JPH0544348B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] When printing with a thermal printer, it is necessary to bring the thermal head into close contact with the paper by an approach operation, either directly or via a ribbon. In order to prevent the printer from getting stuck, the approach operation is controlled so that it is always completed in the vicinity of the print start position, regardless of the print speed.

[Industrial application field]

The present invention relates to a thermal printer, and more particularly to a thermal printer that prevents the thermal head from getting caught on the edge of the paper when performing approach control to bring the thermal head into close contact with the paper.

Thermal printers include a color-forming type that heats a heating element in a thermal head and uses thermal paper that develops color by this heating, and a color-forming type that uses heat from the thermal head to heat a ribbon to melt the heat-melting ink and transfer it onto the paper. There is also a heat transfer type.

By the way, regardless of the type of thermal printer, when printing, it is necessary to transfer the heat from the heating element of the thermal head to the paper or ribbon, so when printing, the thermal head must be attached to the paper on the platen. Approach control is performed to bring the thermal head into close contact with the paper either directly or via a ribbon, and escape control is performed to evacuate the thermal head from above the paper so that the thermal head or ribbon does not rub the paper during line feed or carriage return.

Furthermore, since thermal printers print serially, the thermal head is moved by space control. Therefore, when starting printing, approach control is used to move the thermal head toward the platen, and space control is used to position the thermal head at the printing start position, but at this time, the thermal head must not get caught on the edge of the paper. It is necessary.

[Conventional technology]

Conventionally, the approach operation of the thermal head was started before or simultaneously with the activation of the space motor. Therefore, printing is started some time after the approach operation is completed.

FIG. 4 is a diagram illustrating a conventional approach operation.

25 is a plantain, and 26 is a sheet of paper, such as a postcard, set on the platen 25. As described above, the thermal head 27 starts approaching for printing, and at the same time the space motor is activated.

Therefore, the thermal head 27 moves obliquely toward the platen 25 at an angle determined by the approach speed and the space speed, as shown by arrow E, and comes into close contact with the platen 25 at the position of the thermal head 28.

Thermal head 28 after the approach operation has finished
moves in the direction of arrow F with the space movement,
Printing starts when the printing start position is reached, so
The heating element is heated.

[Problem that the invention seeks to solve]

As mentioned above, conventionally, regardless of the printing start position,
Since the approach operation is performed, there is a problem in that the thermal head 28 gets caught on the edge of the paper 26 depending on the set position of the paper 26, especially when printing on thick paper such as a postcard.

Furthermore, in printers that have multiple printing speeds, even if control is performed so that the approach operation is completed immediately before printing starts when printing at the highest speed, when switching to a slower printing speed, the space speed is slow,
Since the approach time is the same, there is the same problem of the thermal head reaching the platen faster and catching on the edge of the paper.

In view of these problems, the present invention determines the approach start position from the space speed and print start position, so that the approach operation of the thermal head always ends immediately before printing starts, regardless of the print speed. It is.

[Means for solving problems]

FIG. 1 is a block diagram of the principle of the present invention.

1 is a host device such as a word processor or a personal computer; 2 is a display section of the host device 1; 3 is a main body of the host device; and 4 is a keyboard for inputting commands and data into the main body 3.

5 is a thermal printer that prints characters etc. under the control of the host device 1; 6 is a control means that detects the print start position from the print data sent by the host device and determines the approach start timing from the printing speed; 7 is the control means This is an approach means for driving a pulse motor in an open loop according to the instruction No. 6.

The control means 6 of the thermal printer 5 detects the printing start position from the printing data given from the host device 1, starts the spacing operation, and then determines the timing of starting the approach of the thermal head according to the printing speed. The configuration is such that an instruction to drive the pulse motor is sent to the approach means 7, and the approach operation is completed in a certain period of time.

[Effect]

With the above configuration, the control means of the thermal printer determines the approach start timing of the thermal head according to the printing speed, and the approach means drives the pulse motor in an open loop based on this timing to perform the approach in a fixed time. In order to complete the approach operation, it is possible to always avoid the edge of the paper and complete the approach operation just before the print start position.

〔Example〕

FIG. 2 is a block diagram of a circuit showing one embodiment of the present invention.

The processor 10 reads a program from the ROM 11 and operates. When print data is sent from a host device such as a word processor via the interface circuit 13, the processor 10 stores it in the RAM.
14 and then read out, and the print start position is extracted from the print data.

Here, the processor 10 calculates the amount of movement of the thermal head 16 from the printing start position and the retracted position of the thermal head 16, and determines the approach start timing from the printing speed and the time required for the approach.

The processor 10 drives the space motor 20 via the space control circuit 19 to drive the thermal head 1.
At the same time, the pulse motor 22 is driven via the approach/escape control circuit 21 at the above timing, and the thermal head 16 is moved to the printing position.
approach.

FIG. 3 is a diagram illustrating the approach operation of the present invention.

For example, FIG. 3a shows a case where the printing speed is 80 characters/second, and FIG. 3b shows a case where the printing speed is 40 characters/second.

In FIG. 3a, the thermal head 27 starts a space motion by the space motor 20, moves in the direction of arrow A, and when it reaches the position of the thermal head 29, the pulse motor 22 starts at the timing determined by the processor 10. , starts approaching in the direction of the platen 25, moves in the direction of arrow B by combining with the space motion, completes the approach motion at the position of the thermal head 30, and comes into close contact with the paper 26 just before the printing start position. .

There is a margin between the print start position of the paper 26 and the edge of the paper 26, and if the thermal head 30 comes into close contact with the paper 26 just before the print start position, the thermal head 30 will not catch on the edge of the paper 26.

In FIG. 3b, the thermal head 27 starts a space operation by the space motor 20, moves in the direction of arrow C, and when it reaches the position of the thermal head 31, the pulse motor 22 starts to move at the timing determined by the processor 10. , starts approaching in the direction of the platen 25, moves in the direction of arrow D by combining with the space motion, completes the approach motion at the position of the thermal head 32, and comes into close contact with the paper 26 just before the printing start position. .

Here, in the same manner as above, the thermal head 32
will not get caught on the edges of the paper 26.

The difference between Fig. 3 a and b is that the printing speed, that is, the space speed, is twice as fast in Fig. 3 a as in Fig. 3 b, but
Since the approach time is always constant because the pulse motor 22 is driven in an open loop, the positions of the thermal heads 29 and 31 are different.
This position can be easily calculated from the print start position on the paper 26.

The processor 10 extracts a character code from the print data, reads out a character pattern corresponding to the character code from the character generation circuit 12, and outputs the character pattern to the head control circuit 1.
5 and then sent to a thermal head 16 to heat a heating element and perform printing.

When the processor 10 extracts the line feed code from the print data, the approach/escape control circuit 2
1, the pulse motor 22 is driven to escape the thermal head 16, and the line feed motor 18 is driven via the line feed control circuit 17 to feed the paper.

〔Effect of the invention〕

As explained above, the present invention can prevent the thermal head from getting caught on the edge of the paper.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention, FIG. 3 is a diagram explaining the approach operation of the present invention, and FIG. 4 is a conventional approach operation. FIG. In the figure, 1... host device, 2... display section,
3... Main body, 4... Keyboard, 5... Thermal printer, 6... Control means, 7... Approach means, 10... Processor, 11... ROM, 12
... Character generation circuit, 13 ... Interface circuit, 14 ... RAM, 15 ... Head control circuit,
16... Thermal head, 17... Line feed control circuit, 18... Line feed motor, 19... Space control circuit, 20... Space motor, 21... Approach/escape control circuit, 22... Pulse motor, 25... Platen, 26...paper.

Claims (1)

[Claims] 1. A thermal head is moved along a platen at a speed corresponding to each of a plurality of printing speeds, and the thermal head is moved by an approach operation,
A thermal printer 5 that prints by moving it from a retracted position toward the platen and bringing it into close contact with paper directly or via a ribbon, and detecting a print start position from print data given from a host device 1; a control means 6 for determining the timing of starting the approach operation based on a predetermined retracted position of the thermal head, the printing speed, and the time necessary for the approach operation; and an approach means 7 for completing the approach operation in a timely manner, and as the printing speed becomes slower, the approach operation start timing is delayed, and the thermal head is brought into close contact with the paper immediately before the printing start position. thermal printer.