JPH05322601A - Phase pulse detector for optical rotary encoder - Google Patents

Abstract

PURPOSE:To provide a phase pulse detector for optical rotary encoder for detecting phase pulses by means of LEDs and phototransistors in which number of components is decreased and phase pulses are detected stably. CONSTITUTION:The phase pulse detector for optical rotary encoder comprises a rotary encoder 14 rotatable together with an object to be detected, a light emitting element 15 disposed oppositely to the rotary encoder 14, a pair of phototransistors 21, 22 juxtaposed closely each other, and a light receiving element 16 disposed oppositely to the light emitting element 15 through the rotary encoder 14. Light emitted from the light emitting element 15 is detected independently by the phototransistors 21, 22, which then produce phase shifted pulse signals respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical rotary encoder phase pulse detector, and more particularly to an optical rotary encoder phase pulse detector using a light emitting diode and a phototransistor.

[0002]

2. Description of the Related Art Generally, in a graphic display device or the like, there is known a coordinate input device used for moving a graphic or a cursor on a screen of a display device (hereinafter referred to as CRT). As a coordinate input device, various structures have been proposed, and as one of them, a coordinate input device so-called "mouse" has been widely used in recent years.

This coordinate input device is roughly rotatably attached to the lower part of a holder, and is brought into contact with the ball body in two directions orthogonal to each other, and rotates independently in correspondence with the rotation direction of the ball body. A pair of rotating members, rotation detecting means for detecting the rotation of the pair of rotating members, and pressing urging means for pressing and urging the ball member toward the pair of rotating members.

Then, the coordinate input device "mouse" is manually moved to rotate the ball body, and the cursor or the like on the CRT screen is moved correspondingly to perform a pointing operation or the like. There is.
(Note that the specific structure of the coordinate input device is described in Japanese Patent Application No. 61-67175 “Coordinate Input Device” previously proposed by the present applicant.
See).

A phase pulse detecting device using an optical rotary encoder is generally used as the rotation detecting means. 7 and 8 show a conventional phase pulse detector 1. In each drawing, 2 is a rotary encoder (having a slit 2a), 3 and 4 are light emitting diodes, and 5 and 6
Indicate phototransistors, respectively. Conventionally, the light emitting diode 3 and the phototransistor 5 are set as one set, and the light emitting diode 4 and the phototransistor 6 are set as one set, and each set is arranged at an angle θ as shown in FIG. The phase pulse detection device 1 is shown in FIG.
Shows the state of being incorporated into. As shown in the figure, the coordinate input device 7 incorporates two sets of phase pulse detection devices 1 corresponding to the X coordinate and the Y coordinate. Further, in the figure, 8 indicates a ball body, and 9 and 10 indicate rotating members.

[0006]

However, the above-mentioned conventional phase pulse detection device 1 has a problem that a large number of parts are required because two light emitting diodes 3 and 4 and phototransistors 5 and 6 are required. It was

Further, since the sets of the light emitting diodes 3 and 4 and the phototransistors 5 and 6 are arranged so as to be separated by an angle θ, the structure in the vicinity of the rotary encoder 2 becomes complicated and the assembling work is also troublesome. There were challenges. Further, the phototransistors 5 and 6 are mounted and positioned on the holder 11. At this time, the phototransistors 5 and 6 need to be positioned and mounted with high precision at the above-described predetermined angle θ. Is difficult,
In addition, there is a problem in that the phase difference between the output waveforms becomes unstable because variations easily occur.

The present invention was created in view of the above points, and an object of the present invention is to provide a phase pulse detecting device for an optical rotary encoder capable of reducing the number of parts and performing stable phase pulse detection. To do.

[0009]

In order to solve the above problems, according to the present invention, a phase pulse detecting device for an optical rotary encoder is provided in a rotary encoder that rotates with the rotation of a detected object, and in this rotary encoder. One light-emitting element arranged to face each other and a pair of phototransistors arranged in close proximity to each other, and a light-receiving element arranged to face the one light-emitting element via a rotary encoder. Composed by and.

Then, each phototransistor independently detects the light from the one light emitting element to generate a phase pulse signal.

[0011]

By constructing the phase pulse detector for the optical rotary encoder as described above, it is possible to generate the phase pulse signal by operating the two phototransistors with the light from one light emitting element. The number of light emitting elements can be reduced by one. Further, the light receiving element has a structure in which a pair of phototransistors are arranged close to each other, and can be handled as one component, and the assembling work can be easily performed. Further, since the pair of phototransistors are integrally incorporated to form a light receiving element,
The pitch (distance) between the phototransistors is always constant, and the phase difference of the output waveform can be stabilized.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 and FIG. 2 are main part configuration diagrams of a phase pulse detection device 12 for an optical rotary encoder (hereinafter, simply referred to as a detection device) which is an embodiment of the present invention. 3 is a diagram showing a state in which the detection device 12 is incorporated in the coordinate input device 13.

As shown in each figure, the detection device 12 is
Rotary encoder 14, light emitting element 15 and light receiving element 1
It is composed of 6 and the like.

As shown in FIG. 3, the rotary encoder 14 is attached to a shaft 18 which rotates in accordance with the rotation of a ball 17 which is an object to be detected, and rotates integrally with the shaft 18. The rotary encoder 14 has slits 14a formed at a predetermined pitch.

The light emitting element 15 is, for example, a light emitting diode having a well-known structure, and is arranged at a position facing the slit 14a of the rotary encoder 14. Only one light emitting element 15 is provided in the detection device 12, as described later.

The light-receiving element 16 is a feature of the present invention, and has a structure in which two phototransistors 21 and 22 are arranged side by side in a resin body 19 at a predetermined pitch P as shown in FIG. .. The phototransistors 21 and 22 are formed on the same wafer by using the thin film technique, and there is no difficulty in forming them in proximity, and the pitch P between the phototransistors 21 and 22 is also determined with high accuracy. be able to. As shown in FIG. 5, the circuit configuration is such that the emitters are common, and therefore the three terminals 2
3a to 23c extend, and each of the terminals 23a to 23c
c is connected to the circuit board 24.

The light receiving element 16 having the above structure is arranged at a position facing the light emitting element 15 through the rotary encoder 14. At this time, the light emitted from the light emitting element 15 is the light receiving element 1
The six phototransistors 21 and 22 are irradiated together. As a result, one light emitting element serves as a light source common to the two phototransistors 21 and 22.
Therefore, in the conventional case, the number of light emitting elements required to be two, which corresponds to the number of phototransistors, can be reduced to one, and the number of components can be reduced.

As described above, the two phototransistors 2
Even if the light emitting element 15 is commonly used for 1 and 22,
A phase pulse signal capable of detecting the rotating state of the rotary encoder 14 is reliably generated from each of the phototransistors 21 and 22. That is, in FIG. 2, the rotary encoder 1
Considering the case where 4 rotates in the direction of the arrow in the figure, the movement of the slit 14a associated with this rotation causes the phototransistor 21 to face the light emitting element 15 and be irradiated with light, and then the phototransistor 22. Is irradiated. Slit 14
The pitch a and the pitch P of each phototransistor 21, 22 are appropriately selected.
It is configured so that the light is not simultaneously applied to the 1, 2 and 22 and the light is not blocked. Therefore, the phase pulse signals output from the phototransistors 21 and 22 have a phase difference corresponding to the pitch P.

FIG. 6 shows the waveform of the phase pulse signal generated by each of the phototransistors 21 and 22 (note that the waveform before analog-digital conversion is shown in FIG. 6). In the figure, (a) is a signal waveform output from the terminal 23b of the phototransistor 21, and (b) is a terminal 23c of the phototransistor 22.
The signal waveform output from is shown. As shown in the figure, each waveform has a phase difference caused by a difference in the arrangement position (pitch P) of the phototransistors 21 and 22.
The rotation direction of the rotary encoder 14 can be detected from this phase difference, and the rotation speed of the rotary encoder 14 (that is, the detected object) can be detected from the frequency of each waveform. As described above, since the phototransistors 21 and 22 are integrally formed and the pitch P between them is determined with high accuracy, the phase difference generated between the generated phase pulse signals may vary. This is not the case, and the signal detection accuracy can be improved.

Here, comparing the coordinate input device 13 (shown in FIG. 3) to which the detection device 12 according to the present invention is applied with the conventional coordinate input device 7 (shown in FIG. 9), the detection device 12
Since the light emitting element 15 and the light receiving element 16 may be arranged to face each other at one position of the rotary encoder 14, the structure inside the coordinate input device 13 is very simple. Therefore, the assembling work of the coordinate input device 13 can be easily performed. Further, the phototransistors 21 and 22 are the light receiving elements 16
Since it is integrally incorporated in the resin body 19 and can be handled as one part, the structure can be simplified and the assembling workability can be improved.

Further, as described above, in the detection device 12, 1
Two phototransistors 21, 22 with one light emitting element 15
Since they can be operated together, it is possible to reduce the number of light emitting elements by one as compared with the conventional one. Especially when this is used for the coordinate input device 13, the detection device 1 for the X and Y coordinates respectively.
Since 2 is provided, two light emitting elements can be reduced,
Thereby, the power consumption of the coordinate input device 13 can be reduced. By reducing the power consumption of the coordinate input device 13 in this manner, the battery life of the personal computer can be extended, especially when the device 13 is connected to a battery-powered personal computer or the like, which is a great advantage.

[0022]

As described above, according to the detecting device of the present invention, the number of parts can be reduced and the assembling can be simplified, and the power consumption can be reduced by reducing the number of light emitting elements. By using photo detectors in which multiple phototransistors are juxtaposed in parallel, the variation that occurs in the conventional assembly can be reduced and the phase difference of the output waveform can be stabilized and the detection accuracy can be improved. In addition, it has features such as low power consumption.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a detection device according to an embodiment of the present invention.

FIG. 2 is a view on arrow AA in FIG.

FIG. 3 is a diagram showing a case where the detection device according to the present invention is applied to a coordinate input device.

FIG. 4 is a diagram for explaining a light receiving element.

FIG. 5 is a circuit diagram of a light receiving element.

FIG. 6 is a diagram showing an output waveform of a light receiving element when the detection device operates.

FIG. 7 is a main part configuration diagram of an example of a conventional detection device.

FIG. 8 is a main part configuration diagram of an example of a conventional detection device.

FIG. 9 is a diagram showing a coordinate input device provided with a conventional detection device.

[Explanation of symbols]

 12 detection device 13 coordinate input device 14 rotary encoder 15 light emitting element 16 light receiving element 21, 22 phototransistor

Claims (1)

[Claims] 1. A rotary encoder that rotates in accordance with the rotation of an object to be detected, one light-emitting element that is arranged so as to face the rotary encoder, and a pair of phototransistors are arranged in close proximity to each other. The phototransistor has a structure and is configured by the one light emitting element and a light receiving element disposed opposite to the one light emitting element via the rotary encoder, and each phototransistor independently outputs light from the one light emitting element. A phase pulse detector for an optical rotary encoder, which is configured to detect and generate phase pulse signals respectively.