JPH0472168B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an optical rotary encoder used to control the speed and rotational position of a rotating machine, and in particular to a light-receiving element for compensating for changes in the output of its light-emitting element. The present invention relates to a rotary encoder equipped with a rotary encoder.

[Prior Art] FIGS. 1, 2, and 3 show an example of a general optical rotary encoder of this type. Here, 1 is a rotating slit disk attached to a rotating shaft 2, and the disk 1 has one slit 1A and a large number of slits 1B bored along its periphery as shown in FIG. A slit 1A and a large number of slits 1B are formed on the fixed slit plate 3, which is arranged at a position facing the peripheral part.
Fixing slits 3A, 3B and 3C are formed at positions overlapping with each other (see FIG. 3). As is well known, 1A is for detecting the home position of one rotation, and 1B is for detecting the position of, for example, a printed character.

Reference numeral 4 indicates a light emitting element, and reference numeral 5 indicates a plurality of light receiving elements. As the disk 1 rotates, the light from the light emitting element 4 is transmitted through the fixed slits 1A and 3C at each position where the slit 1A overlaps with the fixed slits 3A, 3B and 3C. 3A, 3B, and 3C and is received by the light receiving element 5, the change in the amount of received light is converted into an electrical signal and output, and control is performed according to the output signal. .

Further, as shown in FIGS. 2 and 3, the light from the light emitting element 4 passes through the slit 1 to the light receiving element 5.
A monitor light receiving element section 5M is provided at a position where light is received without passing through A, 3A, 3B and 3C, and the light emission output from the light emitting element 4 is monitored by this monitor light receiving element section 5M.

That is, since the light emitting element 4 changes its light emitting output due to changes in ambient temperature and changes over time, a monitor light receiving element section 5M is provided to detect the amount of light emitted to compensate for such changes. The light emission output from the light emitting element 4 is controlled by a circuit (not shown) that drives the light emitting element 4 so that the amount of light received by the light receiving element portion 5M is always constant.

However, in such a conventional rotary encoder, the light from the light emitting element 4 is reflected by the rotating disk 1 and is received by the light receiving element 5M after being affected by scattering, confusion, etc. The amount of light received changes regardless of whether the light emission output remains unchanged.

Further, depending on the positional relationship between the rotating machine, the slit disk, and the light receiving element, noise from the rotating machine may have an adverse effect on the light receiving element.

[Objective] The object of the present invention is to eliminate the above-mentioned drawbacks and to provide a monitoring light-receiving element for detecting the amount of light emitted from a light-emitting element.
The monitor light-receiving element is arranged on the same side of the rotating slit disk together with the light-emitting element so that the light received from the light-emitting element is directly detected;
It is an object of the present invention to provide a rotary encoder having a configuration in which the influence of noise of a rotating machine on a light receiving element can be eliminated as much as possible, and furthermore, the rotary encoder can be downsized.

[Example] The present invention will be described in detail below based on the drawings.

4 to 6 show an embodiment of the present invention. In FIG. 4, 6 is a rotating machine, and 7 is an encoder case integrated with the case of the rotating machine 6, which is housed in the encoder case 7. A light emitting element 4 is arranged in the encoder case 7 at a position facing the lower surface of the rotary slit disk 1,
Furthermore, a light receiving element 8 for close position monitoring is provided on the same side so that light received only from the light emitting element 4 is detected.

Now, when the disk 1 directly attached to the rotating shaft 2 of the rotating machine 6 rotates as shown in the figure, the light emitting element 4
The light from the slit 1A of the disk 1 passes through the slits 3A, 3B and 3C of the fixed slit plate 3.
In this example, separate light receiving elements 5A, 5B and 5C are provided at corresponding positions of the fixed slits 3A, 3B and 3C as shown in FIG. Each receives light independently. In addition, these light receiving elements 5
A, 5B and 5C are arranged at positions facing the upper surface of the disk 1 as shown.

Furthermore, at the same time, a part of the light emitting output from the light emitting element 4 is directly received by the monitoring light receiving element 8, and the strength of the light emitting output from the light emitting element 4 is detected, as shown in FIG. 9 is a circuit connected to the light emitting element 4, the light receiving elements 5A, 5B and 5C, and the monitor light receiving element 8 to control the rotating machine 6; 9A has the circuit 9 on its outer surface and a group of light receiving elements on its inner surface; It is a double-sided printed circuit board on which 5 is arranged respectively.

Next, an example of the configuration of the control circuit is shown in FIG. That is, in this example, the light reception signals from the light receiving elements 5A, 5B and 5C are supplied to the negative input terminal sides of the amplifiers 10, 11 and 12, respectively, and the encoder output signals 14, 15 and 15 obtained from the amplifiers 10, 11 and 12 are Rotating machine 6 by 16
control.

Further, the light reception signal from the monitor light receiving element 8 is supplied to the negative input terminal side of the amplifier 13,
The current flowing through the light emitting element 4 is controlled by the monitor output signal from 3, and the amount of light emitted is adjusted.
For this purpose, the configuration is such that the monitor output from the amplifier 13 is supplied to the base of the transistor 17 via the resistor R.

That is, here, since the base potential is kept at a negative potential, when the amount of light received by the monitor light receiving element 8 is large, the potential becomes a negative potential with a large absolute value. Therefore, if the light distribution ability of the light emitting element 4 decreases and its output decreases, the monitor light receiving element 8
Since the amount of light received at the transistor 17 decreases, the base potential rises, the voltage between the base and the emitter of the transistor 17 -V _OP increases, the current supplied to the light emitting element 4 increases, and the amount of light emitted is enhanced.

Furthermore, if the light emitting ability of the light emitting element 4 increases too much, the amount of light received by the monitor light receiving element 8 increases, causing the base potential to drop, and the voltage between the base and the emitter -V _OP to decrease, causing the light emitting element to 4 is controlled.

Note that in the above explanation, the light shielding device provided around the monitor light receiving element 8 was not explained in detail, but as described above, the light received from only the light emitting element 4 is detected by the monitor light receiving element 8. Needless to say, in order to do this, it is necessary to take measures such as installing a hood around the monitor light receiving element 8 as shown in Fig. 4 so that reflected light from the back side of the disk 1 is not received. .

[Effects] As explained above, the rotary encoder of the present invention includes a rotary slit disk that is provided on the shaft of a rotating machine and rotates as the shaft rotates, and a rotary slit disk that faces one surface of the rotary slit disk. a light-emitting element provided between the other surface of the rotating slit disk and the rotating machine; and a light-emitting element provided between the other surface of the rotating slit disk and the rotating machine. , a monitor light-receiving element disposed close to the light-emitting element and receiving light from the light-emitting element; and a monitor light-receiving element accommodating the monitor light-receiving element and the light-emitting element, from the light-emitting element to the monitor light-receiving element; The device is formed by an integrally molded member because it has a light-shielding integrally molded member that forms an optical path to the monitor, and a control means that controls the amount of light emitted from the light emitting element according to the output from the monitor light receiving element. Light from the light emitting element via the optical path can be received by the monitoring light receiving element. This makes it possible to accurately detect changes in the light emission output of the light emitting element and to perform compensation for the light emitting element with high accuracy.
Further, by providing the light emitting element and the monitoring light receiving element in the integrally molded member, it becomes possible to perform the above-mentioned compensation with a simple and compact configuration.

[Brief explanation of drawings]

Fig. 1 is a side view showing an outline of the configuration of a conventional optical rotary encoder as an example, Fig. 2 is a plan view of the slit disk viewed from the bottom side, and Fig. 3 is a side view showing an outline of the configuration of a conventional optical rotary encoder.
The figure is a plan view of the fixed slit plate and the light receiving element viewed from the bottom side, Figure 4 is a partial sectional view showing an example of the configuration of the rotary encoder of the present invention, and Figure 5 is the slit disk viewed from the bottom side. FIG. 6 is a plan view of the fixed slit plate and the light-receiving element viewed from below, and FIG. 7 is a configuration diagram showing an example of the drive circuit of the rotary encoder of the present invention. 1... Rotating slit disk, 1A, 1B...
Slit, 2... Rotating shaft, 3... Fixed slit plate, 3A, 3B, 3C... Slit, 4... Light emitting element, 5, 5A, 5B, 5C... Light receiving element, 5M
... Light receiving element section, 6 ... Rotating machine, 7 ... Encoder case, 8 ... Light receiving element for monitor, 9 ... Circuit, 9A ... Double-sided printed circuit board, 10, 11, 1
2, 13...Amplifier, 17...Transistor.

Claims (1)

[Scope of Claims] 1. A rotating slit disk that is provided on a shaft of a rotating machine and rotates as the shaft rotates; a light-receiving element that is arranged facing one surface of the rotating slit disk; a light emitting element provided between the other surface of the slit disk and the rotating machine; and a light emitting element provided between the other surface of the rotating slit disk and the rotating machine and arranged close to the light emitting element. , a monitor light-receiving element that receives light from the light-emitting element, and a light-shielding unit that accommodates the monitor light-receiving element and the light-emitting element to form an optical path from the light-emitting element to the monitor light-receiving element. A rotary encoder comprising: a molded member; and a control means for controlling the amount of light emitted from the light emitting element according to the output from the monitoring light receiving element.