JPS62232515A - Displacement detector - Google Patents

Abstract

PURPOSE:To detect the displacement position of an article to be measured with good accuracy, by selecting a sensor outputting a max. value signal from sensors outputting detection signals corresponding to the position of the article to be measured and outputting the code signal inherent to the selected sensor. CONSTITUTION:For example, in the case of a rotary encoder, the light emitted from a light emitting diode 6 is incident on an optical fiber 10 and subsequently incident to a photodiode 7-1. Even when the output light emitted from the optical fiber 10 is not condensed to one photodiode 7 but irradiates two or more photodiodes 7, the photodiode 7 max. in light receiving quantity is selected and the code signal inherent to the selected photodiode 7 is outputted. Because the interval between the photodiodes provided in a row can be made narrower than the width of the light emitted from the optical fiber 10, the photodiodes 7 can be arranged in a row in a state compressed at high density and quantity of rotation can be detected with high accuracy.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a displacement detection device that detects the amount of rotational or linear displacement of an object to be measured as an absolute value, and particularly relates to a displacement detection device that detects rotational or linear displacement of an object to be measured. This invention relates to a detection device.

[Technical background of the invention and its problems]

Conventionally, for example, a rotary encoder, which is a type of displacement detection device, has a digital pattern consisting of slits or openings shown as scratches in the figure at different radius positions at each predetermined center angle, as shown in FIG. A disc-shaped hood plate 401 is coaxially attached to a rotating shaft 400 held by a bearing 2 in the case 1 shown by the dashed line in the figure, and a detection unit 402 emits light from one side of the code plate 401 toward the digital button using a light source. The encoded absolute value of the rotation angle of the rotary shaft 400 is obtained as a digital signal by irradiating it and detecting the transmitted light with an optical sensor. In such a rotary encoder, in order to improve the resolution of the detected rotation angle, it is necessary to increase the number of digits of the digital pattern, which causes the problem that the diameter of the code plate 401 increases, making the device larger and more expensive. be. Furthermore, if the number of digits is increased by finely arranging the digital buttons in the radial direction on the code plate 401, the light source and the optical sensor in the detection unit 402 are required to have high precision.

[Purpose of the invention]

The present invention has been made in view of the problems of the prior art described above, and its purpose is to provide a compact displacement detection device that can quickly detect the displacement position of an object to be measured using an extremely accurate absolute value. It's about doing.

[Summary of the invention]

The present invention, which has been made to achieve the above object, includes a sensor that is arranged in a plurality of rows at predetermined intervals and outputs a detection signal according to the position of an object to be measured that moves along the row. a selection circuit that selects the sensor that outputs a detection signal with a maximum value from among the sensors, and a conversion circuit that converts the detection signal of the sensor selected by the selection circuit into a code signal unique to each sensor and outputs the signal. This is a displacement detection device characterized by comprising:

〔Effect of the invention〕

According to the present invention, the sensor that outputs the maximum value of the detection signal from among the sensors that output the detection signal according to the position of the object to be measured is selected by the selection circuit, and the conversion circuit selects the sensor that outputs the detection signal of the maximum value. Since the code signal of YES is output,
The displacement position of the object to be measured can be detected in absolute value with extremely high accuracy.

[Embodiments of the invention]

An embodiment of the present invention will be described in detail below with reference to the drawings. Note that the same parts are given the same reference numerals throughout the drawings.

One embodiment shown in FIGS. 1 to 4 is an example in which the present invention is applied to a rotary encoder. The structure of this embodiment is such that a case 1 consisting of a cylindrical outer shell shown by a dashed line in FIG. Rotating shaft 2 is bearing 3
It is held by the case 1 and inserted into the case 1.

Then, one end is attached to the tip of the rotating shaft 2 inside the case 1.
A rotating member 4, which is supported by and whose other end rotates around the axis of the rotating shaft 2, is fixed. A semiconductor chip 5 serving as a base is placed on the other end plane of the case 1, and a light emitting diode 6 serving as a light source is disposed on the semiconductor chip 5 at a portion where the fine points of the rotating shaft 2 intersect. On the semiconductor chip 5, a plurality of photodiodes 7, which are light-receiving elements, are arranged on the circumference around the light-emitting diode 6 so as to be located below the other end of the rotating member 4. That is, the optical fiber 10 is arranged in the lower part of the rotating member 4 on the side of the semiconductor chip 5 as shown in FIG.
The light emitted from the light emitting diode 6
Optical fiber 10 held by rotating member 4 facing upward
The light enters the photodiode 7.1 located below the optical fiber at the other end of the rotating member 4 facing above the photodiode 7.
sunlight enters. In this way, the detection signal of the photodiode 7.1 that has been incident is transmitted to each photodiode 7 as a unique digital signal via a circuit (not shown in FIG. 1) constructed on the semiconductor chip 5. is converted to

Hereinafter, a process in which the detection signal of the photodiode 7 is converted into a digital angle signal by the circuit will be explained in detail with reference to FIG. 3. On the semiconductor chip 5, a light emitting diode 6 is connected to a power source 301 (not shown) via a resistor and is lit.

The light emitted from this light emitting diode 6 is transmitted to the rotating member 4
The signal is transmitted through an optical fiber 10 fixed to the rotary member 4 and detected by a photodiode 7 located opposite the tip of the rotating member 4 . The light-receiving array 300 of the photodiodes 7 to which the input light has been received becomes conductive, and the current is input to the linear amplifier 8 from the DC power supply Vc through the light-receiving array 300 of the photodiodes 7 and is amplified. This linear amplifier 8 is provided for each photodiode 7 and is supplied with power from a DC power supply Vc.

The output signal of each linear amplifier 8 is inputted to two input terminals A and H of a comparator 9 together with output signals of other linear amplifiers 8 corresponding to adjacent photodiodes 7, respectively. The comparator 9 compares the intensities of the output signals of each linear amplifier 8 inputted to the two input terminals A and B, and outputs a positive voltage if the signal inputted to the input terminal A is larger than the input terminal B. If the signal input to input terminal B is larger than input terminal A, it is negative! Output the field. The output signal of each comparator 9 is inverted by an inverting amplifier 11 provided for each comparator 9.

The output signal of this inverting amplifier 11 is NANDed with the output signal of the comparator 9 whose input terminal is connected to the output terminal of the linear amplifier 8 to which the input terminal B side of the comparator 9 connected to each inverting amplifier 11 is connected. A NAND is performed in circuit 12. The output signal of the NAND circuit 12 is input to the control terminal of the amplifier 13 provided for each NAND circuit 12, and when O'' is input from the NAND circuit 12 to this control terminal, the amplifier 13 opens its gate and the near amplifier 8 The output terminal of each amplifier 13 is a diode 15 whose anode side is connected to a predetermined load resistor 14 among the load resistors 14 of n1l14 whose one end is connected to the DC power supply Vc. Each amplifier 13 is connected in a different connection state through the amplifier 13, and when the output voltage of the amplifier 13 becomes below 0, the load resistor 14 connected to the amplifier 13 through the diode 15 is connected to the amplifier 13 built-in wire. shorted to ground.

The input terminals of the NAND circuits 16 are connected to the other ends of the load resistors 14 whose one end is connected to the DC base iVc, and the negative logic signal obtained when the load resistors 14 are short-circuited is connected to the NAND circuit 16.
After being input to the D circuit 16, it is inverted and output as a positive logic signal to each terminal T, T, T3, . . . Tn.

In this embodiment, each terminal T, , T, , T,...
- A diode 15 is connected between each load resistor 14 and each amplifier 13 so that the positive logic signal output from Tn is output with a play code assigned to each photodiode 7.

Next, referring to a specific example, a description will be given of how a unique digital signal assigned to each photodiode 7 is output from the circuit formed on the semiconductor chip 5 described above.

When the rotating shaft 2 rotates together with the rotating member 4 in conjunction with the rotation of the object to be measured, the rotating member 4 rotates around the rotating shaft 2 within the case 1 at a position facing the semiconductor chip 5 . The light output from the light emitting diode 6 is sequentially irradiated by the optical fiber 10 fixed to the member 4 onto the light receiving array 300 of individual photodiodes arranged on the circumference.

For example, when the member 4 stops rotating and the photodiodes 7-2 to 7-3 detect light, each photodiode 7-1
．． The light-receiving array 300 of 7-2.7-3 becomes conductive, and current is supplied from the DC power supply Vc to each linear amplifier 8-1.8-2.8-3 via each light-receiving array 300. The output signals of the linear amplifiers 8-1.8-2, 8-3 are input to the input terminals of the comparators 9-2.9-3.9-4, respectively, and are input to the input terminals of the comparators 9-1. 9-2.9-
It is input to input terminal B of No. 3. At the input terminal of comparator 9-1, there is a photodiode 7- which is not detecting light.
Since the output signal of the linear amplifier 8-0 connected to 1 is input, the light-receiving area of the light-receiving array 300 of each photodiode 7-1 and 7-2 is linear because the photodiode 7-2 is larger. Since the current value output from amplifier 7-2 exceeds that of linear amplifier 7-1, comparator 9-1 determines that the current value applied to input terminal A is higher than that of linear amplifier 7-1.
outputs a negative voltage. Similarly, since the light receiving area of each light receiving array 300 of the photodiodes 7-2 and 7-3 is larger in the photodiode 7-3, the comparator 9-2 outputs a negative voltage. Further, the light receiving area of each light receiving array 300 of the photodiode 7-3.7-4 is larger for the photodiode 7-3, and the light receiving area of each light receiving array 300 of the photodiode 7-4.7-5 is larger than that of the photodiode 7-3. -4 is larger, so the filters 9-3, 9-4 each have a positive fiE
Outputs E. Comparator 9-1. 9-2.9-3
゜All fan parators 9 other than 9-4 have both input terminals AB.
Since the input current values are balanced, neither positive nor negative voltage is output. The inverting amplifier 11-2, which receives the negative voltage from the humpator 9-2, outputs a positive voltage and performs a NAND
Input to circuit 12-2.

The NAND circuit 12-2 performs a NAND between the positive 11EE output from the comparator 9-3 and the positive voltage output from the inverting amplifier 11-2, and outputs a "0" signal. Since the "0" signal output from the NAND circuit 12-2 is input to the control terminal of the amplifier 13-2, the gate is opened and the output signal consisting of the positive voltage of the linear amplifier 8-2 is inverted and output to the output terminal side. Let be a negative voltage. Load resistance 14-1.14
-2.14-3°..., diode 1 of 14-H
A load resistor 14” is connected to the amplifier 13-2 via the
-2, 14-n, current flows from the DC power supply Vc, but the other load resistor 14 is connected to the amplifier 13-2 through the diode 15.
Since it is not connected to the DC power source Vc, no current flows from the DC power source Vc. Therefore, each NAND circuit 16 receives a negative logic signal in each NAND circuit 16-1.16-2.16-3, .
1, 0, 1 for every 16-n, respectively. . . , 0" is input. Each NAND circuit 16 receives the input negative logic signal "
1.0.1...0" is inverted and a positive logic signal "0.
1.0・1"i output to each leakage T,, T1.T,...Tn. All other amplifiers 13 except amplifier 13-2 output the output of the NAND circuit 12 connected to the control terminal. Since the signal is 1'', the gates do not open, and the outputs id of these amplifiers 13 are all positive voltages. Therefore, all amplifiers 13 other than amplifier 13-2 do not short-circuit the load resistor 14.

In this way, in the rotary encoder of this embodiment, even if the output light projected from the optical fiber 10 is not focused on one photodiode 7 but is projected across two or more photodiodes 7, The photodiode 7 that receives the most amount of light is selected and the selected photodiode 7
A unique code signal is output. Therefore, the interval between the photodiodes 7 arranged in a row can be made narrower than the width of the irradiated light from the optical fiber 10, so the photodiodes 7 can be arranged in a row in a more densely compressed manner, and rotation with higher precision can be achieved. Quantity can be detected.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the configuration of essential parts of the embodiment, and FIG. 3 is a circuit diagram showing a circuit used in the embodiment. , FIG. 4 is a perspective view showing a conventional example. 1... Case, 2... Rotating shaft, 3... Bearing, 4...
...Rotating member, 5...Semiconductor chip, 6...Light emitting diode, 7...Photodiode. Figure 1 Figure 2

Claims (1)

[Claims] A sensor that is arranged in a plurality of rows with a predetermined interval and outputs a detection signal according to the position of the object to be measured moving along the row, and the sensor that outputs the detection signal of the maximum value from among the sensors. 1. A displacement detection device comprising: a selection circuit that selects a sensor; and a conversion circuit that converts a detection signal of the sensor selected by the selection circuit into a code signal unique to each sensor.