JP3103266B2 - Absolute position detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device, and more particularly to an absolute position detecting device.

[0002]

2. Description of the Related Art As a conventional absolute position detecting device, an absolute position detecting device using a gray code is well known. You need a truck. Therefore, there is a disadvantage in that the number of tracks increases when an attempt is made to increase the resolution, and the device becomes large-scale.

Therefore, an absolute position detecting device using an N-bit binary pseudo-random number sequence as an absolute position detecting device capable of detecting an absolute position even if the number of tracks is one, that is, all N-bit (N is an integer) patterns in a pattern By using different pseudo-random number sequence patterns on one track,
There is an absolute position detection device that calculates the absolute position of the detected object by detecting this pattern. FIG. 4 is a schematic diagram showing an example of such a conventional absolute position detecting device of the pseudo random number sequence pattern system. Here, the disk (2) attached to the detection target (1) is a disk made of a magnetically permeable material, and has a notch on the outer periphery thereof. Is formed. Assuming that the notched portion is 0 and the uncut portion is 1, 4-bit detection is performed in this example, and the pseudo random number sequence bit pattern is 001001111011.
Since 00101 is used, the disk has a shape like a disk (2) in the same figure, and the relationship between each pattern and the absolute position information is as shown in FIG.

The sensor group is a semiconductor magnetic sensor (3a, 3b, 3c, 3d) having a permanent magnet (not shown).
The binarizing means (5) uses the comparison circuit (20) to output signals (S1, S2) of the semiconductor magnetic sensors (3a, 3b, 3c, 3d).
2, S3, S4) and a predetermined voltage level (V1) are binarized to detect a 4-bit pseudo random number pattern. The position information converting means (8) comprises a CPU, a RAM, a ROM storing the relationship between the 4-bit pseudo-random pattern and the absolute position shown in FIG. 6, and the like, and the CPU according to the relationship shown in FIG. Absolute position information is detected from a pseudo random number pattern of bits (Japanese Patent Laid-Open No. 4-110727).
No., JP-A-4-136715).

[0005]

However, in such a conventional absolute position detecting device, an erroneous detection may occur near a change point of a bit pattern. That is, as shown in FIG. 7, when the processing accuracy of a certain portion of the disk (2) is poor (the portion indicated by an ellipse in the drawing), the output signal level of the sensor (the sensor 4 in the drawing)
The black level of the output level of d is different from the original level (white circle of the output level of the sensor 4d in the figure). Therefore, when the sensor group is near the changing point of the bit pattern, the pattern to be detected is 0010. In fact, the pattern actually becomes 0011, and the position information becomes incorrect. The present invention has been made in order to solve such a problem, and according to the present invention, even when the sensor group is near the changing point of the bit pattern, erroneous detection is not performed, so that it is possible to always detect an accurate position. A position detecting device capable of being provided is provided.

[0006]

According to the present invention, an object to be detected having a pattern in accordance with an N-bit binary pseudorandom number sequence (N is an integer) in which all N bits on one track have different patterns, A first sensor group for detecting an N-bit binary pseudo-random number of the detected object; and a second sensor group for detecting an N-bit binary pseudo-random number of the detected object at a phase different from that of the first sensor group. , A binarizing means for binarizing the outputs of the first and second sensor groups, and any one of the signals of the first sensor group being up and down around a binarized reference voltage A signal level change point detecting means for detecting whether or not the voltage is within a voltage of a fixed width; and the signal level change point detecting means, wherein one of the signals of the first sensor group detects the binarized reference voltage. When it is detected that the voltage is within a voltage having a constant vertical width at the center, the second When the binarized signal of the sensor group is output and it is detected that the voltage is not within a voltage having a constant upper and lower width around the binarized reference voltage, the binarized signal of the first sensor group is output. This is achieved by providing a sensor signal selecting means for outputting a signal, and position information converting means for converting the binarized signal output from the sensor signal selecting means into position information of the detected object.

[0007]

According to the present invention, the signal of the sensor group which is not in the vicinity of the binarized reference voltage among the first sensor group and the second sensor group is selected and used. Accurate position can be detected.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a first embodiment of the absolute position detection device of the present invention in correspondence with FIG. 4, and the same components are denoted by the same reference numerals. The disk (2) attached to the object to be detected (1) is exactly the same as the conventional one, so that the description is omitted. The first sensor group (3a to 3d) has the same configuration as the sensor group described in the conventional example, and the arrangement of each sensor is mounted in the same manner as in the conventional example. The second sensor group (4a-
4d) has the same configuration as that of the first sensor group (3a to 3d), except that any magnetic sensor is attached at a fixed distance (x1) from the first sensor, and the phase of the signal to be detected is This is different from the first sensor group (3a to 3d). In the example of FIG. 1, x1 is a quarter of the 1-bit length of the binary pseudorandom number sequence of the detection target, and the first sensor group (3a
3d) and the signal of the second sensor group (4a-4d) have a phase difference of 90 degrees.

The signal level change point detecting means (7) is shown in FIG.
And the voltage level determination circuit (21) determines that the voltage of each signal of the first sensor group (3a to 3d) is V2 (V
1-Vx) to V3 (V1 + Vx) when High
Output, otherwise it is Low output. The NOR circuit (22) has a low output when at least one of the outputs of the four voltage level determination circuits has a high output, and has a high output when all four comparison circuits have a low output. The sensor signal selecting means (8) outputs the binarized signals of the first sensor group (3a to 3d) when the output of the signal level change point detecting means (7) is High, and outputs the signal level change. When the output of the point detection means is a Low output, the second
Output the binarized signals of the sensor groups (4a to 4d). The position information converting means (9) converts the pattern of the N-bit binary pseudorandom number sequence, which is the output signal of the sensor signal selecting means, into absolute position information in accordance with the conversion table of FIG. I do.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, first, the sensor signal selecting means (11) determines whether the signal of the first sensor group (3a to 3d) is the second signal or not. The configuration is such that signals from the sensor groups (4a to 4d) are selected, and then binarization is performed. Since the specific contents of each constituent block are the same as those in the above-described embodiment, details are given. Is omitted.

In the above embodiment, the signal level change point detecting means (7) and the sensor signal selecting means (8) are both constituted by hardware processing, but the present invention is not limited to this. No, CPU of position information conversion means,
In addition to ROM and RAM, analog-to-digital converter (A
D converter) or the like, and may be performed by software processing. Further, the pattern of the pseudo-random number in the present invention is not limited to the above-described example of 4 bits, but may be another bit number. Further, the pseudo-random number sequence means and the sensor group only need to generate the above-described pseudo-random number sequence pattern. For example, the pseudo-random number sequence pattern is recorded on a magnetic material, and the magnetic sensor detects the pseudo-random number sequence pattern. A so-called magnetic drum type or an optical type may be used. Further, the portion for generating the pseudo-random number sequence (the disk (2) in the above-described embodiment) is not particularly limited to a rotary type, but may be a linear type or another type.

[0012]

As described above, according to the absolute position detecting device of the present invention, an accurate absolute position can be always detected. Moreover, in the present invention, since the condition for determining whether to switch between the first sensor group and the second sensor group is detected from the signal itself of the first sensor group, a special condition is required for detecting the signal for switching. Since no sensor or pattern is required, the size and cost of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing a first embodiment of an absolute position detection device according to the present invention.

FIG. 2 is a diagram schematically showing a signal level change point detecting means of the device of the present invention shown in FIG. 1;

FIG. 3 is a configuration diagram schematically showing a second embodiment of the absolute position detection device according to the present invention.

FIG. 4 is a schematic configuration diagram illustrating an example of a conventional absolute position detection device.

FIG. 5 is a diagram illustrating a relationship between a pseudo random number pattern and an absolute position.

FIG. 6 is a diagram showing an input / output relationship in a position information conversion unit.

FIG. 7 is a diagram for explaining erroneous detection in a conventional absolute position detection device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Detected object 2, disk 3a, 3b, 3c, 3d, 4a, 4b, 4c, 4d Magnetic sensor 5 Binarization means 7 Signal level change point detection means 8, 11 Sensor signal selection means 9 Position information conversion means 20 Comparison circuit 21 Voltage level determination circuit 22 NOR circuit

Claims (2)

(57) [Claims] 1. An object having a pattern according to an N-bit binary pseudorandom number sequence (N is an integer) in which all N bits on one track have different patterns; First to detect binary pseudorandom numbers
And N of the object to be detected at a phase different from that of the first sensor group.
A second sensor group for detecting a binary pseudo-random number of bits; a binarizing unit for binarizing the outputs of the first and second sensor groups; and any one of the signals of the first sensor group Signal level change point detecting means for detecting whether or not the signal is within a voltage having a constant upper and lower width around a binarized reference voltage; and wherein the signal level change point detecting means detects each signal of the first sensor group. Is detected to be within a voltage having a constant upper and lower width around the binarized reference voltage.
Output a binarized signal of the first sensor group, and when detecting that the voltage is not within a voltage having a constant upper and lower width around the binarized reference voltage, the first sensor group is binarized. Characterized by comprising: sensor signal selecting means for outputting a detected signal; and position information converting means for converting a binarized signal output from the sensor signal selecting means into position information of the object to be detected. Position detection device. 2. An object to be detected having a pattern according to an N-bit binary pseudorandom number sequence (N is an integer) in which all N bits on one track have different patterns; First to detect binary pseudorandom numbers
And N of the object to be detected at a phase different from that of the first sensor group.
A second sensor group for detecting a binary pseudo-random number of bits, and whether or not any of the signals of the first sensor group is within a voltage having a constant upper and lower width around a binarized reference voltage. The signal level change point detecting means for detecting, and the signal level change point detecting means, wherein any one of the signals of the first sensor group is within a voltage having a constant upper and lower width around the binarized reference voltage. Is detected, the second
Sensor signal selecting means for outputting a signal of the first sensor group when outputting a signal of a sensor group of the first group and detecting that the voltage is not within a voltage having a constant upper and lower width around the binarized reference voltage. A binarizing unit for binarizing each signal output from the sensor signal selecting unit, and position information conversion for converting the binarized signal from the binarizing unit into position information of the object to be detected. Means for detecting an absolute position.