JP2810806B2 - Print timing generation circuit in serial 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 print timing generating circuit for generating a print timing from an output of a slit encoder attached to a drive motor for moving a print head in a spacing direction in a serial printer.

[0002]

2. Description of the Related Art Conventionally, in a serial printer, a driving motor for driving a carriage having a print head is
A slit disk and an encoder are attached, and the phase edge of the slit is output through the encoder in accordance with the rotation of the drive motor, and the print timing is generated by counting the output. FIG. 4 is a control block diagram showing a conventional serial printer for generating such print timing, and FIG. 5 is a schematic structural diagram showing a main part of the serial printer.

In FIG. 4, a control section 1 controls the operation of the entire printer. The ROM 2 stores a control program for performing operation control. The RAM 3 is for temporarily storing data. Motor drive circuit 4
Is a circuit for driving a DC servo motor 5 for driving the carriage. The DC servo motor 5 drives the carriage 6 shown in FIG. 5 to space the print head 7 mounted on the carriage 6 via the timing belt 8. In the directions (the directions of arrows A and B shown in FIG. 5). The DC servomotor 5 is also provided with a slit disk 9 and a two-phase encoder 10 with the slit disk 9 interposed therebetween. As the slit disk 9, a disk having slits at 1/360 "intervals is used.

The speed detection / interruption generation circuit 11 receives the output of the encoder 10, detects the edge thereof, and counts the time between the edges using a basic clock. The basic clock is input from the control unit 1. The position counter 12 counts the number of edges of the encoder output counted by the speed detection / interruption generation circuit 11 and detects the print start position specified by the control unit 1. The print head drive circuit 13 is for driving the print head 6.

Next, the operation will be described with reference to a time chart shown in FIG.

[0006] The motor drive circuit 4 according to the instruction of the control unit 1
When the DC servo motor 5 rotates, the carriage 6 and the print head 7 move in the direction of the arrow A or B via the timing belt 8 shown in FIG. At the same time, the slit disk 9 also rotates, and the encoder 10 outputs φA, φB shown in FIG.
Are output. The encoder outputs φA and φB have a phase difference of 90 ° from each other as shown in FIG. The encoder outputs φA and φB are sent to the speed detection / interruption generating circuit 11, where the edges of the encoder outputs φA and φB are detected. The edge interval detected here is 1/360 ″ for the slit disk 9 shown in FIG.
Since the slits are provided at intervals, the speed is 1/360 ″. The basic clock is input from the control unit 1 to the speed detection / interruption generation circuit 11 as described above, and is 1/36 ″.
The time between 0 ″ edges is counted by the basic clock.
(T ₁ , T ₂ , T ₃ , T ₄ , T ₅ shown in FIG. 6) The number of counted clocks (T ₁ , T ₂ , T _3, ...) Is not necessarily the same between the edges (the cause is an encoder). May be caused due to characteristic variations or mounting errors, etc.). Therefore, every time the 1/360 ″ edge is detected four times, the speed detection / interruption generation circuit 11 averages the count numbers of the four times immediately before that, and adjusts the timing corresponding to the averaged value (Tave) to the shaped edge. The shaped 1/360 "timing is sent to the print head drive circuit 13 and used as a print timing.

When a slit disk with a 1/360 "interval is used, for example, print timing at a 1/90" interval is generated by four times of edge output, and a 90 DPI (DotPer) is generated.
Inch) printing is realized. In particular, domestic printers that print kanji are based on the 180 DPI system.
/ 360 "spacing slit disks are used.
Overseas printers often print only alphanumeric characters,
The 120 DPI system has become mainstream.

[0008] Such a 120 DPI printer is 1 /
It uses slit discs with 480 "spacing. And recently, serial printers for domestic use (180 DPI system)
Also, a printer capable of 120 DPI printing has been required.

[0009]

However, for example, in the case of realizing 120 DPI printing with a 180 DPI printer, a printing timing of 240 DPI or the like cannot be generated with a slit disk at a 1/360 ″ interval.
In order to realize this, a new slit disk with a 1/720 ″ interval may be used. However, such a disk having a large number of slits is extremely difficult to manufacture because the size of the disk itself is limited. Difficult and difficult to use.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a circuit for generating print timings of different DPI systems, thereby eliminating the need for a new slit disk having a large number of slits. Another object of the present invention is to provide an excellent print timing generation circuit which can generate print timings different from each other in DPI system and which has versatility.

[0011]

According to the present invention, there is provided a print timing generating circuit for counting the number of basic clocks between the edge outputs of a slit encoder attached to a drive motor to generate print timing. A digital filter for detecting a numerical value between edge outputs counted by the number of basic clocks a plurality of times, averaging and outputting the numerical value, and dividing means for dividing the averaged numerical value according to the slit interval of the slit disk. And timing generating means for counting the divided numerical values and generating print timing.

[0012]

The number of clocks counted between the edge outputs of the slit encoder is averaged by a digital filter. Next, the averaged numerical value is divided by the dividing means according to the slit interval of the slit disk. Then, the divided numerical values are counted to generate a print timing. Therefore, the state becomes the same as the case where a slit disk having a larger number of slits than the actually used slit disk is used, and it is possible to cope with printing of different DPI systems.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. Elements common to the drawings are assigned the same reference numerals.

FIG. 1 is a block diagram showing an embodiment according to the present invention, and FIG. 2 is a circuit diagram showing a print timing generating circuit of the embodiment.

In FIG. 1, a control unit 21 comprises a CPU, controls the operation of the entire apparatus, and generates a basic clock. The ROM 2, RAM 3, and motor drive circuit 4 are the same as in the conventional example. The DC servo motor 5 also moves the carriage on which the print head 7 is mounted in the spacing direction as shown in FIG. 1/36 for DC servo motor 5
A slit disk 9 at 0 ″ intervals is mounted, and an encoder 10 is mounted with the slit disk 9 interposed therebetween.

The speed detection / interruption generation circuit 22 receives the output of the encoder 10, detects the edge thereof, and counts the time between the edges using a basic clock. The speed detection / interruption generating circuit 22 has a built-in digital filter (not shown). The position counter 23 counts the number of 1/360 "edge outputs and outputs a print timing generation circuit 24.
Output to

The print timing generation circuit 24 detects the speed /
A new print timing is generated based on the count value counted by the interrupt generation circuit 22. As shown in FIG. 2, mainly flip-flops 25, 26, 27, counters 28, 29, a synchronous counter 30, and the like are used. Be composed. Specifically, <74LS171> or the like is used as the flip-flops 25, 26, and 27.
<74LS163> or the like is used as 8, 29, 30. The output signal 31 from the position counter 23, the digital filter value 32 from the speed detection / interruption generation circuit 22, the reset signal 33 and the basic clock signal 34 from the control unit 21 are input to the print timing generation circuit 24. The output is a flip-flop 27
From the print timing signal 35
Is output to

Next, the operation of generating print timing according to the present embodiment will be further described with reference to a time chart shown in FIG.

When the DC servo motor 5 is rotated by the motor drive circuit 4 in accordance with an instruction from the control unit 21, the carriage 6 and the print head 7 shown in FIG. 5 move in the spacing direction. At the same time, the slit disk 9 rotates, and the encoder 10 outputs two-phase slit detection signals of φA and φB. Encoder outputs φA and φB as in the conventional example
Have a phase difference of 90 ° from each other. This output φA,
φB is sent to the speed detection / interrupt generation circuit 22. The digital filter in the speed detection / interrupt generation circuit 22 is 1/3
60 "detects the distance of the edge to count the reference clock between the edges. Where digital filter instead of the actual value obtained by counting the clock, and outputs the corrected value as the count value. N ₁ shown in FIG. 3, n ₂ ... are modified value. Incidentally, n _1, n ₂ ... are each different possible values.

Further, the speed detection / interruption generation circuit 22
When an edge at 60 "intervals is detected, the detection signal is sent to the position counter 23. The position counter 2
3 generates a 1/90 "timing based on this signal and sends a 1/90" timing signal to the print timing generation circuit 24.

The count value counted by the digital filter of the speed detection / interruption generation circuit 22 is input to the counters 28 and 29 of the print timing generation circuit 24. At this time, by not connecting the lower one bit (bo), The input value is 1/2 of the count value. And the above 1
At the timing of / 90 ″, the count value (n ₁ , n ₂ ...)
Is loaded into the counters 28 and 29.
1/90 is loading 1/2 (n _1/2) of the counted count value immediately before the timing of the "counter 29 counts this basic clock. Then put out the carry output of the counter 28 Then, the print timing 35 is output from the flip-flop 27. The carry output again causes the counter 28,
Load 29 and continue counting. Doing this twice, the count value by the digital filter is coming timing of the next 1/360 "is updated, n _2/2
Is loaded to the counters 28 and 29. In this way, half the time of the latest count value is counted, and a print timing 35 of 1/720 ″ is output each time. The number of carry outputs of the counter 28 is counted by the synchronous counter 30, and At the time of counting seven times, a count stop signal is sent to the counters 28 and 29, and the counter 2
8 and 29 stop counting. In this state, the print timing signal 35 is output by the 1/90 "timing signal 32 input from the position counter 23. The synchronous counter 3 is output by the 1/90" timing signal 32.
0 are reset and the count value by the next digital filter to the counter 28,29 (n _5/2) is loaded. As a result, a 1/720 "print timing 35 is output again. The 1/720" timing output is not a pulse output but a level output as shown in FIG. 3, thereby preventing errors due to noise.

As described above, in this embodiment, 1/7
Since the synchronization between the 20 "print timing and the edges of the encoder outputs φA and φB is set for every 1/90”, even if a variation in the carriage speed occurs, the deviation of the 1/720 ”timing output does not accumulate. Since the 1/720 "print timing is always generated using the latest digital filter count value, even if the carriage speed fluctuates, an accurate 1/72" print timing can be obtained.
Timing at 0 ″ intervals can be generated.

In the above embodiment, a 1/360 "slit disk is used to obtain a 1/720" print timing.
A 0 "slit disk may be used, and the count value between slit detection edges may be divided into three to obtain 1/720" print timing.

In the above embodiment, the impact printer is described as a serial printer. However, the present invention is not limited to this, and can be applied to a non-impact printer such as an ink jet printer.

[0025]

As described above in detail, according to the present invention, it is possible to generate different print timings of the DPI system without newly requiring a slit disk having a large number of slits. That is, since print timings at 1/720 ″ intervals can be generated, the 180 DPI system and the 120 DPI
Both types of printing can be performed, and the versatility is excellent.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment according to the present invention.

FIG. 2 is a circuit diagram showing a print timing generation circuit according to the embodiment;

FIG. 3 is a time chart showing the operation of the embodiment.

FIG. 4 is a control block diagram showing a conventional serial printer.

FIG. 5 is a schematic structural view showing a main part of the serial printer.

FIG. 6 is a time chart showing a print timing generation operation of a conventional example.

[Explanation of symbols]

 Reference Signs List 5 DC servo motor 7 Print head 9 Slit disk 10 Encoder 21 Control unit 22 Speed detection / interruption generation circuit 23 Position counter 24 Print timing generation circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/51 B41J 19/18

Claims (1)

(57) [Claims] 1. A print timing generation circuit which counts the interval between the edge outputs of a slit encoder attached to a drive motor with the number of basic clocks to generate print timing, wherein the edge between the edge outputs of the slit encoder is counted with the number of basic clocks. A digital filter that detects a numerical value between outputs a plurality of times, averages and outputs the numerical value, a dividing unit that divides the averaged numerical value according to a slit interval of a slit disk, and counts the divided numerical value. A print timing generation circuit for a serial printer, comprising: a timing generation means for generating print timing.