JPS637961A - Printing position detector in printer - Google Patents

Abstract

PURPOSE:To obtain accurate and stable printing timing, by mounting two pulse generating means generating position detecting pulses and a control means changing over two pulse generators in accordance with the motion position of a head bank. CONSTITUTION:A head bank moving direction detector 304 and a pulse generator 305 constitute a printing start reference position detector D and the second reference voltage V2 of a reference voltage generating circuit 302a is compared with a sensor output signal (a) by a comparator 303a and a reference position starting printing is detected on the basis of a rectangular wave (c) obtained. A digital comparator 307, input data 400 and a gate 310 constitute a gate means F and gate the pulse generated from a printing pulse generator 300A during a time before the count value of a counter 306 (or E) comes to the input data value preset by the input data 400.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a shuttle type serial line printer that uses a magnetic linear scale and a magnetoresistive element as a means for creating print drive timing, and provides accurate and stable print timing. This is what I did to get it.

[Conventional technology]

In a shuttle type serial line printer, as shown in Figure 3, a large number of print elements (dot impact type printing hammers in Figure 3) are played at a constant pitch in directions A and A' that are approximately perpendicular to the paper feed direction B. The head bank 1 is provided with a head bank 1 mounted in the shape of a cylindrical shape, and while the head bank 1 is linearly moved back and forth in directions A and A' by a drive motor (not shown) via an eccentric disk 2, each print element Di is Printing is driven to a plurality of predetermined dot positions.

As shown in FIG. 4, the movement of the head bank 1 is approximately sinusoidal, and is relatively slow near the beginning and end of the printing period (CI, 01'), and is fastest at the middle point.

The instantaneous position of the head bank 1 is detected at regular distance intervals by a position detection device.

Conventionally, a photoelectric rotary encoder has been known as such a position detection device, but recently, a combination of a magnetic linear scale and a magnetoresistive element (MR element) has been used in this type of printer. .

FIG. 5 shows a position detection device consisting of a magnetic IJ near scale and an MR element. The magnetic linear scale 10 has N poles and S poles arranged alternately at a constant pitch H (for example, 423 μm) in directions A and A' that are substantially perpendicular to the paper feeding direction B, that is, in the direction of reciprocating linear movement of the head bank 1. .

The MR element mounting body 20 supports the MR elements F1 to F4, which are arranged in directions A and A' facing the magnetic linear scale 10.

These MR elements Fl-F4 are formed as a vapor deposited film or a sputtered film on a Si substrate or a glass substrate.
They are arranged at intervals of 0.5H and are bridge-connected as shown in FIG. When the MR element mounting body 20 moves in directions A and A' with respect to the magnetic linear scale 1°, a sinusoidal sensor output signal is obtained from the output terminals 21a and 21b of the sensor circuit.

That is, a magnetic field parallel to the film is applied to each MR element Fi, and in response to a change in the direction of this magnetic field, the resistance value of the MR element changes in a sinusoidal manner, and the periodic speed appears to double. .

Therefore, in the sensor circuit of FIG. 8, the MR element Fl.

The resistance value of F3 changes sinusoidally in the same phase, and these and 18
0' phase is different, and the MR element F2. The resistance value of F4 changes sinusoidally in the same phase, and as a result, the output terminals 21a,
From 21b, a multiplied sinusoidal sensor output signal So is taken out as shown in FIG. 9(a).

For example, as shown in FIG. 10, the magnetic linear scale 10 is integrally attached to the lower part of the head bank 1.
The MR element mounting body 20 is fixed to the chassis space 11 so as to face the magnetic linear scale IO in the arrangement shown in FIG.

Therefore, when the head bank 1 moves linearly in the direction A, the magnetic linear scale 10 also moves together, and each MR element of the MR element mounting body 20 moves along the magnetic linear scale 10.
in its longitudinal direction, i.e. A.

A relative linear movement is performed in the N direction, and as described above, a sinusoidal sensor output signal So is obtained from the output terminals 21a and 21b of the sensor circuit as a position detection signal, and this sensor output signal So is waveform-shaped into a rectangular wave. Then, the position detection pulse Pi as shown in FIG. 9 (+) is generated.

The position detection pulse Pi is generated when the MR element Fl-F4 faces the magnetized portion 10a of the magnetic linear scale 10,
This period becomes a printing period 01, 01'.

In addition, as shown in FIGS. 6 and 7, MR elements F+ to F
4 faces the non-magnetized portion 10b, the position detection pulse P
i does not occur, and the period becomes a print stop period or a movement direction switching period Qo, Co'.

When the head bank 1 makes reciprocating linear motion in the directions A and A', the magnetic linear scale 10 and the MR elements F1 to F
The relative positional relationship with 4 changes from the state shown in Fig. 6 (printed material stop period Co), through the state shown in Fig. 5 (printed material stopped period C1), and then to the state shown in Fig. 7 (printed material stopped period Co'). The cycle is then repeated, going through the state shown in FIG. 5 (printing period 01') and returning to the state shown in FIG. 6 (printing stop period Co).

[Problem that the invention seeks to solve]

As described above, since the non-magnetized region is detected in the Co and Co' sections, the output signal So does not generate a substantially sinusoidal wave at the center level of the waveform as shown in FIG. 11(a).

In order to generate the position detection pulse Pi from this output signal So, it is first necessary to convert it into a rectangular wave.

At this time, taking into consideration the noise etc. on the waveform, Figure 11 (
As shown in a), Vs is set to a level slightly higher than the center of the waveform, but this results in a rectangular wave as shown in Figure 11(b), and the resulting Pi as shown in Figure 11(C). This does not result in accurate equally spaced detection.

The present invention was made in view of the above-mentioned problems of the prior art, and provides a shuttle type serial line printer that uses an improved MR sensor output waveform control circuit to obtain accurate and stable print timing. With the goal.

[Means for solving problems]

The configuration of the present invention that achieves the above object detects the head bank position that performs reciprocating linear movement in a predetermined direction, and uses the detected signal to generate a first signal set near the center level of the MR sensor output signal used as a print position timing control signal. and a reference voltage generating means that generates a second reference voltage that is somewhat higher than the first reference voltage, converts the MR output signal into a rectangular wave using the respective reference voltages, and further generates a position detection pulse from this rectangular wave. The present invention is characterized by comprising two pulse generating means for generating , and a control means for switching between the two pulse generators according to the movement positions Co and O+ of the head bank.

[For production]

When the head bank moves linearly back and forth in a predetermined direction, the magnetoresistive element moves linearly back and forth relative to the magnetic linear scale.

When the magnetoresistive element passes through the magnetized portion of the magnetic linear scale, a periodic waveform sensor output signal is generated in response to a periodic magnetic field of north and south poles arranged at a constant pitch.

Furthermore, when the magnetoresistive element passes through a portion of the magnetic linear scale that is not magnetized, that is, a non-magnetized portion, there is no magnetic field large enough to be sensed, so no sensor output signal is generated.

A position detection pulse is generated by subjecting the sensor output signal obtained in this way to signal processing. In the present invention, when the head bank is at the position of the printing body stopping period co and Co', the sensor output signal and the second reference Since the voltage generates a rectangular wave, when a no-signal state is detected and the printing period 01, 01' is generated, an accurate printing pulse can be obtained by creating a rectangular wave using the first reference voltage.

〔Example〕

FIG. 12 shows a magnetic linear scale 100 according to this embodiment. The magnetized unit 100a for obtaining a position detection signal of the magnetic linear scale 100 has an N pole and an S pole, for example, 4
The structure is such that they are alternately arranged at a pitch Pa of 23 μm.

FIG. 13 shows an M-type element mounting body 200 according to this embodiment. This MR element mounting body 200 has a first MR element Fl-
F4 and the second MR, elements 01 to G4 are each 0.
5H pitch, arranged in the x direction, Fig. 14(a)
, a bridge-connected first and second sensor circuit 202 and 204 are formed as shown in FIG.

The magnetic linear scale 100 may be integrally attached to the lower part of the head bank 1 and fixed to the MR element mounting body 200 and the chassis space. Therefore, when the head bank 1 moves linearly in the A and A' directions, the magnetic linear scale 100 also moves together, and each MR element of the MR element mounting body 200 moves in the longitudinal direction of the magnetic linear scale 100, that is, in the A and A' directions. A periodic waveform (more precisely, a sine wave) as shown in FIG. 15 is generated from the output terminals 210, 212 of the first sensor circuit 202 by performing a relative linear movement in the x direction.
A first sensor output signal Sa is obtained.

According to this embodiment, MR output signals Sa and Sb having a phase of 90° are outputted from the MR sensors having a bridge circuit structure 300a and 300b in FIG.
.

The signal is amplified by an amplifier 301b, and waveforms as shown in a and b in FIG. 2 are obtained.

The waveforms of a and b are determined by the second reference voltage v2 303
a.

The comparator 303b provides the rectangular waveforms shown in FIG. 2c and d.

Based on the waveforms c and d, a head puncture movement direction detector 304 obtains a waveform e. This waveform e is inverted when the MR output signal is generated after the pause period (after the head bank movement direction reversal period).

On the other hand, the waveforms a and b in FIG.
As a result, the waveforms shown in FIG. 2 f and g are obtained from the comparators 308a and 308b.

In this case, when the rest period changes to the multi-signal start period, it becomes unstable due to noise and variation in the second reference voltage.

The waveforms f and g are converted into pulses by the printing pulse generators 309a and 309b at the rising and falling edges of rectangular waves, respectively, and when they are added together, the waveform shown in the second figure is obtained.

Here, the most reliable pulse outputs for detecting the reference position for starting printing are c and d waveforms 1 in Figure 2.
The pulse generator 3 is activated at the timing when the C waveform rises to ensure reliable operation.
A pulse is generated from 05, and this pulse causes the counter 30 to
6 is set, and the pulse waveform of h is counted by the counter 306.

Furthermore, if the number of magnetized N and S poles for the magnetic linear scale is N, then the rectangular wave number in the C waveform is N+1. This is because the MR elements Fl-F4 and G1 to G4 are arranged at twice the pitch of the N and S poles of the magnetic linear scale, so that 172 mm is placed at both ends of the magnetized part of the magnetic linear case.
Since the frequency waveforms are added, it becomes +1.

Therefore, 4N numbers of h waveforms are obtained from (N+1) x 2 x 2-4. -4 in this equation is the number indicated by the X mark in FIG.

Therefore, the printing pulse wave number was set to 4N-1 (-1 is the second figure's (
Digital comparator 3
Set the 07 digit and set it to 31 to obtain the above number of pulses.
By switching the gate of 0 using the i waveform, j
Obtain the print pulse waveform. Input data 400 is 4N-1
The value of the input data 400 and the value of the counter 306 are compared in the digital comparator 307, and the gate means 310 is opened with the i waveform until the value of the counter 306 reaches the value of the input data 400, and the h signal is It is allowed to pass.

In the above embodiment, a pair of bridge circuits 300a and 300b are used as means for generating position detection pulses. This is to double the number of pulses of output j and improve accuracy. Therefore, if such accuracy is not required, one of the bridge circuits 300b, the reference voltage generation circuit 302b, and the printing pulse generator 309a
Even if the above is omitted, the gist of the present invention remains unchanged. In this case, since the signal waveform from one of the bridge circuits 300b is used by the head bank movement direction detector 304, means for generating a signal in place of this is provided. As this means, for example, a microswitch or the like for detecting the reversal of the head bank movement direction is provided.

Head bank movement direction detector 304 and pulse generator 30
5 constitutes a print start reference position detector, which compares the second reference voltage V2 of the reference voltage generation circuit 302a and the sensor output signal a by a comparator 303a, and uses the obtained rectangular wave C to start printing. This is to detect the starting reference position.

The digital comparator 307, input data 400, and gate 310 constitute gate means F, and the counter 3
The pulse generated by the print pulse generator 300A (or A) is gated until the count value of 06 (or E) reaches the input data value preset by the input data 400.

[Effects of the Invention] As described above, in the present invention, when converting the MR output signal into a rectangular wave, the first reference voltage and the second reference voltage are used to convert the MR output signal into a rectangular wave. Since the processing configuration employs a signal based on a reference voltage and the signal based on a second reference voltage higher than that as the printing start reference position detection pulse, stable and constant printing timing can be obtained.

[Brief explanation of drawings]

FIG. 1 shows the position detection pulse P by inputting the first and second sensor output signals Sa and sb of the embodiment according to the present invention.
FIG. 2 is a block diagram of a calibration process for generating i, and a timing diagram showing signals of each part to explain the operation of the signal processing circuit. FIG. 3 shows a head bank of a conventional shuttle type serial line link. FIG. 4 is a diagram showing the motion characteristics of the head bank in FIG. 3. FIG. 5, FIG. 6, and FIG. 7 show the relative positional relationship between the magnetic linear scale and the magnetoresistive element (MR element) of other conventional examples. FIG. 8 is a circuit diagram of a sensor circuit consisting of the magnetoresistive element shown in FIG. 5. FIG. 9 is a waveform diagram of a sensor output signal generated by the sensor circuit of FIG. 8. Figure 10 shows the serial line printer shown in Figure 5.
A schematic diagram showing the mounting positional relationship between the magnetic linear scale and the MR element mounting body. FIG. 11 is a waveform diagram of a sensor output signal generated by the sensor circuit of FIG. 5. FIG. 12 is a schematic diagram showing the configuration of the magnetic linear disk scale 10 (of the present invention). FIG.
A schematic diagram showing the arrangement of 4.01-G4. FIG. 14 is a circuit diagram showing the connection configuration of the first and second sensor circuits 202 and 204 in FIG. 12. FIG. 15 shows the first sensor circuit 202 in FIG.
FIG. 3 is a signal waveform diagram of a first sensor output signal Sa obtained from an output terminal of the sensor. FIG. 16 is a signal waveform diagram showing the phase relationship between the first sensor output signal Sa and the second sensor output signal sb. DESCRIPTION OF SYMBOLS 1... Head bank, Dl-Dn... Print element, 10... Magnetic linear scale, 10a... Magnetized part, Fl-F4, Gt-G4... Magnetoresistive element, 20...・MR, element mounting body, 202, 204 ・,
, sensor circuit, 301a, 301b... operational amplifier,
308a, 303a... Comparison amplifier, A, 300
a, 300 b...sensor output signal generation circuit,
B, 302a, 302b ---Reference voltage generation circuit, 0, 309a, 309b ---Printing pattern A
/space generator, D, 304.305...Print start reference position detector, E, 306...Counter, F, 307
,400,310...gate means. OJ$ (n, c ・-
・-Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 9F! A Figure 10 Figure 11 (C) Figure 17-Figure 16 section

Claims (1)

[Claims] While a head bank in which a plurality of print elements are mounted in an array in a predetermined direction substantially perpendicular to the paper feeding direction is linearly moved back and forth in the predetermined direction, each print element is moved to a plurality of predetermined dot positions. A magnetic linear scale having a magnetized portion formed by alternately arranging N poles and S poles at a constant pitch in the predetermined direction and one of the magnetoresistive effect elements facing the scale are integrated with the head bank. a position detection pulse that provides timing for driving the print element to print based on a periodic waveform sensor output signal obtained from the magnetoresistive element when the head bank moves; In a shuttle type serial line printer that obtains
a reference voltage, a second reference voltage that is somewhat higher than the first reference voltage.
a reference voltage generating means for generating a reference voltage; and a printing pulse generator for generating a printing pulse using a rectangular wave signal obtained by comparing one of the reference voltages, a first reference voltage, and the sensor output signal. a print start reference position detector that detects a reference position for starting printing using a rectangular wave obtained by comparing the second reference voltage and the sensor output signal; a counter that is set by a signal from the printer and counts the number of print pulses of the print pulse generator; and a pulse generated by the print pulse generator until the count value of the counter reaches a preset input data value. 1. A printing position detection device for a printer, comprising: gate means for gating.