JPH0457039A - Pulse encoder signal processing circuit - Google Patents

Abstract

PURPOSE:To execute the signal processing corresponding to a difference of characteristics of the respective photointerrupters by connecting selectively plural photointerrupters to one waveform shaping circuit, and also, switching the signal input gain of the waveform shaping circuit. CONSTITUTION:A CPU (2), first of all, selects a motor to be driven by motor selecting signals (MSL0, MSL1), and subsequently, executes the driving control by motor control signals (MCW, MCCW). That is, by a state of the motor selecting signals (MSL0, MSL1), a multiplexer (13) switches the motor control signals (MCW, MCCW) to one of motor driving amplifiers (14a, 14b, 14c), a pulse encoder selecting circuit (12) sets a photointerrupter (one of 31a, 31b and 31c) corresponding to a motor to be driven (one of 32a, 32b and 32c) to an active state, and also, a waveform shaping circuit (11) sets an input gain corresponding to the photointerrupter set to the active state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a signal processing circuit for a pulse encoder that monitors the amount of displacement of an actuator or a mechanical member driven by the actuator.

[Prior Art 1] Conventionally, various displacement sensors have been used for mechanical control, particularly position control, in the field of mechatronics, including cameras. Among them, photo ink converters (hereinafter referred to as "photo ink converters") are used for many reasons such as high resolution, high reliability, low cost, and small size.

Photo ink lathers and photo reflectors are collectively called photo ink lathers and are most commonly used.

Now, different models of this photo ink clubter have very large differences in electrical characteristics due to differences in semiconductor element characteristics and physical dimensions such as size, shape, and slit width since they are optical sensors. arise. Therefore, when using a plurality of photointerrupters, separate waveform shaping circuits with different input gains and the like are provided for each photointerrupter.

[Problems to be Solved by the Invention] However, if a separate waveform shaping circuit is provided for each photoinclutter, the circuit scale becomes large (in addition, the number of signal lines increases, making the wiring complicated, etc.) This could negate many of the advantages of photo ink printers.

[Objective of the Invention] Therefore, the object of the present invention is to solve the drawbacks of the conventional photointerrupter and to create a pulse generator that uses a plurality of photointerrupters but has a simple configuration and does not increase the circuit size. An object of the present invention is to provide an encoder signal processing circuit.

[Means for solving the problem] In mechatronic devices such as cameras that are powered by batteries, it is rare to drive multiple actuators at the same time due to battery performance issues, and therefore the waveform shaping circuits also operate at the same time. Very rarely.

Focusing on this point, the present invention selectively connects a plurality of photointerrupters to one waveform shaping circuit, and further switches the signal input gain of the waveform shaping circuit according to the selected photointerrupter. Accordingly, signal processing corresponding to the difference in characteristics of each photointerrupter is performed.

[Embodiment] FIG. 1 is a block diagram of a control system including a pulse encoder signal processing circuit according to an embodiment of the present invention.

The interface section (1) consists of a pulse encoder signal processing circuit and a motor driver circuit, and literally connects the CPU (2) and the mechanical section (3A, 3B).
, 3G).

Furthermore, the pulse encoder signal processing circuit is connected to the waveform shaping circuit (11) and the pulse encoder selection circuit (12), and the motor driver circuit is connected to the multiplexer (12).
3) and motor drive amplifier (14a, 14b, 14.0
).

The first mechanical section (3A) includes the motor drive amplifier (1
4a), and a first photointerrupter (32a) that monitors the amount of displacement of the first motor (32a).
31a). The second and third mechanical parts are similarly configured.

Three photo interrupters (31a, 31b, 31c
), the collector of the phototransistor and the anode of the LED are wired in common, the former being connected to the input of the waveform shaping circuit (11), and the latter being connected to the current limiting resistor (R31).
connected to the power supply via. In addition, the emitter of each phototransistor and the cathode of the LED are connected,
It is connected to the output of the pulse encoder selection circuit (12).

Between the interface section (1) and the CPU (2),
Motor selection signal (MSLO, MSL 1).

Motor control signals (MCW, MCCW) and a pulse signal (PLS) that is the output of the waveform shaping circuit (11)
are connected by.

Now, in the above configuration, the CPU (2) first selects the motor to be driven using the motor selection signals (MSLO, MSL 1 ), and then selects the motor to be driven using the motor control signals (MCW, MC
CW) to perform drive control. That is, depending on the state of the motor selection signal (MSLO, MSL 1), the multiplexer (13) outputs the motor control signal -Pf (MCW, MCC
W) to the motor drive amplifier (14a, 14b, 14C)
The pulse encoder selection circuit (12) activates the photointerrupter corresponding to the motor to be driven, and the waveform shaping circuit (11) activates the activated photointerrupter. Set the input gain accordingly. The truth table for this function is shown in Table 1.

FIG. 2 shows the detailed configuration of the waveform shaping circuit (11).

Transistors Ql, Q2, G3, G4 with equal characteristics
constitutes a current mirror circuit, and the bias current source (C9
1, C32), analog switch (ASWl, AS
W2.1sW3) and the analog switch switching gate (G1.G2) constitute an input gain switching section. and.

This input gain switching is performed using the motor selection signal (M
This is done automatically depending on the state of SLOIM, S L 1 ). In other words, the motor selection signal (MSLOlMSL
1) The input gain is set according to the output level of the photointerrupter corresponding to the selected motor. Incidentally, this input gain is normally set so that the voltage converted by the current-voltage converter, which will be described later, has a margin with respect to the power supply voltage of the circuit and is maximized.

Now, for example, if the first motor selection signal (MSLO) is
When the second motor selection signal (MSLl) is at the "H" level, the individual analog switches are ASW1=OFF, ASW2=ON, ASW3=OFF as shown in Table 2.
Therefore, the input gain is Ql:(Q3+Q4) = 1:2, which is twice the input gain. Therefore, the twice amplified current flows through the diode (DI
, D2), flows into a current-voltage converter formed by a resistor (R1), and is converted into a logic-level pulse signal (PLS) by a subsequent waveform shaping unit. Note that this waveform shaping section is a well-known AC detection type waveform shaping circuit, and detailed explanation thereof will be omitted.

Also, when the motor selection signal is a combination other than the above, each analog switch is set to ASW1=O as shown in Table 2.
N, ASW2=OFF, ASW3ON, and the input gain is Ql:G2=1:1, which is 1x.

Table 1 [Effects of the Invention] As described above, according to the present invention, it is possible to provide a pulse encoder signal processing circuit that uses a plurality of photointerrupters, has a simple Qi configuration, and does not increase the circuit scale. . Therefore, it is possible to construct a low-cost, high-resolution system while fully utilizing the advantages of the photoink clubter.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a control system including a pulse encoder signal processing circuit which is an embodiment of the present invention, and Fig. 2 is a block diagram of a control system including a pulse encoder signal processing circuit which is an embodiment of the present invention. ...Interface part 2...
......CPU 3A, 3B, 3C ......Mechanical section 11...Waveform shaping circuit 12...Pulse encoder selection circuit 13
......Multiplexer 14, a, 14b,
14. c...Motor drive amplifier 31a, 31b
, 31c...Photo ink converter 32a, 32
b ,, 32 c ...Motor patent applicant Minolta Camera Co., Ltd.

Claims (4)

[Claims] (1) A plurality of actuators, a plurality of pulse encoders that generate a pulse train according to the amount of displacement of a mechanical member driven by these actuators, and a plurality of pulse encoders that convert the pulse train from the pulse encoder into a logic signal. A pulse encoder signal processing circuit comprising a waveform shaping circuit and a pulse encoder selection circuit selectively connecting one of the plurality of pulse encoders to the waveform shaping circuit. (2) The pulse encoder signal processing circuit according to claim 1, wherein the pulse encoder is a photo interrupter or a photo reflector. (3) The pulse encoder signal processing circuit according to claim 1, wherein the pulse encoder selection circuit selects the pulse encoder based on a selection signal from the actuator. (4) The pulse encoder signal processing circuit according to claim 1, wherein the waveform shaping circuit is capable of switching the signal input gain from the pulse encoder by a selection signal from the actuator.