JP2003035564A - Absolute position detecting encoder and method for detecting original position - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems that in conventional technologies, because of the need for accurately detecting the width of each original position signal, the width varies when the temperature or a power source varies, and so the absolute original position is detected wrongly, and a lot of original position signals and original position signals with wide width are required, and therefore, it is difficult to detect the original position signal accurately. SOLUTION: The absolute position detecting encoder, which detects the absolute position from incremental signals and the original position signal used as a reference signal, has at least two groups of original positions composed so that at least three original position signals are output. A group of the original position signals from the group of original positions has a function for detecting the absolute position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple absolute value encoder capable of detecting an absolute value with a short distance movement in an encoder which outputs an incremental signal, and a method for detecting the origin thereof.

[0002]

2. Description of the Related Art As conventional encoders for position detection, there are an absolute encoder and an incremental encoder that counts the number of pulses of an output signal. As shown in FIG. 4, the incremental encoder passed through a scale 1 having a main slit and an origin slit, a light emitting element 2, a fixed side slit 3 for detecting A, B, and Z channels, and a fixed side slit 3. It is composed of a light receiving element 4 for converting a change in light quantity into an electric signal, and a waveform shaping circuit 5 for converting a detection signal into a rectangular wave.
The A and B channel output signals have an electrical phase difference of 90 degrees, and can detect the moving direction and the moving amount. In addition, the origin slit 6 that detects the origin
Is arranged at one place on a scale different from that of the main slit 7, and this position is output as a Z-channel output signal as an origin signal, so that the position moved based on this place can be detected. Although the incremental encoder has a simple detection configuration and is low cost, the absolute position cannot be detected when the power is turned on, and when it is attached to a mechanical device, etc., the machine is moved once to the home to detect the home signal when the power is turned on. It was indispensable to return to the origin, which means that it had to move to the specified position again. Therefore, there is a demand for an absolute value encoder that does not require a home position return operation, but the absolute value encoder has a problem that the structure for detecting an absolute position is complicated and the cost is high.

Therefore, a simple absolute value encoder, which is an incremental encoder but can detect an absolute position with a short distance of movement, is conceivable. As shown in Japanese Patent No. 2634627, the width of a plurality of origins is changed to change the width. A simple absolute value encoder that detects an absolute position by detecting the absolute position is disclosed. The disclosed simple absolute encoder has a large number of origin slits that can detect absolute positions in advance.When the power is turned on, the absolute position can be detected by passing through any of the arranged origin slits. A home position return operation is necessary, but it has the feature that it is cheaper than the absolute encoder.

[0004]

However, in the prior art (Japanese Patent No. 2634627), since it is necessary to accurately detect the width of each origin signal, the width changes when a temperature change or power supply fluctuation occurs, and the absolute origin There is a problem that it is detected by mistake. In addition, in the case of detecting a long-distance absolute position, many origin signals are required, a wide origin signal is required, and it becomes difficult to detect an accurate origin signal. Further, since the origin for detecting the absolute position serves as a reference for all positioning, it is necessary to surely detect the origin, and a highly reliable origin has been required. Therefore, it is an object of the present invention to provide a simple absolute value encoder and an origin detection method which are more reliable in the origin detection method of the encoder than the conventional simple absolute value encoder and are resistant to external noise and the like and which have high reliability. It is what

[0005]

In order to solve the above-mentioned problems, the invention of claim 1 is an absolute position detection encoder for detecting an absolute position from an incremental signal and an origin signal which is a reference signal. An absolute position detection encoder comprising at least two origin groups configured to output three, and an origin signal group from the origin group having an absolute position detection function. The invention of claim 2 is the absolute position detection encoder of claim 1, wherein the intervals of the origin signal positions of the origin signal group are the same, and the invention of claim 3 is that the origin signal group is The absolute position detection encoder according to claim 1 or 2, wherein the encoders are arranged at equal intervals, and the invention according to claim 4 is such that the distance between the origin groups is the original position within each origin signal group. Claims 1, characterized in that greater than the spacing of the signal position is an absolute position detection encoder according to any one of 3. Further, the invention of claim 5 is characterized in that the origin signal is output from a detection section constituted by a slit, a magnetic pole or an electrode in which two or more are combined. The absolute position detecting encoder according to claim 6, wherein the absolute position detecting encoder detects the origin signal by counting the intervals of the origin signal positions in each origin signal group. This is the origin detection method of the detection encoder.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The simple absolute value encoder of the present embodiment is composed of a scale having the contents shown in FIG. The simple absolute value encoder of the present invention, in the scale 1 of FIG.
Only the origin slit configuration is different, so the configuration of the slit portion is shown. The origin detection method for detecting the absolute position is detected by the control circuit that receives the incremental encoder signal shown in FIG.

The scale is composed of a main slit 7 and origin group slits Z1 to Z4. Origin group slit Z1
Consists of three origin slits Z11, Z12, and Z13. In addition, other origin group slit Z
2 to Z4 are also composed of the same three origin slits. However, the intervals of the origin slits are different from each other, and the pitch P of the main slit 7 is Z11-Z.
12P is 1P, Z12-Z13 is 4P, and Z2
1-Z22 is arranged as 2P, and Z22-Z23 is arranged as 3P. Further, the distance between the origin group slits Z1 and Z2 is arranged to be larger than the distance between the origin slits, and in this embodiment, it is 5P. That is, the distance between the origin slits in the origin group slit is detected, and 1P-4P is the origin group slit Z1, 2P-.
The 3P is a method of detecting the origin group slit like the tenth digit and the one digit of the number, like the origin group slit Z2. In addition, when detecting the absolute position of a long distance,
It goes without saying that it is better to widen the intervals between Z11 and Z12 and between Z12 and Z13. Further, if the number of origin slits in each origin group is set to four, the configuration will be the same as the addition of hundreds of digits, so there is no problem even when detecting an absolute position at a longer distance.

Next, a method of detecting an absolute position using this simple absolute value encoder will be described. First, FIG.
The receiving side control circuit has a main slit pitch (1P)
And the number of origin slit groups (4) and the distance between origin slits at one end of the scale 1 (interval between Z11 and Z12: 1P, Z12
And Z13: 4P), the distance between the origin slits at the other end of the scale 1 (Z41 and Z42: 4P, Z42 and Z43)
Interval: 1 P), the change amount of the origin slit group (the value of the change amount of the minimum pitch) (in the embodiment, since it increases in 1P units, 1 P), the distance between the origin slit groups (in the embodiment, 5P) or the like is stored in advance in the memory (21) in the control circuit as the initial value of the simple absolute value encoder.

In this state, when the power is turned on with the fixed side stopped at the position of point C in FIG. 1, the detector including the light emitting / receiving element is moved to the right after the power is turned on ( Note that the scale may be moved to the left, but this is done for convenience of explanation). The amount of movement until the origin signal Z31 is detected is counted as an A channel signal by the counter (22) in the control circuit (2P pulse in this case), and the numerical value is stored in the memory (21). Next, the movement amount from the origin Z31 to the origin Z32 is counted by the counter (22) in the control circuit as the A channel signal (3P pulse in this case), and the numerical value is stored in the memory (21).
Remember. Next, the amount of movement from the origin Z32 to the origin Z33 is counted by the counter (22) in the control circuit as the A channel signal (2P pulse in this case), and the numerical value is stored in the memory (21).
Remember. In this state, the numerical values obtained by moving the respective initial values set in the memory (21) in the control circuit and the arithmetic circuit (2
The comparison and determination is made in 3), and it is determined from the detected signal that the light has passed through the origin group slit Z3. Therefore, it is found that the point C is a position before the 2P pulse of the origin group slit Z3. With the above origin detection method, it is possible to detect the absolute position with a short distance of movement regardless of where the point C is.

Next, the case where point C is located in the origin slit group will be described. In this case, the interval 5P between the origin slit groups must be counted when counting the two origin signals. Therefore, when this 5P is counted, the absolute position can be detected by performing a control by the arithmetic circuit (23) so that the subsequent two origins can be counted. The same applies to the B channel, but since the B channel is used as a signal for determining the moving direction, detailed description thereof will be omitted.

When the power source is inserted and moved to the left side, the phase difference between the A and B channel signals is different. Therefore, even if the origin signals at the same 3P and 2P intervals are detected, they have passed through the origin group slit 2. It goes without saying that can be found.
Further, since the sum of the distances between the two origin slits in the origin group slit is 5P, it is possible to check that the detection is an erroneous detection due to external noise or the like when the number of signals more than this is counted. Further, since the distance between the origin group slits is 5P, if more pulses are counted, it can be checked that the detection error is due to external noise or the like.
In these cases, a highly reliable origin group slit can be detected by moving again and counting origin signals of other origin group slits.

Although the linear type incremental encoder has been described in the embodiment, it goes without saying that the absolute position (angle) can be detected in the same manner for the rotary type incremental encoder.

FIGS. 3 (a) and 3 (b) are views showing the structure of the combined origin slit when the origin slit width is narrow. FIG. 3A shows the slit of the origin detection signal and the detected waveform shape when the origin slit width is extremely narrow. When detecting high resolution, the slit width may be several microns, and if the origin slit is made up of one slit, the amount of light decreases and the origin detection signal does not reach the waveform shaping level and the origin output signal does not appear. The problem occurs. Therefore, as shown in FIG. 3B, an example of a method for detecting the origin signal by combining a plurality of slits having different slit widths to form an origin slit has been shown. In this case, since the amount of light passing through the slit is increased, an origin detection signal having a waveform shaping level or higher can be obtained and an origin signal can be obtained. This configuration is adopted as the origin slit of the conventional high-resolution type incremental encoder, and the origin slit configuration is complicated, but origin detection in the case of high resolution is possible. Although the present invention has been described with respect to the optical linear encoder, the same applies to magnetic, electromagnetic, and electrostatic encoders by changing the slit to the magnetic pole pitch or the electrode pitch, and is not limited to the optical encoder. Needless to say.

[0014]

As described above, according to the present invention, 3
The detection structure can be simplified by arranging two or more origin group slits and two or more origin group slits, each of which is made up of more than one origin slit, and making the origin slits that make up each origin group have different intervals. There is an effect that a simple absolute value encoder can be provided. Further, by making the intervals of the origin groups the same for each origin group, there is an effect that the absolute position detection method is simplified.

If the distance between the origin groups is determined from the beginning, it is checked whether the sum of the number of pulses between Z11 and Z12 and the number of pulses between z12 and Z13 matches the distance between the origin groups. There is also a check function to see if there is a false detection due to noise. Therefore, since it can be checked even if it is affected by external noise, there is an effect that the reliability can be improved as compared with the conventional simple absolute value encoder.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a simple absolute value encoder of the present invention.

FIG. 2 is a connection diagram showing the origin detection method of the present invention.

FIG. 3 is a diagram showing a configuration of a combination origin slit of the present invention.

FIG. 4 is a diagram showing a configuration of a conventional incremental encoder.

[Explanation of symbols]

1 scale 2 light emitting element 3 fixed side slit 4 light receiving element 5 waveform shaping circuit 6 origin slit 7 main slit 21 memory 22 counter 23 arithmetic circuit

Claims (6)

[Claims] 1. An absolute position detection encoder for detecting an absolute position from an incremental signal and an origin signal serving as a reference signal, comprising at least two origin groups configured to output at least three origin signals. An origin position signal group from the origin group has an absolute position detection function. 2. The absolute position detection encoder according to claim 1, wherein the intervals of the origin signal positions of the origin signal group are the same. 3. The absolute position detection encoder according to claim 1, wherein the origin signal groups are arranged at equal intervals. 4. The absolute position detection encoder according to claim 1, wherein the distance between the origin groups is larger than the distance between the origin signal positions in each origin signal group. 5. The absolute position according to any one of claims 1 to 4, wherein the origin signal is output from a detection unit composed of a slit, a magnetic pole or an electrode in which two or more are combined. Detection encoder. 6. In the absolute position detection encoder,
An origin detection method for an absolute position detection encoder, characterized in that the origin signal is detected by counting the intervals of the origin signal positions in each origin signal group.