JPS6295281A - Color thermal transfer recording apparatus - Google Patents

Abstract

PURPOSE:To effectively prevent the color misregistration of a reproduced image, by providing an electric control circuit for connecting a rotary encoder to the small roller contacted with a platen roller under pressure through recording paper and measuring the number of output pulses of the rotary encoder to control the quantity of rotation of a pulse motor for feeding recording paper. CONSTITUTION:A pulse motor 14 is driven so as to perform feeding by one pitch line by applying a plurality of pulses to said pulse motor 14. Now, when a plurality of pulses (herein, N=4) are generated from a pulse generating circuit 11, the pulse motor 14 rotates by 4 steps through a pulse motor driving circuit 12. Each of feed quantities of recording paper 5 and thermal transfer paper at this time just correspond to a line pitch. The feed quantity of the recording paper 5 is measured by a small roller 9 and a rotary encoder 10 and the number of generated pulses of the pulse generating circuit 11 are controlled on the basis of the measured result to increase and decrease the angle of rotation of the pulse motor 14 and the feed quantity of the recording paper is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color thermal transfer recording device that performs recording by transferring coloring material on a thermal transfer paper onto a recording paper using a thermal print head.

[Prior Art] Conventionally, there is a color thermal transfer recording device of this type as shown in FIG. 4. In FIG. ) are the supply roller and take-up roller for the thermal transfer paper (2), (5) is the recording paper, and (6) is the roller for pressing the thermal transfer paper (2) and the recording paper (5) against the thermal print head (1). The platen roller (7) is the capstan roller, (8
) is a pinch roller.

Next, the operation will be explained. Capstan roller (7)
is driven by a pulse motor (not shown). The recording paper (5) pressed against the capstan roller (7) by the pinch roller (8) is sent in the direction of the arrow in the figure by the rotation of the capstan roller (7). The platen roller (6) and capstan roller (7) are connected, and the platen roller (8) handles the recording paper (5) and the thermal transfer paper (
2) is brought into pressure contact with the thermal print head (+), while the recording paper (5) and the thermal transfer paper (2) are conveyed at the same speed in the directions of the arrows in the figure. At the same time, heat transfer paper (2
) E- coloring material is melted by the heat generated by the thermal print head (1), transferred to the recording paper (5), 1 m long, and then transferred to the recording paper (5), 1 m long.
5) Characters and images are formed on L.

By the way, the thermal transfer paper (2) has Y(
Yellow) 9M (magenta) and C (cyan) color materials are applied in the same area as one page, and images of one Y component and one C component are overlaid in sequence on one page of recording paper. A color image is formed by transferring the image. Therefore, in FIG. 4, after the Y component image is first transferred to the recording paper (5) -1-, the thermal print head (1) is transferred to the platen roller (6) by a means such as a solenoid (not shown). Pull it away from the capstan roller (7
) and platen roller (6) in the opposite direction, and the recording paper (
Send only 5) one page in the opposite direction and return it to its original position. Thereafter, the platen roller (6) is brought into pressure contact with the thermal print head (1) again, and the M component image is superimposed and transferred onto the Y component image. Similarly, finally convert the C component image to Y
and Il&, and are transferred again onto the images, thus obtaining a color image.

[Problems to be Solved by the Invention] Since the conventional color thermal transfer recording device is configured as described above, when forming a Y component image, an M component image, and a C component image sequentially, each physical It is extremely difficult to align the images, and so-called color shifts are likely to occur. One of the causes of color misalignment is the platen roller (6).
and the pressure contact force of the thermal print head (1). In order to obtain good transfer characteristics, this pressing force requires a large force of about 3 to 6 kg. Ideally, the thermal print head (1) and the thermal transfer paper (2) should slide completely, and the thermal transfer paper (2) and the recording paper (5) should perfectly match the circumferential speed of the platen roller (6). It would be better if they were transported as soon as possible.

In reality, slight slippage occurs between the platen roller (6) and the recording paper (5). Further, due to the large pressure contact force between the platen roller (6) and the thermal print head (1), slippage also occurs between the capstan roller (7) and the recording paper (5). Furthermore, since the pressure contact portions of the platen roller (6) and capstan roller (7) are strained, the effective diameters of these rollers are also extremely unstable, and the effective diameters also vary depending on the ambient temperature. For these reasons, in conventional color thermal transfer recording devices, recording paper (5
) cannot be accurately controlled, and color shift is likely to occur.

This invention was made to solve the above-mentioned problems, and provides a color thermal transfer recording device that can effectively prevent one color shift by accurately measuring and correcting the feeding amount of recording paper. The purpose is to

Means for Solving Problem E] The color thermal transfer recording device according to the present invention includes a thermal print head, a platen roller that presses the thermal transfer paper and the recording paper against the print head, and a thermal transfer paper and a recording paper that are connected to the platen roller via the recording paper. A small roller with a high friction coefficient on the surface to be pressed, a rotary encoder connected to this small roller,
The present invention is characterized by comprising a pulse motor that transports and drives the recording paper, and an electric control circuit that measures the number of output pulses of the rotary encoder and controls the rotation of the pulse motor.

[Function] In this invention, the small roller rotates following the movement of the recording paper without slipping between it and the recording paper, and the rotary encoder controls the movement of the recording paper through the rotation of this small roller. Measure accurately. Then, based on the total 414 results, the electric control circuit controls the number of pulses given to the pulse motor, increases or decreases the rotation angle of the motor, and adjusts the conveyance ψ of the recording paper.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing an embodiment of the invention, and FIG. 2 is a front view thereof. In the figure, (8) is a small roller with 4
Press the platen roller (6) through the recording paper (5) with a weak pressing force.
) is in pressure contact with the The surface of the small roller (9) is specially treated to increase the friction coefficient to prevent slippage between the recording paper (5) and the small roller (9). Further, the length of the small roller (9) is made as short as possible to 20 mm to 30 mm, and its inertia is minimized by adopting a rubber roller structure using an aluminum core (9a).

Further, as shown in Fig. 2, the core (9a) of the small roller (9) is connected to a rotary encoder (10), and the rotation of the small roller (9) is controlled by the rotary encoder (10). Exactly 7111 as a signal
1 is now possible.

Note that the other configurations are the same as those in FIG. 4, so the same parts are given the same reference numerals and the explanation thereof will be omitted.

FIG. 3 is a diagram showing the configuration of an electric control circuit in an embodiment of the present invention, where (14) is a capstan roller (7).
and a pulse motor that drives the platen roller (6),
(12) is the drive circuit of this pulse motor (14), (
11) is a pulse generation circuit that controls the rotation of the pulse motor (14). In addition, (10) is a rotary encoder, and (]3) is a pulse number comparison circuit that compares the output of the pulse generation circuit (11) and the output of the rotary encoder (10), and the output is sent to the pulse generation circuit (11). The number of pulses generated by the pulse generating circuit (11) is controlled.

Next, the operation will be explained. This type of color thermal transfer recording device usually prints one dot line of data on one page, then transports the recording paper (5) and thermal transfer paper (2) by the line pitch, and prints the next one dot line of data. This action is repeated. This line pitch conveyance is often performed by a pulse motor, but in this embodiment as well, by driving the capstan roller (7) with the pulse motor (14) shown in FIG.
5) and the thermal transfer paper (2) are conveyed at each line pitch. In addition, the capstan roller (7) and platen roller (
6), so that the recording paper (5) and the thermal transfer paper (2) are smoothly conveyed in the thermal print head (1) section. Regarding these, please refer to the 4th section.
This is the same as the conventional example shown in the figure.

In this embodiment, the pulse motor (14) is driven by applying a plurality of pulses to the pulse motor (14) to convey by l line pitch. now.

A pulse generation circuit (11) generates a plurality of pulses (here, N
= 4), the pulse motor drive circuit (1
2), the pulse motor (14) rotates in four steps. The amount of conveyance of the recording paper (5) and the thermal transfer paper (2) at this time exactly corresponds to the above-mentioned line pitch.

By the way, in the past, as mentioned above, Capsta 7
0-ra (7), platen roller (6) and recording paper (5)
), causing unstable slippage between the pulse motor (]4
) could not control the conveyance amount of the recording paper (5) alone, but in the embodiment of this invention, the conveyance amount of the recording paper (5) can be controlled by the small roller (9) and the rotary encoder (10). The conveyance I+1 is measured, and the number of pulses generated by the pulse generation circuit (11) is controlled based on the 4 (1 constant result) to increase or decrease the rotation angle of the pulse motor (14), and the recording paper (5) is
Adjust the conveyance amount. This will be explained in detail below.

In Figure 3, the rotary encoder (10) is +i
It is designed to have a resolution of 1/4 of the line pitch of 7f+, and when the recording paper (5) is conveyed reliably by the pulse motor (14), the pulse generation circuit (1
The same number of pulses as those generated in step 1) can be obtained from the rotary encoder (10). The pulse number comparison circuit (13) compares the number of pulses generated by the pulse generation circuit (11) and the number of output pulses of the rotary encoder (lO) for each line pitch (4 pulses), and if there is a difference between the numbers of both pulses, When this happens, a control signal is given to the pulse generation circuit (11) to increase or decrease the number of pulses generated.

For example, when the number of output pulses of the rotary encoder (io) becomes one less than the number of pulses generated by the pulse generation circuit (11), the number of pulses generated per line pitch of the pulse generation circuit (11) is increased from 4 to 5. and record paper (
5) Correct the delay in conveyed goods. Conversely, the number of output pulses of the rotary encoder (10) is higher than that of the pulse generation circuit (
When the number of generated pulses is greater than the number of generated pulses in (11), the number of generated pulses in the pulse generation circuit (11) is decreased. In this way, the number of output pulses of the rotary encoder (page 10) is on average 4 per line pitch, so that no accumulation of errors occurs.

By controlling the conveyance jI) of the recording paper (5) via the rotary encoder (10) as described in I- below, the conveyance of the recording paper (5) is always stable and highly accurate.
Therefore, no color shift occurs.

In the above embodiment, the recording paper (5) is mainly conveyed by the capstan roller (7) and the pinch roller (8).
However, the structure may be such that the platen roller (6) alone is used to transport the paper, or the platen roller and a bin tractor may be used to transport the paper.

Further, in the above embodiment, a rubber roller in which rubber is wrapped around an aluminum core (9a) is shown as a small roller (9), but a metal roller made of a light metal such as aluminum or a plastic roller may also be used. In short, any structure may be used as long as the inertia is small, the surface friction coefficient is large, and the diameter of the roller is stable.

[Effects of the Invention] As described above, according to the present invention, a rotary encoder is connected to a small roller that presses against the platen roller through the recording paper, and the number of output pulses of the rotary encoder is measured to convey the recording paper. Since an electric control circuit is provided to control the rotation of the pulse motor, it is possible to convey the recording paper with extremely high precision, and therefore color shift in reproduced images can be effectively prevented.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of a color thermal transfer recording device according to the present invention, FIG. 2 is a front view thereof, and FIG. 3 is an electrical control circuit for controlling the rotation speed of a pulse motor in an embodiment of the present invention. FIG. 4 is a side view of a conventional color thermal transfer recording device, and FIG. 5 is a diagram showing the structure of thermal transfer paper used in the color thermal transfer recording device. (1)...Thermal print head, (2)...Thermal transfer paper. (5) Recording paper, (B) Platen roller, (
9)...Small roller, (10)...Rotary encoder, (11)...Pulse generation circuit, (12)...
...Pulse motor drive circuit. (13)...Pulse number comparison circuit, (14)...Pulse motor. In addition, in FIG. 1, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A thermal print head, a platen roller that presses the thermal transfer paper and recording paper against this print head, a small roller with a high coefficient of friction on the surface that presses against this platen roller via the recording paper, and is connected to this small roller. A color thermal transfer device comprising: a rotary encoder; a pulse motor that drives the upper recording paper; and an electric control circuit that measures the number of output pulses of the rotary encoder and controls the amount of rotation of the pulse motor. Recording device. (2) The electric control circuit includes a pulse motor drive circuit, a pulse generation circuit that sends pulses to the pulse motor drive circuit, and an output of the pulse generation circuit that compares the output of this pulse generation circuit with the output of the rotary encoder. 2. The color thermal transfer recording apparatus according to claim 1, further comprising a pulse number comparison circuit for controlling the number of pulses.