JPS6381065A - Thermal transfer recorder - Google Patents

Abstract

PURPOSE:To reduce the number of component parts to prevent an image plane from being affected by the error of a sensor mounting position etc., by a method wherein, the rotation number of a motor is counted after a recording paper detection sensor detects a recording paper, and according to the counted value each thermal head is controlled. CONSTITUTION:A recording paper detection sensor 7 is disposed on a position upstream of a first thermal head 2 in the recording paper carrying direction. A platen 1 connected to a stepping motor 8 through a timing belt 9 starts rotating when the leading end of a recording paper is detected by the sensor 7. A fixed function exists between the drive pulse supply number to the motor 8 and the rotation number of the motor 8 and between the rotation number and the recording paper carrying distance from the sensor 7 to respective thermal heads 2, 3, and 4. Therefore, if the drive pulse supply number to the motor 8 is counted, the present position of the recording paper is obtained according to the counted value. A control circuit 5 counts the drive pulse number to the motor 8 to control the execution/release of the pressure contact of the thermal heads 2, 3, and 4 against the platen 1 with the counted value coincident with a predetermined pulse number.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal transfer recording device, and more particularly to a thermal transfer recording device that is capable of multicolor printing and is equipped with a plurality of thermal heads along a recording paper conveyance path.

2. Description of the Related Art In this type of thermal transfer recording device, for example, three thermal heads are arranged along the conveyance path of recording paper, and the first thermal head prints yellow, the second thermal head prints magenta, and the third thermal head prints yellow. In a color printer whose head prints in cyan color, there is a problem in that printing misalignment in one thermal head disrupts the color balance of the recorded image, making it impossible to reproduce the desired image. For this reason, care should be taken to avoid printing misalignment with each thermal head. Conventionally, there is a device that takes this kind of consideration into consideration, as disclosed in Japanese Unexamined Patent Publication No. 134274/1983. In this conventional means, a sensor for detecting recording paper is provided in the vicinity of each thermal head, and when the sensor detects recording paper, the thermal head closest to the sensor is controlled to be pressed against the platen. According to this conventional means, even if the amount of rotation of the platen placed opposite the thermal head differs between the thermal heads,
Since the pressure contact of the corresponding thermal head to the platen is independently controlled by the sensors provided on the thermal heads in a one-to-one relationship, it is possible to prevent printing misalignment for each thermal head.

However, according to the conventional means described above, as many recording paper detection sensors as there are thermal heads are required, which increases the number of parts and increases the cost. There are problems in that errors in mounting position and variations in detection performance affect image quality.

Therefore, an object of the present invention is to provide a useful thermal transfer recording device that can reliably solve the above problems.

Means for Solving Problems 5 to 5 In order to achieve the above object, the thermal transfer recording apparatus of the present invention includes a plurality of thermal heads disposed along a conveying path of recording paper, and a plurality of thermal heads disposed along the conveying path of recording paper. A recording paper detection sensor provided upstream of a thermal head located at the most upstream side of a recording paper conveyance path; The recording paper detection sensor is characterized in that after detecting the recording paper, the amount of rotation of the motor is counted, and each of the thermal heads is controlled based on the counted value.

The operation of the present invention will be explained in detail in Examples.

Figure 1 shows a drum-shaped multi-head type thermal transfer recording device as an embodiment of the present invention, in which a drum is placed at an angle of 90'' around one platen 1 in the conveyance direction P to the recording paper. First, second, and third thermal heads 2, 3, and 4 are arranged along the platen 1. Each of the nozzles 2 to 4 is brought into and out of pressure contact with the platen 1 by a control signal from a control circuit 5.

A yellow ink film 23 wound between the supply reel 21 and the take-up reel 22 is installed at the tip of the first thermal head 2, and a yellow ink film 23 is installed between the supply reel 31 and the take-up reel 32 at the tip of the second thermal head 3. A magenta ink film 33 wound around is installed, and a cyan ink film 43 wound around between a supply reel 41 and a take-up reel 42 is installed at the tip of the third thermal head 4. A recording paper guide 6 is provided on the circumferential surface of the platen 1 between each thermal head 2, 3.4, and the recording paper A is wound around the circumferential surface of the platen 1 and is conveyed as the platen l rotates. This is to avoid paper jams, etc.

Upstream of the recording paper transport from the first thermal head 2 (arrow P
In the opposite direction), one recording paper detection sensor 7 is provided at a predetermined position.

The platen 1 is connected to a stepping motor 8 via a timing belt 9, and starts rotating when the starting edge of the recording paper is detected by the sensor 7. There is a certain relationship between the amount of drive pulses supplied and the amount of rotation of the stepping motor 8, and there is also a certain relationship between the amount of rotation and the recording paper transport distance from the sensor 7 to each of the thermal heads 2, 3, 4. Therefore, by counting the number of drive pulses supplied to the stepping motor 8, the current position of the recording paper can be determined from the count value.The control circuit 5 counts the number of drive pulses supplied to the stepping motor 8, and If the value matches the predetermined number of pulses, the thermal heads 2 and 3
．． 4 to the platen 1 and release of the pressure contact.

FIG. 2 is a flowchart illustrating the press-contact and press-release operations of each thermal head. As shown in Figure (A), first, when the power is turned on, recording paper A is fed from a cassette (not shown) (Sl). When the recording paper detection sensor 7 detects the starting edge of the recording paper A (S2), the stepping motor 8 starts rotating the platen 1 in the direction P in FIG. At the same time, a counter in the control circuit 5 starts counting the number of driving pulses of the stepping motor 8.

When the count value K of the counter reaches a predetermined value Y (34
), a control command is issued from the control circuit 5 to the thermal head 2, the thermal head 2 is brought into pressure contact with the platen 1, and prints in yellow at a predetermined position on the conveyed recording paper.

Next, when the count value K of the counter reaches a predetermined value M due to the rotation of the stepping motor 8 (S5), the thermal head 3 comes into pressure contact with the platen 1, and the recording paper that has been conveyed to the head position is placed in a predetermined position. Print magenta at the position. Similarly, when the count value K of the counter reaches C (S6), the thermal head 4 comes into pressure contact with the platen 1 and prints in cyan at a predetermined position on the recording paper that has been conveyed to the bottom 4 position.

Then, the three colors of ink are superimposed on the recording paper A, and a predetermined image is formed by the composite color.

The pressure welding of each of the thermal heads 2, 3, and 4 above is shown in Figure 2 (b).
This is done according to the flowchart.

Next, after each thermal head 2, 3.4 is pressed against the platen 1, the pressure contact is sequentially released when the pulses corresponding to the length of the recording paper are counted by the counter (S7).

FIG. 3 shows another embodiment of the present invention. In this embodiment, in addition to the configuration of the first embodiment, a third thermal head 4 is provided.
A recording paper jam detection sensor 1 is installed downstream of the recording paper conveyance.
0 is set. If the recording paper A does not jam while being conveyed, the number of pulses from when its starting edge is detected by the upstream sensor 7 to when it is detected by the downstream sensor 10 is fixed.

Therefore, even if the number of pulses reaches that value, the downstream sensor 10
If the start edge of the recording paper is not detected, it can be determined that there is a jam.

FIG. 4 shows yet another embodiment of the present invention. This embodiment is called a flat multi-head type, and has thermal heads 2, 3, and 4 arranged in a horizontal row. Then, a platen la is placed opposite each thermal head 2, 3゜4.
, lb, and lc are provided, but each platen 1a to I
Unlike the conventional one, C is connected to one stomping motor 8 via a timing belt 11, and is rotationally driven by the second stomping motor 8. The conveyance direction of recording paper A is the direction indicated by arrow Q in the figure.

In all of the above embodiments, the platen is driven by a stamping motor, but it goes without saying that motors other than the stamping motor can also be used if they are combined with a pulse encoder so that the amount of rotation of the motor can be detected. Nor.

Further, although each of the above embodiments has three thermal heads, the present invention can be applied to any device having two or more thermal heads.

1.9] As explained above, according to the thermal transfer recording device according to the present invention, one recording paper detection sensor is sufficient regardless of the number of thermal heads, a single platen drive motor is required, and only one component is required. The effects include a significant reduction in the number of devices, miniaturization of the device, and lower cost.

Furthermore, since one recording paper detection sensor is shared by all the thermal heads, even if the mounting position of the recording paper detection sensor is slightly misaligned, the effect will be the same on all the thermal heads, and therefore the image quality will be affected. has the effect of having no effect.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a positional embodiment of a thermal transfer recording apparatus of the present invention, FIG. 2 is a diagram showing a flowchart, and FIGS. 3 and 4 are diagrams showing other embodiments of the present invention. ■...Platen, 2, 3.4...7F to thermal,
7... Recording paper detection sensor.

Claims (1)

[Claims] (1) A plurality of thermal heads disposed along a recording paper conveyance path, a platen disposed facing each thermal head via the conveyance path, and one motor that drives the platen. and a recording paper detection sensor provided upstream of the thermal head located at the most upstream side of the recording paper conveyance path, and after the recording paper detection sensor detects the recording paper, it counts the amount of rotation of the motor. , a thermal transfer recording apparatus characterized in that each of the thermal heads is controlled according to the count value.