JP3323290B2 - Thermal transfer printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer printer used as an output device such as a personal computer or a word processor.

[0002]

2. Description of the Related Art Conventionally, a thermal transfer printer has been known as one of output devices used for a personal computer, a word processor and the like.
As disclosed in Japanese Patent Application Publication No. 762 and Japanese Patent Application Laid-Open No. 58-112785, a thermal transfer printer using a stepping motor (pulse motor) as an ink sheet motor or a platen drum motor has been devised. Here, JP-A-59-
JP-A-150762 discloses that the recording sheet and the ink sheet are superimposed on each other by using a single stepping motor capable of rotating forward and backward by superimposing the recording sheet and the ink sheet in a separate path and performing both conveyances by using a single stepping motor capable of reversing the ink sheet. A thermal transfer printer disclosed in US Pat.
Japanese Patent Publication No. 12785 discloses a low-cost thermal transfer printer in which the feed roller and the ink ribbon take-up shaft of the cassette are driven by one pulse motor, and the loading and replacement of the ink ribbon are easy.

[0003]

However, although the above publication describes the use of a stepping motor for driving the platen drum and transporting the ink sheet,
They do not mention software related to stepping motor drive. Generally, a stepping motor is driven by generating a pulse by an interrupt process of a microcomputer in a control unit of the printer.
Normally, there is a plurality of interrupt processes in one control system. Therefore, there is a possibility that another interrupt process may be started while the interrupt process is being performed. As described above, if the priority of the interrupt processing is not taken into consideration, the interrupt processing is performed irregularly, and positioning or the like that requires precision may not be performed well. The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the above-described problems and to provide a thermal transfer printer capable of performing printing with high positional accuracy and without color shift.

[0004]

In order to achieve the above object, the present invention provides a thermal head having a plurality of heating resistors, a color detection sensor, an ink sheet having a plurality of color surfaces, and an ink sheet take-up. Roller and ink sea
Feeding / transporting stepping motor, a platen drum for winding the recording medium, and a platen drum drive
And a stepping motor for each of the ink sheets.
Color detection sensor and ink sheet supply / conveyance for color cueing
In a thermal transfer printer which performs the driving of the platen drum and the ink sheet by at least the pulse generated by the interrupt processing of the microcomputer, the interrupt processing for driving the platen drum is given the highest priority, and the platen drum is driven by the stepping motor .
Following the interrupt processing for each color of the ink sheet
Ink sheet supply / transport stepping for cueing
An interrupt process for driving the motor is prioritized (claim 1).

[0005] Incidentally, in the thermal transfer printer of the present invention,
The driving speed of the previous Symbol platen drum, Hishirushiutsushiji are you faster than Shirushiutsushichu. Further, in the thermal transfer printer of the present invention, the conveying speed of the ink sheet, Hishirushiutsushiji is you faster than Shirushiutsushichu. Furthermore, the thermal transfer printer of the present invention is characterized in that the transport speed of the ink sheet during non-printing is set to the maximum value of the self-starting frequency of the stepping motor (Claim 2 ).

[0006]

In the thermal transfer printer of the present invention, the interrupt processing for driving the platen drum is given the highest priority, and the interrupt processing for driving the platen drum is executed even during the execution of other interrupt processing. Driving is performed, and printing with high positional accuracy and no color shift can be performed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a schematic configuration diagram of a thermal transfer printer showing one embodiment of the present invention. In the drawing, reference numeral 1 denotes a thermal head having a plurality of heating resistors, 2 denotes a color detection sensor,
Is an ink sheet having a plurality of color surfaces, 4 is an ink sheet take-up roller, 5 is a stepping motor for supplying and conveying an ink sheet, 6 is a platen drum for winding a recording medium, and 7 is a stepping motor for driving a platen drum. , 8 is a recording medium, and 9 is a timing belt. Further, a clamp claw for transporting the recording medium 8 is provided at a position a on the surface of the platen drum 6, and a position where the platen drum 6 rotates and a and b coincide with each other is a printing start position. Although not shown, the thermal transfer printer is equipped with a microcomputer, a memory, a counter, a timer, various control circuits for controlling the driving of a motor, a thermal head, and the like, and a control program and a control program stored in the memory. Each part of the printing process is controlled based on the data table.

In FIG. 1, when a printing operation is started, a recording medium 8 is fed from a paper feeding cassette (not shown) by a paper feeding / discharging motor (not shown), and the leading end of the recording medium 6 is clamped by a clamp claw of a platen drum 6. ,
The platen drum 6 is rotated by the stepping motor 7 for driving the platen drum, and the recording medium 8 is wound around the platen drum 6. Then, the clamp part a of the platen drum 6 is rotated to the printing start position indicated by b. At the same time, cueing of each color of the ink sheet 3 is performed by the color detection sensor 2 and the ink sheet supply / transport stepping motor 5. When the clamp portion a of the platen drum 6 reaches the printing start position b and the cueing of the ink sheet 3 is completed, the thermal head 1 is moved to the ink sheet 3.
And then down to the surface of the recording medium to start printing. When the color surface has three colors, this operation is repeated twice later, the clamp by the clamp claws is released, and the recording medium on the platen drum 6 is discharged to a discharge unit (not shown).

FIG. 2 is a flowchart of a control program for performing an interrupt process for driving the platen drum. In this interrupt processing, the present invention is characterized in that first, as shown in FIG. 10, other interrupts (for example, driving of an ink sheet supply / transport stepping motor described later) are prohibited. As a result, no other interrupt is issued until this interrupt routine is completed, so that accurate driving of the platen drum can be performed.

FIG. 3 is a flowchart of a control program for executing an interrupt process for driving a stepping motor 5 for supplying and conveying the ink sheet 3. In this interrupt processing, as shown at 14, only an interrupt for driving the platen drum is permitted, and other interrupts are prohibited. As a result, even when the interruption processing of the ink sheet driving is being performed, the interruption processing for driving the platen drum is started when the set time comes.

FIG. 4 shows the priority of interrupt processing in the printing process control of the thermal transfer printer of the present invention. This priority increases the processing required for accuracy. In the case of the thermal transfer printer of the present invention, the platen drum drive is given top priority in consideration of eliminating color misregistration during printing, and all other interrupts are prohibited as shown at 10 in FIG. Then, priority is given to driving process of the stepping motor 5 for ink sheet feeding and conveying to perform cueing color planes Lee Nkushito 3 to the next. In this interrupt processing,
As shown in FIG. 3, only interrupts for driving the platen drum are permitted, and other interrupts are not permitted. As a result, the ink sheet 3 can be driven next to the platen drum 6 for accurate positioning. In addition to the interrupt processing, the thermal transfer printer according to the present invention has a paper feed / discharge motor drive, L
There are interrupt processing such as ED display and 10 ms timer. However, since these interrupts have a long interrupt cycle and are not required to be so accurate, they are placed below the interrupt processing of the ink sheet supply / transport stepping motor. That is,
Even during the processing of, in FIG. 4, a short interruption processing is performed at the set time.

Next, stepping modes during printing and during non-printing are described.
Data driving will be described. The method is implemented in a sequence program of the printer. For example, a flag is set to set a bit during printing, and clear the bit during non-printing. 2 and 15 in FIG.
Then, the state of the bit of the flag is checked to determine whether or not printing is currently being performed. When the determination is completed, the routine enters a routine for determining the rotation speed of the motor. Generally, the stepping motor is driven by an interrupt process, and one pulse is output by one interrupt process, and the motor advances by one step. That is, the rotation speed of the motor is determined by how long the interrupt process is performed. That is, 1 in FIG.
2, 13 and 16 and 17 in FIG. 3 determine the time period. Therefore, in the thermal transfer printer of the present invention, the time period is set small so that the motor is rotated quickly during non-printing, and the time period is increased during printing.

A second aspect of the present invention is to set the driving speed of the stepping motor 5 for supplying and transporting the ink sheet to the maximum value of the self-starting frequency of the stepping motor. Yes, during printing, rotate at a speed lower than the maximum value of the self-starting frequency. First, an example in which the stepping motor is rotated at a speed higher than the self-starting frequency will be described. To rotate the stepping motor at a speed equal to or higher than the self-starting frequency, it is necessary to slow up and slow down. Hereinafter, an example of the slow-up will be described. As a slow-up method, there is a method of gradually increasing the motor rotation speed by gradually shortening the interruption interval. FIG. 5B shows an example of the data table of the interrupt interval, and FIG.
The value gradually decreases from 1 and the value at time t10 is minimum.
That is, the interruption interval is the shortest and the motor rotation speed is the fastest. A control program for reading a value from this data table and setting an interrupt time is as shown in a flowchart of FIG. In FIG. 5A, the address of TIM_TBL is read at 18, and an offset value is added to the address. And as shown in 19,
The content of the address to which the offset value has been added is put into A3, added to the current time, and an interrupt is set. The offset value is controlled as indicated by 20 so as not to exceed the number of data in the table. In this way, you can slow down,
The motor can be rotated at a speed higher than the self-starting frequency. However, in this method, the program becomes complicated as compared with the control shown in FIG. 3, and there is a possibility that other (lower) interrupt processing may be affected.

Therefore, the gist of the present invention is to rotate the motor as fast as possible without causing the motor to lose synchronism.
It rotates at the maximum value of the self-starting frequency. As described above, the speed of the motor is determined by 17 in FIG. 3, and in the present invention, by appropriately determining A3 of 17, the frequency of the pulse generated in the interrupt processing becomes equal to the maximum value of the self-starting frequency. For example, now the maximum value of the motor's self-starting frequency is
If it is 5000 PPS, one cycle is 200 μsec. I mean
If an interrupt occurs every 200 μs, a pulse of 5000 PPS is generated and the motor can be driven. As a method, read the timer value, add 200μsec to the value, and when the timer value becomes equal to that value, interrupt it again,
Repeat it. In this case, A3 has 200 μsec.
5 can be omitted, and processes such as 18, 19, and 20 in FIG. 5 can be omitted, and the program can be simplified. Although the embodiment of the present invention has been described above, this is an example, and the present invention is not limited to this, and various modifications are possible.

[0015]

As described above, in the thermal transfer printer according to the first aspect, the interrupt processing for driving the platen drum is given the highest priority. Therefore, the interrupt for driving the platen drum can be performed even while other interrupt processing is being executed. Since the process is executed, accurate drum driving is performed at a constant speed, and printing with high positional accuracy and no color shift can be performed.

[0016] Then, in the thermal transfer printer according to claim 1, subsequent to the interrupt processing for driving the platen drum, performs the color beginning of the ink sheet Inkushi
By giving priority to the interrupt processing for driving the stepping motor for feeding and transporting the ink, the cueing of each color of the ink sheet can be accurately performed.

In the above-mentioned thermal transfer printer, by setting the driving speed of the platen drum to be higher during non-printing than during printing, it is possible to quickly perform sheet feeding / discharging and detection of the printing start position. Time can be reduced.

In the above thermal transfer printer, the ink sheet is conveyed at a higher speed during non-printing than during printing, so that cueing of each color of the ink sheet can be performed quickly. Can be shortened.

In the thermal transfer printer according to the second aspect of the invention, by setting the transport speed of the ink sheet during non-printing to the maximum value of the self-starting frequency of the stepping motor, the interrupt processing program can be simplified and the execution time can be reduced. In addition, the ink sheet can be conveyed at a high speed with little influence on other processes.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a thermal transfer printer showing one embodiment of the present invention.

FIG. 2 is a flowchart illustrating an example of a control program for performing an interrupt process for driving a platen drum.

FIG. 3 is a flowchart illustrating an example of a control program for performing an interrupt process for driving an ink sheet motor.

FIG. 4 is a diagram showing a list of interrupt processing priorities;

FIG. 5A is a flowchart illustrating another example (slow-up) of a control program for performing an interrupt process for driving an ink sheet motor, and FIG. 5B is a diagram illustrating a data table of interrupt intervals.

[Explanation of symbols]

 1: Thermal head 2: Color detection sensor 3: Ink sheet 4: Ink sheet take-up roller 5: Ink sheet supply / transport stepping motor 6: Platen drum 7: Platen drum drive stepping motor 8: Recording medium 9: Timing belt

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 29/38 B41J 2/325 B41J 11/42 B41J 17/02

Claims (2)

(57) [Claims] 1. A thermal head having a plurality of heating resistors, a color detection sensor, an ink sheet having a plurality of color surfaces, an ink sheet take-up roller, and an ink sheet
A stepping motor for supplying / transporting, a platen drum for winding the recording medium, and a driving mechanism for the platen drum .
Stepping motor for each color of the ink sheet
For color detection sensor and ink sheet supply / transport
In a thermal transfer printer in which a stepping motor is used and at least platen drum driving and ink sheet driving are performed by pulses generated by microcomputer interrupt processing, interrupt processing for driving the platen drum is given top priority and the platen drum is driven.
For each color head of the ink sheet,
Stepping module for feeding and transporting ink sheet
A thermal transfer printer characterized by giving priority to interrupt processing for driving data . 2. The thermal transfer printer according to claim 1, wherein
Stepping the transport speed of the ink sheet when not printing
A thermal transfer printer wherein the self-starting frequency of the motor is set to the maximum value .