JPS6324108A - Shuttle position sensor - Google Patents

Abstract

PURPOSE:To eliminate the influence of variation in the light emission quantity of a light emitting element by generating a threshold value for obtaining an edge detection signal from the output of a light receiving element for pint clock detection. CONSTITUTION:The area of a hole for edge detection is equalized to the total area of holes for print clock detection. Consequently, light receiving elements 5a and 5b are irradiated almost equally in the quantity of light when the holes of masks 22 and 4 meet each other. A print clock waveform detected by the light receiving element 5a has its DC component cut off by a capacitor C1 and the remaining variation component VHP is compared with the threshold value by a comparing circuit 20. An edge waveform detected by a light receiving element 5b is compared by a comparing circuit 21 with a threshold value including the DC component of the print clock waveform. The circuit 21 outputs its result edge detection signal.

Description

[Detailed Description of the Invention] [Summary] In the shuttle position sensor that detects the position of the shuttle, in order to avoid erroneously detecting the shuttle position due to fluctuations in the amount of light emitted from the light emitting element due to temperature fluctuations, a light receiving system for detecting the print clock is used. A threshold value for obtaining an edge detection signal was created from the output of the element to prevent the influence of fluctuations in the amount of light emitted from the light emitting element.

[Industrial application field]

The present invention relates to a shuttle position sensor that is used in a shuttle type printer and stably detects the position of the shuttle.

A shuttle printer is a type of wire dot printer that has multiple print heads and is designed to print at high speed.The print heads are arranged at equal intervals, and all print heads simultaneously move horizontally and Perform printing. The printing area of one print head is the distance between it and the adjacent print head, and each print head reciprocates over this distance.

The shuttle carries the gutter for printing multiple characters and makes the above reciprocating motion. As a position detection means for this shuttle, a light emitting element, two masks, and a light receiving element are often arranged in this order, and changes in the amount of light from the light receiving element are utilized.

However, since the amount of light from the light emitting element is likely to change due to temperature and other factors, it is necessary to devise measures to accommodate changes in the light emitting output so as not to make mistakes in detecting the position of the shuttle.

[Conventional technology]

FIG. 3 is a perspective view illustrating an example of a shuttle position sensor.

The shuttle 1 prints by moving along a guide rod 6 in the direction of arrow A or B. A mask 4 attached to this shuttle 1
and a mask 3 attached to a fixed stand are located between the light emitting element 2 and the light receiving element 5, and when the holes provided in the masks 3 and 4 overlap, the light from the light emitting element 2 passes through this hole and reaches the light receiving element 5. irradiate.

Masks 3 and 4 have edge detection holes to detect the position where shuttle 1 is reversed on the A side, edge detection holes to detect the position where shuttle 1 is reversed on the B side, and a print that determines the print timing. A hole for clock detection is provided, and the light receiving element 5 is composed of three light receiving elements in order to receive light entering from each hole.

FIG. 4 is a diagram illustrating an example of a mask.

The mask 3 has a hole 10.12 for edge detection and a hole 11 for detecting a print clock, and the mask 4 similarly has a hole 7.8 for edge detection and a hole 9 for detecting a print clock. It is provided.

When the hole 10 of the mask 3 and the hole 7 of the mask 4 overlap, the B side edge of the shuttle 1 is detected by the light from the light emitting element 2 that passes through this hole and reaches the light receiving element 5, and the hole 12 of the mask 3 is detected. When the hole 8 of the mask 4 overlaps with the hole 8 of the mask 4, the A side edge of the shuttle 1 is detected.

The holes 11 of the mask 3 and the holes 9 of the mask 4 are opened at the same pitch, and when these holes overlap, the light receiving element 5 generates a print clock that determines printing timing.

FIG. 5 is a block diagram illustrating an example of a detection circuit.

The circuit that sends the edge detection signal and the print clock detection signal from the output of the light receiving element 5 includes a circuit shown in FIG.
(b) A circuit as shown in (C) is used.

In FIG. 5(a), the output of the light-receiving element 5 is amplified by the operational amplifier circuit 13, compared with the threshold value given by the variable resistor RV by the comparison circuit 14, and an edge or print clock detection signal is detected at a voltage exceeding this threshold value. Send.

In FIG. 5fb), the output of the light receiving element 5 is amplified by an amplifier circuit 15, the DC component is blocked by a capacitor C, and only the AC component is sent to the comparator circuit 16. Comparison circuit 16 compares the alternating current component with a threshold value provided by variable resistor RV, and sends out an edge or print clock detection signal at a voltage exceeding the threshold value.

In FIG. 5(C), the output of the light receiving element 5 is amplified by the amplifier circuit 15 and sent to the peak hold circuit 17 and the comparison circuit 16. The peak hold circuit 17 sends the peak value to the variable resistor RV, and the comparator circuit 16 is given a threshold value from the variable resistor RV, and sends out an edge or print clock detection signal at a voltage exceeding the threshold value.

By the way, when the output of the light receiving element 5 is amplified by the operational amplifier circuit 13 or the amplifier circuit 15 of the detection circuit shown in FIG.
An output like the waveform diagram shown in the figure is obtained. That is, if the vertical axis is voltage and the horizontal axis is time, then FIG. 6(a) is the print crofter waveform obtained from holes 9 and 11 of masks 3 and 4, and FIG. 6(b) is the print crofter waveform obtained from masks 3 and 4. and 4 holes 7 and 10 or 8
This is the edge waveform obtained from and 12.

If the light emitting element 2 (Fig. 3) is a certain distance from the mask 3, the illuminance on the mask 3 will be approximately constant, and as shown in Fig. 6 (a).
The DC component of l(b) is almost the same, and the voltage is 1. FIG. 6 (al) Compare the waveforms of (bl) with the respective thresholds V, , V, and if the waveform is a rectangular wave, the hole area of one of the holes 9 and 11 of masks 3 and 4 is If the hole area of holes 7 and 10 or 8 and 12 is large, the edge waveform will be wider than one of the print clock waveforms and Vt = V3.
When , T-work P<THE.

By the way, in order to increase the S/N ratio, waveform fluctuation 11
It is necessary to increase VHP and VIIE respectively. However, in the print crofter waveform, if you increase the number of masks 3, you can increase the variation amount VHF without changing the wave period, but the edge waveform changes. Unless it is extended to , the width T- will also increase.

Therefore, although we would like to extend the hole vertically, there is a limit to the size of the light-receiving element 5, and it is limited to a size corresponding to this size.In the case of an edge waveform, the width T Wide (wide)

[Problem that the invention seeks to solve]

Incidentally, as described above, the amount of light emitted by the light emitting element 2 fluctuates as the temperature of the surrounding environment fluctuates.

Therefore, even if the variable resistor RV is adjusted and the threshold value ■3 for the edge waveform is optimized to ■3'' so that THE=T, the detection circuit shown in FIGS. Due to component fluctuations or ■□ fluctuations, the rise position of the edge detection signal fluctuates, and the sending timing with the print clock detection signal is shifted, resulting in a change in which print clock is next to the edge. .

As a result, which print clock is next to the edge is not always constant, which causes a problem in that the printing is misaligned.

Further, in FIG. 5(C), the influence of changes in the waveform size due to fluctuations in the amount of light received by the light-receiving element 5 can be prevented to some extent, but since the peak is held, the first waveform is missed. Therefore, if the shuttle reverses itself after seeing the edge detection signal, there is a problem that it cannot be used.

[Means for solving problems]

FIG. 1 is a block diagram of a circuit showing one embodiment of the present invention.

2 is a light emitting element, 4 is a mask attached to the shuttle, 5a is a light receiving element for print clock, 5b is a light receiving element for edge, 18.19 is an amplifier circuit, 20 is a comparison circuit for detecting print clock, 21 is for print clock Amplification circuit 18
22 is a mask attached to a fixed base in which the total area of the print clock holes and the area of the edge holes are approximately the same.

The comparator circuit 21 obtains a threshold value from a print clock waveform created when the light receiving element 5a receives substantially the same amount of light from the light emitting element 2 as the light receiving element 5b through the mask 22, thereby detecting a change in the light receiving element 5b due to a change in the light amount of the light emitting element 2. The edge detection signal is created using a threshold value that compensates for fluctuations in the amount of received light.

[Effect]

With the above configuration, the mask 22 sends out approximately the same amount of light from the light emitting element 2 to the light receiving elements 5a and 5b, and the comparison circuit 21 uses an amplification circuit to determine an appropriate threshold value corresponding to fluctuations in the amount of light emitted from the light emitting element 2. 18, it is possible to send print clock and edge detection signals that are not affected by changes in the amount of light emitted from the light emitting element 2.

〔Example〕

In FIG. 1, the light emitting element 2 uniformly illuminates the mask 22. In FIG. As shown in FIG. 2, the mask 22 is provided with edge detection holes 23 and 24, the areas of which are the same. Further, the print clock detection hole 25 is provided so that its total area is approximately equal to that of the hole 23 or 24.

The print clock waveform detected by the light receiving element 5a is sent to the amplifier circuit 18. The direct current component of the print clock waveform amplified by the amplifier circuit is blocked by the capacitor CI, and only the fluctuation amount VP is sent to the comparator circuit 20. Comparison circuit 20 compares this variation amount VHp with a threshold value and sends a print clock detection signal to terminal E.

Further, the print clock waveform sent out from the amplifier circuit 18 is rectified by a diode RC, divided by resistors R3 and R2, smoothed by a capacitor C2, and then supplied as a threshold value to a comparator circuit 21. Therefore, the light emitting element 2
A threshold value corresponding to fluctuations in the amount of light emitted is supplied.

The edge waveform detected by the light receiving element 5b is sent to the amplifier circuit 19. The edge waveform amplified by the amplifier circuit 19 includes a DC component and is sent to the comparison circuit 21. The comparison circuit 21 obtains a threshold value including the DC component of the print clock waveform from the amplifier circuit 18, and uses this threshold value to calculate the edge waveform variation amount VIIE.
An edge detection signal is detected from and sent to terminal F.

Since the comparator circuit 21 uses the threshold value obtained from the print clock waveform, the edge detection signal is obtained from the edge waveform with an appropriate threshold value that corresponds to fluctuations in the amount of light emitted by the light emitting element 2.
Even if there is a fluctuation in the DC component of the edge waveform or the fluctuation JI V 11 E, the edge and the print clock next to it can always be detected in the same manner.

Incidentally, the relationship between the hole area of the mask and the output of the light receiving element 5 is expressed by the seventh
As shown in the figure, when the voltage is plotted on the vertical axis and the hole area is plotted on the horizontal axis, when the hole area exceeds point D, the output voltage of the light receiving element is not proportional to the hole area and becomes approximately constant.

Therefore, if the total area of the print crofter waveform holes is different from the area of the edge waveform holes 7 and lO or 8 and 12, the 7th
With respect to point D in the figure, the hole area for the print clock, for example, is on the right side, and the hole area for the edge is on the left side, and the output of the light receiving element 5 is balanced between the print clock and the edge. Therefore, there is a problem in that it may be difficult to determine the edge threshold value in relation to the print clock.

However, as mentioned above, since the area of the hole for edge detection and the total area of the hole for print clock detection are the same, the holes of the masks 22 and 4 overlap in the light receiving elements 5a and 5b. When the light emitting element 2 is irradiated with substantially the same amount of light, there is no difference in the output curve shown in FIG. 7 even when the amount of light emitted from the light emitting element 2 changes.

〔Effect of the invention〕

As described above, the present invention can prevent printing misalignment due to fluctuations in the amount of light emitted from the light emitting elements.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a circuit showing an embodiment of the present invention, FIG. 2 is a detailed view of the mask 22 shown in FIG. 1, FIG. 3 is a perspective view illustrating an example of a shuttle position sensor, and FIG. FIG. 5 is a block diagram showing an example of a detection circuit, FIG. 6 is a waveform diagram explaining the output of the amplifier circuit, and FIG. 7 is a diagram showing the relationship between the output of the light receiving element and the hole area. FIG. In the figure, ■ is a shuttle, 2 is a light emitting element, 3, 4, 22 is a mask, 5 is a light receiving element, 6 is a guide rod, 7 to 12 are holes, 13 is an operational amplifier circuit, 1
4.16.20.21 is a comparison circuit, 15, 18.19 is an amplifier circuit, and 17 is a peak hold circuit. Ne, k''month's beautiful gloss example Shioji - 4 Yamaji broff mouth 81 mouth 1 eye mamata 722 details, *f mouth z mouth seal rank 1 begging! q-'Vy・11 Toki Otomei routine play turn 3 eyes mask goo f row detailed 1ro drawing 4 times inspection Bo circuit one flight j friend life mouth/period figure 5 time gift width A hard bathing sword will be held in August! Degree Form Nagiman 6 Diagram Reception: f-tr+l five powers and hole button 1, power attack, and oracle 1
Diagram 7

Claims (2)

[Claims] (1) An edge detection hole that is attached to a shuttle that reciprocates the print head in a direction perpendicular to the paper feed direction, and that detects the end position of the reciprocating range of the shuttle, and a print head that detects the print position of the print head. A first mask (4) having a clock detection hole, overlapping and fixed with the first mask (4), corresponding to the first mask (4),
a second mask (22) provided with an edge detection hole and a print clock detection hole; a light emitting element (2) disposed on one side with the first and second masks in between; and a second mask, and a first light-receiving element (
5a) and a second light receiving element (5b) that receives the light that has passed through the print clock detection hole; and the output of the first light receiving element (5a) is set as a first threshold value. A comparison circuit (21) that compares and sends out an edge detection signal, and a comparison circuit (21) that compares the output of the second light receiving element (5b) with a predetermined second threshold and sends out a print clock detection signal.
0), wherein the first threshold value is a value corresponding to the output of the second light receiving element (5b). (2) The total area of the print clock detection holes provided in the second mask (22) is approximately the same as the area of the edge detection holes. Shuttle position sensor as described.