JPH04324315A - Encoder - Google Patents

Abstract

PURPOSE:To enable a relative position information to be detected by using an encoder in simple structure and then an absolute position information to be calculated and output based on it without requiring a power supply for a back-up memory. CONSTITUTION:In an encoder 11 which detects a relative position information, an encoder output of a magnetic recording medium 12 is stored in an EEPROM 28 and a CPU 25 calculates and outputs an absolute position information of the magnetic recording medium 12 from a memory value of this EEPROM 28 and the encoder output (relative position information). Since the EEPROM 28 which is a no-volatile semiconductor memory retains an accumulation value of the relative position information even if a power supply 17 is OFF, the absolute position information can be obtained easily based on this accumulation value.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an encoder, and is configured to detect an absolute position using a relative position detection type encoder by storing the output of the relative position detection type encoder in an EEPROM at any time. .

0002

[Prior Art] Conventionally, encoders used in machine tools, robots, etc. have been of the relative position detection type.
There is also an absolute position detection type.

For example, an absolute type (absolute position detection type) optical rotary encoder uses a main scale in which slit rows with different pitches are arranged in multiple stages. A light receiving element is attached to each slit row, and the outputs of these light receiving elements are processed by, for example, a CPU to detect the absolute position.

However, in such an absolute type rotary encoder, in order to memorize the number of rotations during multiple rotations, a large capacity semiconductor memory must be installed together with a backup power supply, and its maintenance is troublesome. However, the disadvantage was that the configuration of the equipment was complicated.

[0005] Therefore, it has been considered to detect the absolute position using a relative position detection type rotary encoder which does not have such drawbacks. The magnetic rotary encoder in this case has a magnetic recording medium magnetized with multiple poles at regular intervals on its outer periphery, and a magnetic sensor is disposed close to the outer periphery. This magnetic sensor uses a magnetoresistive element to detect changes in magnetic poles and outputs a signal indicating relative position.

[0006] When converting the incremental output (relative position information) of the rotary encoder into an absolute, the detected current position information has been recorded in a DRAM. This data was used to perform arithmetic processing to obtain absolute position information.

[0007]

However, such a conventional magnetic rotary encoder requires a backup power source to retain data in a DRAM, which is a volatile semiconductor memory. This is because the contents will be lost in a few weeks unless the power source is replenished by charging or the like.

Therefore, the present invention provides an encoder that does not require a memory backup power supply, has a simple configuration, is easy to maintain, and can detect the position of the machine without operating it when the power is turned on. Its purpose is to provide.

[0009]

[Means for Solving the Problems] The present invention provides a recording medium on which relative position information is recorded, a detection means for detecting the relative position information from the recording medium, and a system for accumulating the detected relative position information and calculating the absolute position information. calculation means for calculating information, and the calculation means is an encoder having a nonvolatile memory that stores the cumulative value of the relative position information. In this case, the present invention can be applied to both magnetic encoders and optical encoders. Furthermore, the present invention can be similarly applied to both rotary encoders and linear encoders.

0010

[Operation] The encoder according to the present invention detects relative position information by the detection means and stores this relative position information in a nonvolatile memory as a cumulative value. Then, the calculation means calculates absolute position information based on the relative position information, which is the cumulative value stored in the nonvolatile memory.

[0011]

Embodiments Hereinafter, embodiments of the encoder according to the present invention will be described with reference to the drawings. 1 to 3 are diagrams for explaining one embodiment of the present invention. In this embodiment, the present invention is applied to a magnetic rotary encoder.

As shown in FIG. 1, this magnetic rotary encoder 11 has a disc-shaped magnetic recording medium 12 and a magnetic sensor 13. The magnetic recording medium 12 has position information recorded on its outer peripheral surface. For example, this outer peripheral surface is magnetized with a predetermined magnetic force (for example, 200 to 300 Oe) at regular intervals along the circumferential direction, and N poles and S poles are alternately formed. These magnetic poles constitute position information.

On the other hand, the magnetic sensor 13 has a magnetic resistance element disposed close to and opposite to the outer peripheral surface of the magnetic sensor 13, and an analog output voltage of the magnetic resistance element is inputted to a comparator 16 via an amplifier 15. ing. Comparator 16
compares the output voltage of the relative position information input via the amplifier 15 with the reference voltage Vref, converts it into a binary value, and outputs it as an encoder output (incremental data). In this encoder 11, the power supply 17 connects the amplifier 1.
5. Power is supplied to the comparator 16.

Reference numeral 21 denotes a control section which processes the encoder output and outputs it as an absolute data output. This control section 21 includes a counter 22 that counts the encoder output, a backup power supply 23 for this counter 22, a data input/output section (I/O) 24, and a CPU.
25, ROM26, RAM27, EEPROM2
8. In addition, the counter 22, the input/output section 2
4, CPU25, ROM26, RAM27, EEPRO
M28 is connected by a common bus 29. Further, the backup power supply 23 can also be used for backup of the encoder 11.

The EEPROM 28 stores the encoder output (relative position information). Furthermore, by using the EEPROM 28 as a nonvolatile memory, data can be rewritten while it is mounted on a circuit. In addition, the CPU 25 has this EEPROM 28
Absolute position information (absolute data) is calculated from relative position information by performing arithmetic processing based on the data stored in , and the value of the counter 22.

The arithmetic processing executed by the CPU 25 will be explained below with reference to the flowcharts shown in FIGS. 2 and 3. First, when power is being supplied to the encoder 11 from the power source 17, an encoder output generated by the rotation of the magnetic recording medium 12 is detected (S21), and this encoder output is input. When this encoder output is input,
For example, the CPU 25 stores EEP in the working RAM 27.
The stored value stored in the ROM 28 is read out (S22). Then, based on the encoder output detected in step S1 this time and the stored value of this EEPROM 28, for example, addition or subtraction is performed (addition if rotating in one direction, subtraction in the opposite direction) to obtain an absolute value for the magnetic recording medium 12. Data is calculated (S23). The calculated absolute data is stored in the EEPROM 28 (S24), and is outputted to the outside from the input/output section 24 (S25). This process is repeatedly executed in synchronization with the cycle of detecting the encoder output. Therefore, the encoder output from power on to power off is EEPROM28.
This is what is accumulated and stored.

Further, when the power supply 17 of the encoder 11 is cut off, it is assumed that only the amplifier 15, the comparator 16, and the counter 22 of the encoder 11 are energized from the backup power supply 23. therefore,
When the magnetic recording medium 12 moves during this power-off, the amount of movement is accumulated in the counter 22 as an encoder output from the comparator 16. Also, during this period, E
The EPROM 28 only stores the cumulative encoder output from power ON to power shutdown, and the CPU 25
Therefore, it is not added.

Further, when the power supply 17 of the encoder 11 is turned on again after being cut off, the following initialization process is executed. That is, first, the stored value (relative position information) of the counter 22 based on the output of the encoder 11 is read out (S31), and the stored value of the EEPROM 28 is read out (S32). It is determined whether these stored values match each other (S33), and if they match, the stored values are output as they are as absolute position information (absolute data). In this case, the magnetic recording medium 12 was not rotating when the power was cut off. On the other hand, if these values do not match, the value stored in the EEPROM 28 is corrected based on the value stored in the counter 22 (S34). It is assumed that the value stored in the counter 22 is added to or subtracted from the value stored in the EEPROM 28. This is to correct the amount of movement of the magnetic recording medium 12 when the power supply is interrupted, using the stored value (relative position information) of the counter 22 accumulated and stored during that period. and,
This correction value is written and stored in the EEPROM 28 (S35). This updated correction value is output as absolute data.

[0019]

[Effects of the Invention] According to the present invention, since relative position information is recorded using a non-volatile memory such as EEPROM instead of DRAM, a backup power source for the memory is not required, and relative position information is permanently retained. can do. Furthermore, the absolute position of a machine, etc. can be detected when the power is turned on using an encoder with a simple configuration. Furthermore, the encoder is easy to maintain.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a magnetic rotary encoder according to an embodiment of the present invention.

FIG. 2 is a flowchart of a magnetic rotary encoder according to an embodiment of the present invention.

FIG. 3 is a flowchart of a magnetic rotary encoder according to an embodiment of the present invention.

[Explanation of symbols]

11 magnetic rotary encoder, 12 magnetic recording medium, 13 magnetic sensor (detection means),
25 CPU (calculation means), 28 EEPRO
M (non-volatile memory)

Claims (1)

[Claims] [Claim 1] A recording medium on which relative position information is recorded;
The calculation means includes a detection means for detecting relative position information from the recording medium, and a calculation means for accumulating the detected relative position information to calculate absolute position information, and the calculation means calculates the cumulative value of the relative position information. An encoder characterized by having a nonvolatile memory for storing.