JPS6120470A - Heat sensitive recording device - Google Patents

Abstract

PURPOSE:To reduce the generation of blank part between print dots immediately before and after the acceleration of carrying speed of a recording paper by increasing a speed for the quantity of carrying when the quantity of carrying of tge recording paper becomes smaller then expected quantity of carrying, and at the same time, increasing energy applied to a thermal head. CONSTITUTION:A quantity of carrying detection signal 22 outputted from a quantity of carrying detector 21 is compared with a reference signal 24 corresponding to expected carrying speed in a correction operating circuit 23, and the difference is derived. When the quantity of carrying is decreased, the correction operating circuit 23 supplies a correction signal 25 for the applied number of pulses and a correction signal 26 for the applied pulse width corresponding to the decrement to a pulse motor controlling circuit 27 and a thermal head controlling circuit 27 and a thermal head controlling circuit 28 respectively. The pulse motor controlling circuit 27 accelerates a pulse motor 31 for rotating a driving roller 6 by a pulse motor driving circuit 30. The thermal head contrlling circuit 28 supplies a pulse signal 32 obtainec by adding pulse width corresponding to the content of the correction signal 26 for applied pulse width to expected pulse width to a thermal head driving circuit 34 according to print data 33.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to a thermal recording device, and in particular, when the conveyance amount of recording paper is corrected, the applied energy of the thermal head is also corrected accordingly. The present invention relates to a thermal recording device that can improve printing quality.

``Prior art'' For example, in a transfer-type thermal recording device, an ink donor film with ink coated on one side of base paper is overlapped with recording paper, and the base paper side of the ink donor film is selectively heated by a thermal head. It has become. The ink fluidized or sublimated by this heating is transferred to the recording paper, thereby recording image information.

FIG. 4 shows an example of such a conventional transfer type thermal recording apparatus.

This recording apparatus is equipped with a long ink donor film 1 wound around a supply roll 2. The ink donor film 1 fed out from the supply roll 2 is
After passing through the guide roller 3, between the thermal head 4 and the back roller 5, between the drive roller 6 and the vinyl roller, and through the guide roller 8, it is wound onto a take-up roll 9. Drive roller 6 and take-up roll 9 are configured to receive the driving force of pulse motor 10 via timing belt 11.12, pulley 13.14, etc., and are rotated in the direction of the arrow.

Now, print paper 1 from the paper feed tray (not shown) of this recording device.
5 is sent out, transported in the six directions of the arrow, and reaches the vicinity of the thermal head 4. Then, a sensor (not shown) detects this, the pulse motor 10 starts driving, and the drive roller 6 and take-up roll 9 are rotated in the directions of the arrows.

As a result, the ink donor film 1 is conveyed in the direction of arrow B, and the recording paper 15 passes between the thermal head 4 and the back roller 5 while being overlapped therewith. At this time, the thermal head is driven according to the print data, selectively heating the ink donor film 1, and thermal transfer recording is performed. After recording is completed, the recording paper 15 is peeled off from the ink donor film 1, conveyed in the direction of arrow C, and discharged to a discharge tray (not shown).

By the way, in such a recording device, the printing pitch in the main scanning direction is determined by the density of the linear heat generating part of the thermal head 4, and the printing pitch in the sub-scanning direction is determined by the density of the ink donor film 1 and the recording paper 15 superimposed thereon. It will be determined by the conveyance speed.

For example, the density of the heat generating part of the thermal head 4 is set to 300 S.
When P I (Spot Per Inch) and the conveyance speed of the recording paper 15 is approximately 85 μm per line, the printing pitches P1 and P2 in the main scanning direction and the sub-scanning direction are as shown in FIG. Both are approximately 85 μm. At this time, the size D of the print dot in the sub-scanning direction is 8.
If it is about 5 μm, printing as shown by the circle in the figure will be performed.

However, in such a recording device, for example, the surface of the drive roller 6, which is generally made of rubber, deteriorates over time, or
Alternatively, if dirt, dust, etc. adhere to the same surface, or if the load on the ink donor film transport system fluctuates, local slip may occur between the drive roller 6 and the ink donor film 1.

Assuming that such a slip occurs and the conveyance amount of the recording paper 15 decreases, for example, by about 10 μm, as shown in FIG.
3=only about 75 μm can be conveyed. As a result, the subsequent printing location M in the sub-scanning direction is shifted from the intended printing location N, resulting in a decrease in printing quality. In particular, when performing multicolor recording using a plurality of ink donor films containing different inks, if the printing locations in the sub-scanning direction in each recording section are different from each other, color shift occurs and print quality is significantly degraded.

In order to solve this problem, the conveyance amount of the recording paper 15 is detected, and when a slip occurs between the drive roller 6 and the ink donor film 1, the conveyance speed of the recording paper 15 is adjusted accordingly. A recording apparatus has been proposed in which the printing speed is increased and thereby the printing location in the sub-scanning direction is corrected to the desired printing location.

In such a recording device, for example, as shown in FIG.
The place where the recording paper 15 should be conveyed by P2 - about 85 μm is P3.
- If the recording paper 15 can only be transported by about 75 μm, this is detected and the transport speed of the recording paper 15 is increased by the difference (P2P3=10 μm). By this speed increase, the recording paper 15 is conveyed by P, - about 95 μm, so that the subsequent printing location in the sub-scanning direction becomes the intended printing location.

However, in such a recording device, the interval between the printing points immediately after and immediately after increasing the conveyance speed of the recording paper 15 is P4.
(approximately 95 .mu.m in the above example), which is larger than the regular pitch P2 - approximately 85 .mu.m. For this reason, in such a recording device, a blank space is generated between the printed dots, as shown by the reference numeral 16 in FIG. 7, for example.
This appears as white sushi, and print quality deteriorates due to a new cause.

"Problems to be Solved by the Invention" The present invention has been made in view of the above circumstances, and aims to minimize the occurrence of blank areas between printed dots immediately before and immediately after increasing the conveyance speed of recording paper. It is an object of the present invention to provide a heat-sensitive recording device that can reduce the amount of heat generated.

"Means for Solving the Problems" The present invention includes a thermal head that selectively generates heat according to print data, a transport mechanism for transporting recording paper at a constant speed to the thermal head, and a recording paper. A conveyance amount detection means for detecting the conveyance amount of paper, and a conveyance speed for the recording paper by the conveyance mechanism when the conveyance amount of the recording paper decreases from the expected conveyance amount based on the detection result of this conveyance amount detection means. and applied energy correction that increases the energy applied to the thermal head when the conveyance amount of the recording paper decreases from the expected conveyance amount based on the detection result of the conveyance amount detection means. The recording paper is equipped with means for increasing the size of the printing dots immediately after increasing the conveyance speed of the recording paper, thereby making it possible to fill in blank areas.

"Example" The present invention will be described in detail below with reference to Examples.

FIG. 1 shows the main parts of the electric circuit of a transfer type thermal recording device to which an embodiment of the present invention is applied.

This recording apparatus includes a conveyance amount detector 21 that can detect the conveyance amount of recording paper. The conveyance amount detector 21 includes, for example, an optical sensor that can continuously detect the leading edge or the trailing edge of the recording paper being conveyed, and can determine the conveyance amount of the recording paper based on the detection result. It has become.

A carry amount detection signal 22 output from the carry amount detector 21 is supplied to a correction amount calculation circuit 23. Correction amount calculation circuit 23
compares the supplied fine feed amount detection signal 22 with a reference signal 24 corresponding to the intended conveyance speed, and determines the difference.

Now, slippage has occurred between the drive roller and the ink donor film, and as shown in FIG.
Assume that the amount of conveyance is reduced by about 10 μm, and the conveyance amount is reduced by about 10 μm, instead of being conveyed by about 85 μm. Then, the correction amount calculation circuit 23 generates an applied pulse number correction signal 25 and an applied pulse width correction signal 2 corresponding to this reduction amount.
6 is supplied to the pulse motor control circuit 27 and the thermal head control circuit 28, respectively.

The pulse motor control circuit 27 receives an applied pulse number correction signal 2.
5, the number of pulses corresponding to the content of this signal is changed to the desired number of pulses (the ink donor film is
Pulse signal 29 in addition to the number of pulses required for transport)
is supplied to the pulse motor drive circuit 30. As a result, the pulse motor 31 for rotating the drive roller is driven at an increased speed, and the ink donor film is conveyed by P = approximately 95 μm together with the recording paper superimposed thereon.

On the other hand, upon receiving the applied pulse width correction signal 26, the thermal head control circuit 28 changes the pulse width corresponding to the content of this signal to the desired pulse width (the size of the printed dot in the sub-scanning direction is approximately 85 μm). A pulse signal 32 in which the pulse width required for At this time, if the characteristics of the thermal head 35 are, for example, as shown by the solid line in FIG.
When m5, it becomes 105 μm. Therefore, if the pulse width of the pulse signal 32 is set to 0.85 m5, which is the expected pulse width of 0.7 ms plus 0.15 m5, printing will be performed as shown by the relatively large circle in Figure 2. become.

In this way, in this recording apparatus, even if the interval between the printing points immediately before and after increasing the conveyance speed of the recording paper is P, which is larger than the regular pitch P2, there will be no difference between the printed dots as shown in FIG. A blank area as shown by 16 does not occur.

The characteristics of the thermal head 35 are thermal head 3゛5.
The temperature depends on the temperature of the substrate and the temperature of the atmosphere, and when these temperatures are high to a certain extent, they are shown by the dashed-dotted line in FIG. 3, and when they are low, they are shown by the dashed-double-dotted line.

Therefore, this temperature information 36 is supplied to the thermal head control circuit 28, and the thermal head 35 is
By correcting the width of the pulse applied to the image, it becomes possible to perform better printing. Furthermore, the applied voltage may be corrected instead of the applied pulse width.

Further, in the above embodiment, the case where the present invention is applied to a transfer-type thermal recording device has been explained, but a direct-type thermal recording device that directly records by using thermal paper as a recording paper without using an ink donor film. Of course, it also applies to scales.

"Effects of the Invention" As explained above, according to the present invention, it is possible to minimize the occurrence of blank areas between printed dots immediately after and immediately after increasing the conveyance speed of the recording paper, so that white sushi is (The print quality is improved.)

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main parts of the electric circuit of a transfer type thermal recording device to which an embodiment of the present invention is applied, FIG. 2 is a diagram shown to explain printing by the device, and FIG. 3 is the same diagram. FIG. 4 is a schematic configuration diagram showing an example of a conventional transfer type thermal recording device; FIGS. 5 and 6 are diagrams showing the printing by the device, respectively; FIG. 7 is a diagram for explaining printing by another conventional transfer type thermal recording device. 21... Conveyance amount detector, 23... Correction amount calculation circuit, 27... Pulse motor control circuit, 28...
- Thermal head control circuit, 30... Pulse motor uioom, 31... Pulse motor, 34... Thermal head drive circuit, 35...
...Thermal head. Applicant Dai Fuji Xerox Co., Ltd. Representative Patent Attorney Ume Yamauchi Bacteria 1 Figure 2 Applied pulse width (msec) Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] A thermal head that selectively generates heat according to print data, a conveyance mechanism for conveying recording paper at a constant speed with respect to the thermal head, a conveyance amount detection means for detecting the conveyance amount of the recording paper; a conveyance amount correction means for increasing the conveyance speed of the recording paper by the conveyance mechanism when the conveyance amount of the recording paper decreases from a desired conveyance amount based on a detection result of the conveyance amount detection means; and a conveyance amount detection means. 1. A thermal recording apparatus comprising applied energy correction means for increasing the energy applied to the thermal head when the conveyance amount of the recording paper decreases from the expected conveyance amount based on the detection result.