JPH0510782A - Absolute encoder - Google Patents

Abstract

PURPOSE:To stably hold data about detection so as to detect accurate positions and angles by holding the data of an arithmetic circuit by means of a backup power source when power supplied from a power source is stopped. CONSTITUTION:Slits or magnetic scales which divide the outer peripheral area of a rotating disc 1 at regular intervals into multiple parts are formed and detected by an optical or magnetic head 2. A detection signal of the head 2 is added to a pulse generating circuit 3 and an incremental pulse signals is output and subjected to counting process by an up/down counter 6 and converted into an absolute value. The value is stored in a memory 8 and displayed as an absolute detected value in a display 8. A backup power source 9 provided in parallel with a power source 10 is always charged by the power source 10 using secondary batteries. When power supplied from the power source 10 is interrupted the counter 6 stops but power from the power source 9 is supplied to the memory 7 so that data are safely held and that when the power is resumed detection of positions and angles can be accurately performed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an absolute encoder.

[0002]

2. Description of the Related Art When detecting a linear displacement amount or a rotation angle and performing feedback control in a machine position control or a servo feed motor control, a rotary encoder or a linear encoder is used to detect the displacement amount or the rotation angle. An encoder is used. In that case, the rotary encoder outputs an incremental digital pulse signal according to the rotation angle of the shaft, and the linear encoder outputs an incremental digital pulse signal according to the linear displacement length. Then, an absolute displacement amount or angle can be obtained by counting such an incremental detection pulse signal by a predetermined arithmetic circuit, but the arithmetic circuit is driven by the power supplied from the power source. However, if the supply power suddenly stops for some reason, the detected data will be broken and all the absolute detected values up to that point will be reset to zero.

[0003]

SUMMARY OF THE INVENTION The present invention is an absolute encoder capable of stably holding absolute detection data even in the event of such an unexpected stop of the power supply and accurately detecting the position and angle. It is intended to provide.

[0004]

The above-mentioned object is to provide a backup power supply for backing up the power supply in an absolute encoder provided with an arithmetic circuit for counting output signals of an incremental encoder and performing an absolute output. This can be achieved by an absolute encoder characterized in that the backup power supply holds the data of the arithmetic circuit when the power supplied from the power supply is stopped. or,
When the power supplied from the power source is stopped, it is recommended to provide a brake that stops the encoder in synchronization with this.

[0005]

As described above, according to the present invention, since the backup power source for backing up the power source is provided, even if the power supplied from the power source suddenly stops due to some accident, the arithmetic circuit continues to operate by the backup power source and records it. The created data is retained. Therefore, when the power source is restored again, absolute driving can be continued from that position, and the position, angle, etc. can be accurately detected. In addition, when the power supplied from the power supply is stopped, a brake that fixes the operation of the encoder in synchronization with this is provided to prevent the encoder from moving accidentally while the read head of the encoder or the counter is stopped. Can be prevented, and the reliability of the detected value can be improved.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the embodiments shown in the drawings. In FIG. 1, reference numeral 1 denotes a rotary disk encoder, which forms slits or magnetic scales that divide the outer peripheral area of the disk 1 at equal intervals, and detects this by an optical or magnetic head 2. The detection signal of the head 2 is applied to the pulse generation circuit 3, and the pulse generation circuit 3 outputs an incremental pulse signal according to the rotation direction of the disk. A brake 5 is provided on the rotary shaft 4 of the disk 1, and the pad 5a is pressed against the rotary shaft 4 by a spring 5b to apply a brake. When the coil 5c is excited by a power supply, the brake is released against the spring pressure. It has become.

The incremental pulse signal generated from the pulse generating circuit 3 based on the output of the head 2 of the encoder is applied to the up / down counter 6, where it is counted and converted into an absolute value. The absolute value obtained by counting by the counter 6 is stored in the memory 7 and displayed on the display 8 as an absolute detected value. Reference numeral 9 is a backup power source provided in parallel with the power source 10, which normally uses a secondary battery such as a Ni-Cd battery,
Make sure that the power source 10 is always charging.
Of course, a primary battery such as a Li battery can also be used. This backup power supply is provided for the operation of the memory 7 and holds the stored data so as not to be cleared. An oscillator 11 oscillates a clock pulse to drive the memory 7 and the like. Reference numeral 12 is a power supply circuit for loading the counter 6.

If the power supplied from the power supply 10 is stopped due to some accident, the counter 6 stops, but the memory 7 receives the power supplied from the backup power supply 9 provided in parallel with the power supply 10. The data that has been counted and stored so far is safely retained. The backup power supply 9 is constantly charged to a predetermined voltage by the power supply 10, and the backup is performed at the same time when the power supply 10 is shut down, so that the data is safely held. When the power supply 10 is turned off, the oscillator 11 is also stopped, the memory 7 is not rewritten, and the data is held stably. At this time, the brake 5 provided on the rotary shaft 4 of the disc 1 stops the excitation of the coil 5c at the same time when the power supply from the power source is stopped. It is possible to easily avoid the possibility that an error will occur in the absolute output due to the disk 1 erroneously rotating during the stop of the arithmetic circuit.

When the supply power is restarted, the brake 5 releases the braking action by exciting the coil 5b to enable detection by the encoder, and the counter 6 is loaded by the power supply circuit 12 thereof and the oscillator 11
The writing of the disk of the memory 7 is also performed by the operation of, and the data added to the absolute value held in the memory 7 is sequentially stored and simultaneously displayed on the CRT 8.

FIG. 2 shows a magnetic encoder using a linear magnetic scale 13, 14 is a read magnetic head, and 15 is a pulse generation circuit for outputting an incremental pulse signal corresponding to a detection signal. 16 is a brake that fixes and stops the linear magnetic scale. In this case as well, when the incremental pulse signal output from the pulse generating circuit 15 is processed by the arithmetic circuit based on the detection signal of the magnetic encoder and the absolute output is performed, a backup power supply is provided as in the case of FIG. As a result, even if the power supply is accidentally stopped, the data in the memory can be held safely, and therefore the absolute detection of the position, length, etc. can be performed extremely accurately and highly accurately. As the encoder for detecting the position, length, angle, etc., other than the above-mentioned optical type and magnetic type encoders, those utilizing electrostatic changes and other electrical changes can be arbitrarily used.

[0011]

As described above, the present invention is an absolute encoder provided with an arithmetic circuit that counts encoder signals and outputs an absolute signal, and is provided with a backup power supply for backing up the power supply. Even if the power supply suddenly stops due to some accident, the data of the arithmetic circuit is retained, and when the power is restored again, the absolute drive can be resumed from the retained data, and the position and angle can be detected continuously and accurately. Can be done. Further, when the supply power is stopped, a brake is provided for fixing and stopping the operation of the encoder in synchronization with this, so that it is possible to prevent the encoder from accidentally moving while the arithmetic circuit is stopped. The reliability of the detected value can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of an absolute encoder according to the present invention.

FIG. 2 is an explanatory diagram showing another embodiment.

[Explanation of symbols]

1 rotary disc encoder 2 Detection head 3 pulse generator 4 rotating shaft 5 brake 6 up-down counter 7 memory 8 CRT display 9 Backup power supply 10 power supply 11 clock pulse oscillator 12 power supply circuit 13 Linear magnetic scale 14 magnetic head 15 pulse generator 16 brakes

Claims (2)

[Claims] 1. An absolute encoder provided with an arithmetic circuit (7) for counting output signals of an incremental encoder (1) and outputting an absolute signal,
Backup power supply to back up power supply (10)
(9) is provided, and when the power supply from the power supply (10) is stopped, the backup power supply (9) is used to operate the arithmetic circuit.
An absolute encoder characterized by being configured to hold the data of (7). 2. The encoder (1) is fixed in synchronism with the stop of the power supplied from the power source (10),
Absolute encoder according to claim 1, characterized in that it is provided with a brake (5) for stopping.