JPH0560575A - Position detection unit - Google Patents

Abstract

PURPOSE:To enable position detection of high resolving power using small and simple constitution by computing a position from the distance between two indexes detected and from the number of pulses generated from a clock circuit during detection of the indexes. CONSTITUTION:A light sensor 3 detects the index 2a of a scale 1 and starts counting pulses generated by a clock circuit 4. When the sensor 3 detects the index 2b the number of pulses generated from the circuit 4 from when the index 2a is detected to when an index 2b is detected is detected. At this time the amount of movement of the scale 1 equal to one count of a clock pulse is calculated by a processing circuit 5. Next when the sensor 3 detects an index 2c the number of pulses generated from the circuit 4 from when the index 2b is detected to when the index 2c is detected is detected. The distance over which the scale 1 moves past the index 2b to the index 2c is found by the processing circuit 5.

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 for detecting the position of a moving member and calculating the moving speed and moving amount of the member.

[0002]

2. Description of the Related Art An encoder has been known as an optical position detecting device. This encoder moves a linear or disk-shaped scale between a light-emitting diode and a light-receiving IC, which are arranged opposite to each other, and projects light on a light-transmitting portion and a light-shielding portion provided at equal intervals on the scale. Then, the light receiving IC emits an ON-OFF signal.

[0003]

However, in the conventional position detecting device configured as described above, the scale movement is performed by counting the pulses generated when the scale moves between the light emitting / receiving members. It is designed to measure distance. Therefore, in order to obtain the moving speed of the scale, it is necessary to count the pulse signals generated during a certain fixed time. Further, even when the scale is moving at a constant velocity or a velocity close to the constant velocity, in order to improve the position resolution, the pitch of the light-transmitting portion and the light-shielding portion provided on the scale is made finer, and the The optics must be improved. Therefore, there is a problem that the structure becomes complicated, the device becomes large, the number of parts increases, and the cost becomes high.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a small position detecting device capable of easily measuring a speed with a simple structure and detecting a position with high resolution. ..

[0005]

A position detecting device of the present invention comprises a scale in which indexes are provided at equal intervals, a detecting means for photoelectrically detecting the indexes, and a clock circuit for electrically generating a high-speed pulse. And a calculating means for calculating the moving speed and the moving amount of the scale from the distance between the two indexes detected by the detecting means and the number of pulses generated by the clock circuit between them.

[0006]

In the position detecting device having the above-mentioned structure, the indexes provided at equal intervals on the scale are photoelectrically read by the detecting means, and the operation is performed by using the pulse generated by this reading and the pulse generated by the clock circuit. The moving speed and moving amount of the scale can be detected by the means.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the position detecting device of the present invention will be described below with reference to the drawings.

1 and 2 show the configuration of a first embodiment of the present invention. In FIG. 1, a plurality of, for example, four indexes 2 are provided radially at equal intervals on a disk-shaped scale 1. The scale 1 is formed of a translucent member, and the index 2 is formed of a member that reflects light. Further, the scale 1 rotates in conjunction with a member to be measured (not shown). Index 2 on scale 1
An optical sensor 3, which is a detection means composed of a light emitting member and a light receiving member (not shown), is provided on the rotation locus of the light. The light emitted from the light emitting member is reflected by the index 2 and enters the light receiving member. There is. Further, the clock circuit 4 for measuring time generates high-speed electric pulses at regular time intervals. Further, the processing circuit 5, which is a calculation means,
The moving speed and the moving amount of the member to be measured are calculated by the pulses emitted from the optical sensor 3 and the clock circuit 4, respectively.

Next, the operation of this embodiment will be described with reference to FIGS. The rotation of the scale 1 causes the optical sensor 3 to generate a pulse signal having a waveform as shown in FIG. Further, the clock circuit 4 generates a pulse signal having an equidistant waveform as shown in FIG.

Next, the processing steps of position detection according to this embodiment will be described with reference to FIG. In step 101, the optical sensor 3 detects the first index 2a of the scale 1.
To detect. At the same time, in step 102, counting of pulses generated from the clock circuit 4 is started. Next, in step 103, when the optical sensor 3 detects the second index 2b of the scale 1, step 104
At the second index after detecting the first index 2a
The number of pulses n ₁ generated from the clock circuit 4 until the index 2b of is detected is detected. At this time, in step 105, the processing circuit 5 calculates the movement amount ΔL of the scale 1 for one clock pulse count.

Here, the distance L between the indexes 2a and 2b
_{Since 1} is constant and known, ΔL = L ₁ ÷ n ₁ to ΔL
Can be easily calculated. Next, in step 106, when the optical sensor 3 detects the third index 2c of the scale 1, in step 107, the clock circuit 4 from the detection of the second index 2b to the detection of the third index 2c. The number of pulses n ₂ generated from the sensor is detected. Then, in step 108, the moving distance L ₂ of the scale 1 that passes through the second index 2b and reaches the third index is ΔL × by the processing circuit 5.
It can be obtained by calculating n ₂ .

Thereafter, by repeating the same processing,
The moving distance from when the scale 1 starts moving to when the scale 1 stops is determined by the number n of pulses generated from the clock circuit 4,
It can be obtained by the calculation of L _Xn . Position control can also be performed by the number of pulses n generated from the clock circuit 4.

According to this embodiment, it is possible to easily measure the moving speed of the member to be measured and to detect the position with high resolution by a small device having a simple structure.

4 and 5 show the configuration of the second embodiment of the present invention. In these figures, parts corresponding to those of the first embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted as appropriate. In this embodiment, the scale 11 is linear. Indexes 2 are provided on the surface of the plate-like scale 11 at equal intervals, and two optical sensors 3 for index detection, 3a and 3b, are provided. The distance between the optical sensors 3a and 3b is different from the distance of the index 2. FIG. 5 (a),
(B) and (c) show a signal pulse when the two optical sensors 3a and 3b detect the index 2 and a pulse generated by the clock circuit 4, respectively.

In the present embodiment, the time from the detection of one index 2 by the optical sensor 2a until the detection of the index 2 by the optical sensor 2b is performed by counting the number of pulses generated by the clock circuit 3. Can be found at. Since the interval of the index 2 is known, the moving speed of the scale 11 can be easily obtained, and the moving amount of the index 2 due to the moving of the scale 11 should be calculated by the moving speed of the scale 11 and the number of pulses generated by the clock circuit 3. You can

FIGS. 6 and 7 show a third embodiment of the present invention. As shown in FIG. 6, this embodiment is composed of an input pen 21 and a scanner body 22, and an image reading head 23 and a position detection device 24 are provided at the tip of the input pen 21. As shown in FIG. 7, the image reading head 23 comprises a lens 25 and a CCD 26, and the position detecting device 24 comprises a roller 28 having an index 27 on its surface and an optical sensor 29 for detecting the index 27. There is. The rotation axis of the roller 28 is the lens 27.
And parallel to the CCD 26.

In the present embodiment, a person holds the input pen 21 and runs on the member to be measured via the roller 28, and C
The CD 26 detects the positions of two points on the member to be measured, and the index 27 on the roller 28 is set between the optical sensors 29 during the detection.
Detected by the number of pulses of 2
Read the amount of movement between points.

According to this embodiment, it is possible to calculate, for example, the size of the image formed on the member to be measured with a small device. This is particularly effective when the input pen 21 is moved in one direction at a constant speed and a low speed.

[0019]

As described above, according to the position detecting device of the present invention, the pulse emitted from the detecting means for detecting the indexes provided at equal intervals on the scale and the pulse emitted from the clock circuit are used. Since the moving speed between the indexes is calculated and the moving amount of the scale is estimated based on this moving speed and the number of pulses generated from the clock circuit, the moving speed of the measured member can be easily made by a small device with a simple configuration. Measurement can be performed, and position detection can be performed with high resolution.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing a configuration of a first embodiment of a position detecting device of the present invention.

FIG. 2 is a waveform chart of a pulse emitted from each part of FIG.

FIG. 3 is a flowchart illustrating the operation of the first embodiment.

FIG. 4 is a functional block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 5 is a waveform diagram of pulses generated by each part of FIG.

FIG. 6 is a perspective view showing a configuration of a third exemplary embodiment of the present invention.

7 is an explanatory diagram showing a configuration of a tip portion of the input pen of FIG.

[Explanation of symbols]

 1 scale 2 index 3 optical sensor (detection means) 4 clock circuit 5 processing circuit (calculation means)

Claims (1)

[Claims] 1. A scale in which indexes are provided at equal intervals, a detecting means for photoelectrically detecting the indexes, a clock circuit for electrically generating a high-speed pulse, and a space between two indexes detected by the detecting means. A position detecting device for calculating the moving speed and the moving amount of the scale from the distance of 1 and the number of pulses generated by the clock circuit between them.