheet (1) and the recording paper (21), and press the platen (4) as described above.
Rotate until the photo sensor (5) aligns with the timing mark (6).
) Printing of the first line is started from the time when all the lines are detected, and one page of magenta is printed.

Cyan printing is performed in the same manner.

By the way, in such a printer, as shown in Japanese Patent Laid-Open No. 63-98456 (B41J 3/20), the thermal The head heat generation is controlled.

That is, Figures 6 and 7 show the timing of each part during yellow and magenta printing, respectively, and the drive timing pulse is input to the control circuit of the stepping motor to print the ink sheet (1) and the recording paper. (2), the photo sensor r51 detects the timing mark (6) and the sensor output switches, and after the next drive timing pulse is output, the thermal head (
3), outputs the latch, outputs the heating strobe, and executes the printing operation for the first line.

Thereafter, each time a drive timing pulse is output to the stepping motor, data transfer, latch output, and one heat strobe output are performed to sequentially perform printing operations for the second and subsequent lines.

In addition, in Figures 6 and 7, for simplicity, only one pulse is given to the stepping motor for one line of recording paper (2), and the thermal head (3) is also divided. This is not shown as driving but as batch driving.

[Problem to be solved by the invention]

In the conventional technology described above, printing does not start immediately even when the photo sensor (5) detects the timing mark (6), and the printing operation of each fin is performed based on the subsequent drive timing pulse. Because of this configuration, time delays Ta and Tb as shown in Figures 6 and 7 occur between the time the timing mark (6) is detected and the printing process, and when printing each color. Between the respective time delays that occur, there is a possibility that a shift of one period of the maximum drive timing pulse may be included due to the difference in the timing point at which the timing margin (6) is detected.

On the other hand, the recording paper (
21 is sent stepwise in accordance with the input of the drive timing pulse, and its movement distance has characteristics as shown in FIG. 8.

For this reason, there is a time delay Ta between the time when the timing mark (6) is detected and the time when the timing mark (6) is detected (21 moves, and the timing mark (6) is detected at a different time).
Due to the difference in Tb, the moving distances a and b of the recording paper (2) for each color printing are different, and as shown in Figure 9, the printing positions of yellow and magenta on the recording paper (2) are shifted. Therefore, when three colors of yellow, magenta, and cyan are applied one after another, there is a problem in that it is impossible to eliminate the possibility that the respective printing positions will be shifted by the pitch of feeding of the recording paper (2) by the maximum stepping motor.

In addition, in Fig. 9, the broken line is the timing mark (6)
The position of the thermal head (3) when detected is shown.

The present invention has been made in consideration of these problems of the conventional technology, and its purpose is to provide a color thermal transfer printer that does not cause shading in the printing position due to color differences. There is a particular thing.

[Failure to solve the problem]

In order to achieve the above object, in the color thermal transfer printer of the present invention, the recording paper is conveyed by rotating the stenoping motor at a constant speed, and the timing mark formed on the recording paper is detected by the detection means as a starting point. A timing pulse is generated at a cycle equal to one line conveyance cycle of the recording paper by the step and ping motor, and the heat generation of the timing pulse and thermal head is controlled.

[Effect]

When the timing mark on the recording paper conveyed by the stepping motor is detected by the detection means, a timing pulse with a cycle equal to one line conveyance cycle of the recording paper is output from this point on, and the heat generation of the thermal head is controlled according to this timing pulse. Instead, the printing operation can be performed as soon as the timing mark is detected, and when printing multiple colors, the first line of each is printed at the position of the thermal head on the recording paper when the timing mark is detected. This eliminates the possibility of misalignment of the printing position due to color differences.

〔Example〕

An embodiment will be explained using FIG. 4 instead of FIG. 1.

Note that the same symbol as @ indicates the same or equivalent.

FIG. 3 shows a circuit block of a color thermal transfer printer, in which (7) is a control circuit configured by, for example, a microcomputer, and [8] is data sent to a thermal head (3) according to a thermal head control signal from the control circuit (7). , lunch, and a thermal control circuit that outputs a heat generating strobe; (9) is a sensor input circuit that inputs a sensor input signal to the control circuit r7) according to the sensor input of the photo sensor r51; and αG is a stepping motor that controls the drive of the stepping motor Qll. A motor control circuit, control circuit r7
In response to the stepping motor control signal from the first timer circuit Q2, the motor αD is driven in accordance with a constant cycle timing pulse output from the first timer circuit Q2.

a3 is a second timer circuit, which is activated by the second timer start signal from the control circuit (7) and starts the first timer circuit α.
A timing pulse for controlling the thermal head having the same period as the timing pulse from is inputted to the control circuit (8).

Next, the operation will be explained.

Figure 1 shows a timing chart during yellow printing, in which the control circuit [7] transfers data to the thermal head (3) via the thermal head control circuit (8) in advance and activates the latch. Output.

Thereafter, the control circuit (7) rotates the stepping motor OD by applying a timing pulse from the first timer circuit (c) activated by the first timer start signal to the stepping motor control circuit QOK, thereby printing the ink sheet (1) and recording. Paper (21) is transported.

When the photo sensor r51 detects the timing mark (6) on the recording paper (2), the control circuit (7) that receives this sensor input signal outputs the second timer start signal and starts the second timer circuit a3. The control circuit (7) generates a timing pulse for controlling the thermal head, and the control circuit (7) controls the thermal head control circuit (7) based on this timing pulse.
8) Outputs the heating strobe and prints the ■ line.

When the output of this heating strobe is finished, the data is transferred to the thermal head (3) at the end of the next line, and the launch is output.

After that, when a timing pulse for controlling the thermal head is manually inputted from the second timer circuit 0 to the control circuit C7), the control circuit [7] is sent to the thermal head (3) by two lines via the thermal head control circuit [8). The eye heating strobe is output, the second line is printed, and this process is repeated to complete the printing of one yellow page.

Next, in order to print magenta as shown in FIG. 2, the ink sheet (1) is conveyed and the recording paper (21) is rewound, and the data is previously stored in the thermal head (3) in the same manner as described above. At the same time, the latch is output, the stepping motor OD is rotated according to the timing pulse from the first timer circuit (2), and the ink sheet (1) and recording paper (2+) are conveyed.

When the photo sensor r51 detects the timing mark [61] on the recording paper (2), the second timer circuit 03 is activated, and the first line is printed according to the timing pulse for controlling the thermal head. Line printing is performed one after another, and printing for one magenta color is completed.

In this way, starting from the time when the photo sensor r51 detects the timing mark 161 of the recording paper (21), the second timer circuit α3 turns on the stepping motor +7.
! If the configuration is such that a thermal head control timing pulse having the same period as the dynamic timing pulse is generated and the heat generation of the thermal head (3) is controlled in accordance with this, the first
Even if the detection timing of the timing mark (6) by the photosensor 151 is different as shown in FIG. , the position of the thermal head (3) can be made to match the position of the thermal head (3) when the photo sensor (51) detects the timing mark (6), and there is no possibility of misalignment due to the difference in color.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

The first line is printed at the position of the thermal head on the recording paper at the time when the detection means detects the timing mark on the recording paper, and thereafter, the given line is printed one after another at a one-line transport cycle of the recording paper. If possible, the difference in color may cause the detection means to detect the e5. Even if the printing position of each color is deviated from the driving pulse of the canute soaping motor, the printing position of each color can be aligned regardless of the deviation, and high-quality printing without color unevenness or deviation can be realized.

[Brief explanation of drawings]

1 to 4 show one embodiment of a color thermal transfer printer according to the present invention, FIGS. 1 and 2 are timing charts of yellow and magenta printing operations, respectively, FIG. 3 is a circuit block diagram, and FIG. Figure 4 is a plan view showing the printing position on recording paper, Figure 5 is a schematic side view of a general color thermal transfer printer, Figures 6 and below show a conventional example, and Figures 6 and 7.
The figures are timing charts of yellow and magenta printing operations, respectively. Figure 8 is a diagram showing the relationship between the driving pulse of the stepping motor and the moving distance of the recording paper. Figure 9 is a plan view showing the printing position on the recording paper. . (2) ff1i, (3) - thermal head,
(5)・Photo sensor, (6)・Timing mark, 0
1) Stepping motor.

Claims (1)

[Claims] (1) In a color thermal transfer printer that performs recording by sequentially coating multiple colors of ink, a stepping motor is rotated at a constant speed to convey a recording paper, and a timing mark formed on the recording paper is detected by a detection means. A color thermal transfer printer characterized in that a timing pulse is generated at a cycle equal to a one-line conveyance cycle of the recording paper by the stepping motor starting from the time of detection, and heat generation of the thermal head is controlled by the timing pulse.