JPH04329368A - Rotation detecting device - Google Patents

Abstract

PURPOSE:To detect the rotating speed over a wide measurement range. CONSTITUTION:The first and second radiated patterns 41, 42 made of slits 41a, 42a with different radiation areas are formed on a disk 40 rotated by a motor 30, and optical sensors 51, 52 corresponding to the radiated patterns 41, 42 are switchably provided. Light is fed to a light receiving element 51b via the slit 41a with a smaller slit area at the low-speed rotation. The optical sensor 51 is switched to the optical sensor 52 at the high-speed rotation, and light is fed to a light receiving element 52b via the slit 42a with a larger slip area. The light reception quantity of the light receiving element 51b and the light receiving element 52b are made constant at the low-speed rotation and high-speed rotation, thus stable electric signals S51, S52 are outputted.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation detection device that uses a disk to detect the rotation speed of a rotating body such as a motor.

0002

[Prior Art] Conventionally, technologies in this field include:
For example, there was one shown in FIG. The configuration will be explained below using figures.

FIG. 2 is a schematic configuration diagram showing an example of the configuration of a conventional rotation detection device.

This rotation detection device measures the rotation speed of a rotating body, for example, a motor 1.
A disk 10 is attached to the shaft 1a. A slit row 11 is formed on the disk 10 as a pattern to be irradiated. The slit row 11 is constructed by arranging a certain number of slits 11a on the disk 10.

Optical sensors 20 are installed above and below the disk 10.
is provided. The optical sensor 20 includes a slit row 11
It has a light emitting element 21 that irradiates light to the light emitting element 21 and a light receiving element 22 that converts the light emitted from the light emitting element 21 into an electric signal S22. A power source 23 is connected to the input side of the light emitting element 21, and a signal processing circuit 24 is connected to the output side of the light receiving element 22.

The signal processing circuit 24 inputs the electric signal S22 output from the light receiving element 22, converts intermittent changes in the electric signal S22 into a pulse signal based on the detection level TH1, and detects the rotation speed V1. It is something to do.

In this rotation detecting device, the light emitting element 21 lights up when power is supplied from the power source 23, and the slit row 11
irradiate light on. By rotating the disk 10,
Light from the light emitting element 21 passes through the slit 11a and intermittently enters the light receiving element 22. The light receiving element 22 converts the incident light into an electrical signal S22 and outputs it to the signal processing circuit 24. In the signal processing circuit 24, the input electric signal S22
is converted into a pulse signal proportional to the rotation speed, and the number of pulse signals is counted for a certain period of time to output the rotation speed V1 of the motor 1.

[0008]

SUMMARY OF THE INVENTION However, the conventional rotation detecting device has the following problems.

FIGS. 3(a) and 3(b) are output waveform diagrams of the optical sensor in FIG. 2, where (a) is the waveform at low speed rotation;
(b) shows the waveform during high speed rotation. Furthermore, (a
) and (b) are output waveform diagrams of the optical sensor when the opening area of the slit is increased, in which (a) shows the waveform during high-speed rotation, and (b) shows the waveform during low-speed rotation.

As shown in FIGS. 3A and 3B, at low speed rotation, the light receiving element 22 can receive a constant amount of light and outputs an electrical signal S22 of a detection level TH1 or higher. However, in the case of high-speed rotation, since the opening area of the slit 11a on the disk 10 is constant, the light receiving element 2
2 decreases, and the output of the light receiving element 22 decreases. In the signal processing circuit 24, the number of slits 11a cannot be calculated if the output is small below the detection level TH1.

Therefore, in order to solve this problem, if the opening area of the slit 11a is made larger in accordance with the high speed rotation, the amount of light passing through the slit 11a can be increased, and the output of the light receiving element 22 will be increased. , slit 1
The number of 1a can be calculated. However, by forming the opening area of the slits 11a to be large, the number of slits 11a in the slit row 11 decreases, which makes it difficult to detect minute rotations on the low-speed rotation side, as shown in FIG. 4(b). . For this reason, it was not possible to cope with low-speed rotation and high-speed rotation, and a satisfactory rotation detection device could not be obtained.

[0012] The present invention addresses the problems that the prior art had, in that the amount of light received by the light receiving element decreases at high speed rotation, making it impossible to calculate the number of slits, and that increasing the aperture area of the slits reduces the number of slits. The present invention provides a rotation detection device that solves the problem of difficulty in detecting minute rotations.

[0013]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the first invention provides a disk which is rotated by a rotating body and has an irradiation pattern formed of a plurality of irradiation parts arranged on a circumference. , an optical sensor having a light emitting element that irradiates light onto the irradiated part using drive power and a light receiving element that converts the light from the irradiated part into an electrical signal, and converts the output of the light receiving element into a pulse signal. The rotation detecting device detects the rotational speed of the rotary body by converting the pulse signals and counting the number of pulse signals, which takes the following measures.

That is, the irradiated area of the irradiated area is set to a size that allows the light receiving element to receive a predetermined amount of light in accordance with the measurement range of the rotational speed of the rotating body, and An optical sensor in which a plurality of types of irradiation patterns consisting of irradiation areas are formed on one or more disks rotated by the rotary body, and which can be switched by a switching means according to the plurality of types of irradiation patterns. It has multiple .

[0015] In a second invention, the switching means of the first invention determines the rotational speed measurement range of the disk by comparing a determination level set according to the measurement range with an output level of the optical sensor. It is composed of a judgment circuit such as a comparator that makes a judgment and outputs a control signal according to the measurement range, and a switching circuit such as a gate circuit that switches either each input or output of the optical sensor based on the control signal. It is.

[0016] In a third aspect of the invention, the irradiated portion of the first aspect is constituted by a slit or a reflective groove.

[0017] In a fourth invention, the irradiated portion of the second invention is constituted by a liquid crystal element whose transmission area of light from the light emitting element can be varied based on the control signal.

[0018] A fifth invention is such that the control signal of the fourth invention is generated externally by a receiving means such as a non-contact type solar battery.

[0019]

[Operation] According to the first invention, since the rotation detecting device is configured as described above, the light receiving element receives an electric current that changes depending on the number of irradiated portions formed on the disk and the rotational speed of the rotating body. It works to output a signal. Here, the irradiated part is
The irradiation area is set to a size that allows the light receiving element to receive a predetermined amount of light in accordance with the measurement range of the rotational speed of the rotating body. A plurality of types of irradiation patterns including such irradiation areas are formed on the disk, and a number of optical sensors corresponding to the irradiation patterns are switchably provided. When the measurement range is to be rotated at a high speed or a low speed, for example, the switching means operates to switch the optical sensor to an irradiation pattern corresponding to the rotational speed of the rotating body. The irradiated area of each irradiated pattern differs depending on the measurement range, so even if the rotation speed of the rotating body changes, for example, from low speed to high speed, the amount of light received by the light receiving element will vary. is constant, the number of parts irradiated by the optical sensor can be calculated, and conversion into a pulse signal can be performed reliably.

According to the second invention, the optical sensor of the first invention is switched by a control signal. That is, in the determination circuit, when the rotational speed of the rotating body changes and the amount of light received by the light receiving element decreases or increases, the output of the light receiving element reaches the determination level of the comparator, for example, and a control signal is generated. . This control signal is sent to the switching circuit. In the switching circuit, for example, when a control signal is input to one of the gate circuits connected to the optical sensor, the gate circuit turns on and off to switch the optical sensor.

According to the third invention, since the irradiated portion is constituted by a slit or a reflective groove, the slit or reflective groove can be easily detected by an optical sensor.

According to the fourth aspect of the invention, the irradiated portion is composed of a liquid crystal element, and the size of the transmission area can be varied. The transmission area is changed using the control signal of the second invention. Therefore, only one optical sensor is required and the structure is simple.

According to the fifth aspect of the invention, a control signal from the outside is converted into an output voltage of a solar cell or the like. In this way, control signals can be exchanged without contact, and changes in the transmission area of the liquid crystal element can be controlled. Therefore, the above problem can be solved.

[0024]

First Embodiment FIG. 1 is a schematic diagram showing an example of the configuration of a rotation detecting device according to a first embodiment of the present invention, and FIG. 5 is a perspective view of a disk in FIG. 1.

This rotation detection device measures the rotation of a rotating body, for example, a motor 30. As shown in FIG. 5, a disk 40 is attached to the shaft 30a of the motor 30.

On the disk 40, a first slit row 41, which is an irradiated pattern, consisting of slits 41a, and a second slit row 42, consisting of slits 42a, are formed on the circumference. The incident area of the slit 41a is, for example,
The incident area of the slit 42a is set to be smaller than the incident area of the slit 11a shown in FIG. 2, and the incident area of the slit 42a is set to be larger than the incident area of the slit 11a. Further, the numbers of slits 41a and 42a are respectively the same as those in the first slit row 4.
The first and second slit rows 42 are different.

As shown in FIG. 1, first and second transmission type optical sensors 51 and 52 are provided on the front and back surfaces of the disk 40. The optical sensor 51 transmits light to the slit array 41.
It has a light emitting element 51a that emits light upward, and a light receiving element 51b that receives light emitted from the light emitting element 51a and outputs an electric signal S51, and detects the slit 41a. Similarly, the optical sensor 52 includes a light emitting element 52a that irradiates light onto the slit array 42 and a light receiving element 52b that receives the light emitted from the light emitting element 52a and outputs an electrical signal S52.
, and detects the slit 42a.

In the optical sensor 51, the input side of the light emitting element 51a is connected to the drive power source 70 via the switching means 60, and the output side of the light receiving element 51b is connected to the signal processing circuit 80 via the switching means 60. . Similarly, in the optical sensor 52, the input side of the light emitting element 52a is connected to the switching means 60.
The output side of the light receiving element 52b is connected to a signal processing circuit 80 via a switching means 60.

The switching means 60 includes optical sensors 51 and 52.
The judgment circuit 60a and the switching circuit 6
0b. The determination circuit 60a includes a first comparator 61 to which the output of the light receiving element 51b is input, and a second comparator 62 to which the output of the light receiving element 52b is input. The comparator 61 compares the output of the light receiving element 51b with the determination level (
A control signal Sa is output by comparing the threshold value (threshold value) TH11. Similarly, the comparator 62 compares the output of the light receiving element 52b with a determination level (threshold value) TH12, and outputs a control signal Sb.

The switching circuit 60b includes first and second AND gates (hereinafter referred to as AND gates) 63 and 64, and third and fourth AND gates 65 and 66. The first AND gate 63 ANDs the output of the comparator 61 and the output of the light receiving element 51b, and outputs the output of the light receiving element 51b directly to the signal processing circuit 80. The third AND gate 65 connects the power source 70 for driving the light emitting element and the input side of the light emitting element 51a based on the outputs of the comparators 61 and 62. Similarly, the second AND gate 64 logically ANDs the output of the comparator 62 and the output of the light receiving element 52b, and outputs the output of the light receiving element 52b directly to the signal processing circuit 80. The fourth AND gate 66 connects the power source 70 and the input side of the light emitting element 52a based on the output of the comparator 61.

[0031] The signal processing circuit 80 processes electrical signals S51, S
52 with a detection level (threshold) Vth, and shapes and clips the obtained waveform.
and a counter 82 that counts the number of pulse signals P generated by the pulse generation circuit 81 for a certain period of time, and outputs the rotational speed V11 to an output terminal 83. In addition, in the slit rows 41 and 42, the slit 41a
, 42a are different, the number of pulse signals counted by the counter 82 is also different, but this is adjusted by changing the opening/closing interval of the gate.

Next, the operation of this rotation detection device will be explained with reference to FIG.

FIG. 6 is an output waveform diagram of the optical sensor in FIG. 1, in which (a) to (d) show the transition of rotation speed from low speed rotation to high speed rotation, and (e) to (g) show the transition of rotation speed from low speed rotation to high speed rotation. It shows the transition of rotational speed from rotation to slow rotation.

When the motor 30 rotates at low speed, the disk 4
0 also rotates at the same speed. The light emitting element 51a is
Power is supplied from the drive power source 70 to irradiate light onto the slit array 41 of the disk 40 . The light that has passed through the slit 41a is incident on the light receiving element 51b, and is converted into an intermittent electric signal S51 (FIG. 6(a)). In the judgment circuit 60a, since the output of the light receiving element 51b exceeds the judgment level TH11, the output of the comparator 61 is logic "H", and the output of the light receiving element 51b is passed through the AND gate 63 to the pulse generating circuit 81. is input to. In the pulse generation circuit 81, the output level and detection level (threshold) V of the electric signal S51
After comparing th and th, the waveform is shaped and clipped to generate a pulse signal P. The counter 82 counts the number of pulse signals P generated by the pulse generation circuit 81 for a certain period of time. And the output terminal 83 has
The rotational speed V11 of the motor 30 is output.

When the rotational speed of the motor 30 changes to high speed rotation, the time during which light is incident on the light receiving element 51b also becomes shorter. Therefore, the amount of light passing through the slit 41a decreases,
The output of the light receiving element 51b becomes smaller (Fig. 6(b), (c)
)). Further, when the motor 30 rotates at high speed, the output of the light receiving element 51b is at the judgment level TH11 of the judgment circuit 60a.
(FIG. 6(d)), and the output of the comparator 61 becomes “
The output of the AND gate 66 becomes "H". Since the output of the AND gate 65 is "L", the drive power supply 70
is connected to the input side of the light emitting element 52a, and the optical sensor 52
A switch is made to

Since the slit 42a is set to have a larger incident area than the slit 41a, the light receiving element 52b
The amount of light received is constant as in the case of low speed rotation, and the output of the light receiving element 52b is sent to the signal processing circuit 80 via the AND gate 64. And the output terminal 83 has
The rotational speed V11 of the motor 30 is detected.

Furthermore, when the rotation speed V11 of the motor 30 changes from high speed rotation to low speed rotation, the rotation speed V11 of the motor 30 changes from (e) to (g) in FIG.
As shown in FIG. 2, the time for the light to pass through the slit 42a becomes longer, and the output of the light receiving element 52b becomes larger than the determination level TH12 of the comparator 62. Therefore, the output of AND gate 65 is "H" and the output of AND gate 66 is "L".
, the input side of the light emitting element 51a and the power supply 70 are electrically connected, and the optical sensor 51 is switched.

In this way, the optical sensors 51 and 52 are automatically switched according to the rotational speed V11 of the motor 30, and the rotational speed 11V from low speed rotation to high speed rotation can be detected.

This rotation detection device has the following advantages.

(A) Two types of irradiation patterns 41 and 42 consisting of slits 41a and 42a having different incident areas are provided on the disk 40, and when rotating at low speed, the optical sensor 51 detects the slit 41a with a small incident area. At high speed rotation, the optical sensor 52 detects the slit 42a having a large incident area. Therefore, the amount of light received by the light receiving element 51b when the motor 30 rotates at low speed and the amount of light received by the light receiving element 52b when the motor 30 rotates at high speed are as follows.
They can be taken almost the same. For this reason, the light receiving element 51
b, and electrical signals S51 and S obtained by the light receiving element 52b.
52 are both output as stable waveforms. By processing the electrical signals S51 and S52 in the signal processing circuit 80, the rotational speed V11 can be reliably measured.

(B) The determination circuit 60a determines the measurement range of the rotational speed of the motor 30 based on the outputs of the light receiving element 51b and the light receiving element 52b, and outputs control signals Sa and Sb. Based on the control signals Sa and Sb, the switching circuit 60b switches the optical sensor 51 at an appropriate switching timing.
and the optical sensor 52. Therefore, a change to the irradiation pattern corresponding to the rotation range is automatically performed, and rotation speeds from low speed rotation to high speed rotation can be measured with one rotation detection device.

Second Embodiment FIG. 7 is a schematic diagram of a rotation detection device showing a second embodiment of the present invention. Note that common elements with those in FIG. 1 are given the same reference numerals.

The second embodiment differs from the first embodiment in that the rotation of the motor 30-1 is measured at both low-speed rotation and high-speed rotation, and the optical sensor 51-
1 and the optical sensor 52-1 is performed by a changeover switch 90 manually operated from the outside instead of the changeover means 60 of the first embodiment.

The changeover switch 90 is the input side switch 9
0a and the output side switch 90b are linked, and the input side switch 90a has contacts 91, 92, 93.
It consists of The input side of the light emitting element 51a-1 is connected to the contact 91, and the input side of the light emitting element 52a-1 is connected to the contact 91.
Connected to 2. Contact 93 is connected to drive power source 70 . The input side switch 90b has contacts 94 and 95.
, 96. The output sides of the light receiving element 51b-1 and the light receiving element 52b-1 are connected to contacts 94 and 95, respectively.
It is connected to the. Contact 96 is connected to signal processing circuit 80 . FIG. 8 is a waveform diagram of the electrical signals S51 and S52, in which (a) shows the waveform during low speed rotation, and (b) shows the waveform during high speed rotation.

When measuring the rotational speed of the motor 30-1 rotating at a low speed using this rotation detection device, the contact 93 of the input side switch 90a is connected to the contact 91 side, and the contact 96 of the output side switch 90b is connected to the contact 91 side. Connect to the contact 94 side. The drive power source 70 is connected to the light emitting element 51a-1, and the light from the light emitting element 51a-1 is transmitted to the disk 40 rotating at a low speed.
The irradiated pattern 41-1 above -1 is irradiated with light, and the light is inputted to the light receiving element 51b-1 through the slit 41a. The incident light is converted into an electric signal S51 by the light receiving element 51b-1, and sent to the signal processing circuit 80, where the rotation speed is output.

On the other hand, when measuring the rotational speed of the motor 30-1 at high speed, the selector switch 90 is switched. Contact 93 of input switch 90a is connected to contact 92, and contact 94 of output switch 90b is connected to contact 95. The driving power source 70 is connected to the light emitting element 52a-1, and the light from the light emitting element 52a-1 is input to the light receiving element 52b-1 through the slit 42a having a large incident area. Therefore, the amount of light received by the light receiving element 52b-1 can be made almost the same as the amount of light received by the light receiving element 51b-1 during low speed rotation.
The electric signals S51 and S52 obtained in 1 are shown in FIG. 8(a),
As shown in (b), both are output as stable waveforms.

The second embodiment has the same advantage (A) as the first embodiment, and also has the advantage that the rotation speed of the motor 30-1 can be measured at low speed rotation and at high speed rotation. This can be done with one rotation detection device.

Third Embodiment FIG. 9 is a perspective view of a main part of a rotation detection device showing a third embodiment of the present invention, FIG. 10 is a partially enlarged view of FIG. 9, and FIG. 11 is a partial enlarged view of FIG.
It is an enlarged view of the electrode part inside.

The third embodiment is different from the first and second embodiments in that the irradiated pattern 43 is formed by arranging liquid crystal elements 43a on the disk 40-2, and the irradiated pattern 43 is
The point is that a reflective optical sensor 53 is provided correspondingly. Note that common elements with those in FIG. 1 are given the same reference numerals.

A plurality of liquid crystal elements 43a are arranged on the circumference of the disk 40-2 to form an irradiated pattern 43. The liquid crystal element 43a is normally cloudy and scatters light, but when a voltage is applied between the electrodes, it becomes transparent and forms an opening 43-1. This liquid crystal element 43
a is connected to an annular negative electrode 44a and a positive electrode 44b, and a negative electrode 44a and a positive electrode 44c provided at the periphery of the shaft 40a via a wiring pattern.

Each electrode 44a, 44b, 44c is shown in FIG.
As shown in FIG.
0c is in contact. Electrodes 100a, 100b, 100
c is connected to an external power supply (not shown), and the electrode 100
A is connected to the negative terminal of the power supply, and electrodes 100b and 100c are connected to the positive terminal. Driving control of the liquid crystal element 43a is performed by turning on and off the power supply. By changing the voltage supplied to the liquid crystal element 43a,
For example, the size of the opening 43-1 of the liquid crystal element 43a can be changed in three measurement ranges: low speed rotation, medium speed rotation, and high speed rotation.

In this rotation detection device, in the case of low speed rotation,
Light from the light emitting element 53a passes through the opening 43-1,
The light is incident on the light receiving element 53b. The electrical signal S53 of the light receiving element 53b is output to the signal processing section 80. When the rotation of the motor changes and the rotational speed increases to near medium speed rotation, the amount of light received decreases and the output of the light receiving element 53b decreases. Therefore, the electrodes 100a and 100b are turned on, and a voltage is applied to the liquid crystal element 43a. Then, the liquid crystal element 43a
changes to be transparent, and the opening 43-1 (width a in the figure) is enlarged. At this medium speed rotation, the light from the light emitting element 53a is
The light enters the light receiving element 53b through the irradiated portion having a large transmission area, the amount of light received by the light receiving element 53b becomes constant, and an electric signal S53 is output to the signal processing section 80. Furthermore, when the rotation of the motor changes to high speed rotation and the rotation speed increases,
The output of the light receiving element 53b decreases. Therefore, the electrode 100
A and 100c are turned on, and a voltage is applied to the liquid crystal element 43a. Then, the opening 43- of the liquid crystal element 43a
1 is further enlarged (width b in the figure), and the amount of light received by the light receiving element 53b becomes constant. In addition, when the rotation speed changes from high speed rotation to medium speed rotation or low speed rotation, the opening 4
3-1 is reduced, and an electrical signal S53 with a stable waveform is output to the signal processing section 80.

The third embodiment has the following advantages.

(i) The irradiated portion is constituted by a liquid crystal element 43a, and the size of the opening 43-1 of the liquid crystal element 43a is changed by an external voltage. For this reason,
The incident area through which the light passes can be arbitrarily changed, and the amount of light received by the light receiving element 53b remains constant in accordance with the rotation speed. Thereby, the measurement range of the rotational speed of the motor can be widened, and any rotational speed in a wide range can be detected with one rotation detection device.

(ii) In FIG. 1, two types of irradiation patterns 41 and 42 are formed on the disk 40 in order to detect all rotation speeds from low speed rotation to high speed rotation.
A number of optical sensors 51 and 52 corresponding to the irradiated patterns 41 and 42 are provided. In this embodiment, since the irradiated portion is constituted by the liquid crystal element 43a, the transmission area can be changed, and the irradiated pattern 43 can be formed in one row. Also,
One optical sensor 53 may be used. This simplifies the structure and allows the rotation detection device to be miniaturized.

(iii) Since there is only one optical sensor 53, the circuit configuration is simplified and signal processing in the signal processing section 80 is facilitated.

(iv) The size of the transmission area of the irradiated portion is determined by applying a voltage to the liquid crystal element 43a. Therefore, the irradiation area can be changed even during rotation.

Fourth Embodiment FIG. 12 is a partial perspective view of a rotation detecting device showing a fourth embodiment of the present invention, and FIG. 13 is a partially enlarged view of FIG. 12. Note that common elements with those in FIG. 9 are given the same reference numerals.

In this embodiment, the electrodes 100a, 10 in FIG.
0b, 100c, the drive control of the liquid crystal element 43a-1 is performed by the solar cells 110a, 1, which are control signal receiving means.
10b.

A shaft 40a is mounted on the disk 40-3.
Annular solar cells 110a and 110b are mounted on the periphery of the solar cells 110a and 110b, and a light source 120
a, 120b are provided.

In this embodiment, the light source 120a or the light source 12
Based on the control signal caused by the lighting of 0b, the light sources 120a, 1
A voltage is generated in solar cells 110a and 110b by the light from 20b. This voltage is used to change the size of the opening 43-1 of the liquid crystal element 43a-1. Note that regarding detection of rotational speed, the same operation as in the third embodiment is performed.

This embodiment has the following advantages.

In FIG. 9, the control signal is sent and received by contacting the electrodes to control the driving of the liquid crystal element 43a, but in this embodiment, the control signal for driving the liquid crystal element 43a-1 is transmitted in a non-contact manner. Since the electrodes are exchanged, poor contact due to dirt or corrosion of the electrodes does not occur. Therefore, the slit pattern clearly appears, and the liquid crystal element 43a-1 operates reliably.
Rotation speed can be detected stably.

It should be noted that the present invention is not limited to the illustrated embodiment, but can be modified in various ways. Examples of such modifications include the following.

(1) FIG. 14 is a schematic perspective view showing a first modification of the irradiation pattern in FIG. 1. Figure 14
Here, irradiation patterns 44, 45, and 46 each consisting of irradiation areas having different irradiation areas are formed on three disks 40-4, 40-5, and 40-6. An optical sensor 54 is attached to each disk 40-3, 40-4, 40-5.
-1, 54-2, and 54-3 are provided. Even in this case, similarly to the first and second embodiments, the rotational speed can be measured over a wide range.

(2) FIG. 15(a) is a schematic perspective view showing a second modification of the irradiation pattern in FIG.
5(b) is a cross-sectional view.

In FIG. 15, the irradiated portions of the irradiated patterns 47 and 48 are constructed with reflective grooves 47a and 48a having different reflection areas in place of the slit 41a in FIG.
The reflected light of 48a is reflected by reflective optical sensors 55-1 and 55-2.
It detects this and outputs an electrical signal. Even in this case, similarly to the first and second embodiments, the rotational speed can be measured over a wide range.

(3) FIG. 16 is a schematic perspective view showing a third modification of the irradiation pattern in FIG. 1.

In FIG. 16, reflective grooves 49a and 49a-1 having different reflective areas are formed on the front and back surfaces of the disk 40-8. Reflective optical sensors 56-1, 56-2 are associated with the irradiated patterns 49, 49-1 to detect the presence or absence of the reflective grooves 49a, 49a-1. Even in this case, similarly to the first and second embodiments, the rotational speed can be measured over a wide range.

(4) The irradiated part is the slit 4 in FIG.
1a, 42a, and the reflective grooves 47a, 48 in FIGS. 15 and 16.
49a, 49a-1, for example, a radial pattern in which white and black are arranged alternately may be used to detect the irradiated pattern.

(5) In FIGS. 1 and 7, the rotational speed of the motor 30 is detected, but the configuration may be such that the electric signal output by the light receiving element is used for feedback control of a rotating body such as a motor. .

[0072]

[Effects of the Invention] As explained in detail above, according to the first invention, a plurality of types of irradiation patterns each consisting of irradiation areas having different irradiation areas are formed on a disk, and the irradiation pattern is adjusted according to the irradiation pattern. With multiple switchable optical sensors,
Even if the rotational speed measurement range changes, the amount of light received by the light receiving element remains constant, and a stable electrical signal can be obtained. This results in
Rotation speed can be detected over a wide measurement range.

According to the second invention, the optical sensor is switched by the switching circuit based on the control signal output from the determination circuit that determines the rotation range of the rotational speed of the rotating body, so that the optical sensor automatically The rotational speed can be accurately detected by irradiating an appropriate irradiation pattern.

According to the third aspect of the invention, since the irradiated portion is constituted by a slit or a reflective groove, the rotation detecting device can be constituted using an optical sensor similar to the conventional one.

According to the fourth aspect of the invention, since the irradiated portion is constructed of a liquid crystal element whose transmission area is variable, there is only one irradiated pattern, and therefore only one optical sensor is required, and the rotating body Rotation speed can be detected with a simple structure.

According to the fifth invention, since the control signal for driving the liquid crystal element of the fourth invention is exchanged without contact, the operation of the liquid crystal element is stabilized and the rotational speed can be detected reliably.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a rotation detection device showing a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a conventional rotation detection device.

FIG. 3 is an output waveform diagram of FIG. 2;

FIG. 4 is another output waveform diagram of FIG. 2;

FIG. 5 is a perspective view of the disk in FIG. 1;

6 is an output waveform diagram of the optical sensor in FIG. 1. FIG.

FIG. 7 is a schematic configuration diagram of a rotation detection device showing a second embodiment of the present invention.

FIG. 8 is a waveform diagram of an electric signal S.

FIG. 9 is a perspective view of a main part of a rotation detection device showing a third embodiment of the present invention.

FIG. 10 is a partially enlarged view of FIG. 9;

11 is an enlarged view of the electrode section in FIG. 9. FIG.

FIG. 12 is a partial perspective view of a rotation detection device showing a fourth embodiment of the present invention.

FIG. 13 is a partially enlarged view of FIG. 11;

FIG. 14 is a schematic perspective view showing a first modification of the irradiation pattern in FIG. 1;

15 is a schematic perspective view showing a second modification of the irradiation pattern in FIG. 1. FIG.

16 is a schematic perspective view showing a third modification of the irradiation pattern in FIG. 1. FIG.

[Explanation of symbols]

41a, 42a slit 41, 42 Irradiated pattern 30 Motor 40 Disc 51a, 52a Light emitting element 51b, 51b Photo receiving element 51, 52 Optical sensor 60 Switching means 60a Judgment circuit 60b switching circuit 43a Liquid crystal element 120a, 120b solar cell S51, S52 Electrical signal Sa, Sb control signal

Claims (5)

[Claims] 1. A disk having an irradiated pattern formed of a plurality of irradiated parts arranged on a circumference and rotated by a rotary body; a light emitting element that irradiates the irradiated parts with light using driving power; an optical sensor having a light receiving element that converts light from the irradiated part into an electrical signal, converting the output of the light receiving element into a pulse signal, and counting the number of pulse signals to determine the rotational speed of the rotating body. In the rotation detecting device, the irradiated area of the irradiated part is set to a size that allows the light receiving element to receive a predetermined amount of light in accordance with the measurement range of the rotational speed of the rotating body, and the irradiated area forming a plurality of types of irradiation patterns consisting of different irradiation areas on one or more disks rotated by the rotating body,
A rotation detection device further comprising a plurality of optical sensors that can be switched by a switching means in correspondence with the plurality of types of irradiation patterns. 2. The rotation detection device according to claim 1, wherein the switching means compares a determination level set according to the measurement range with an output level of the optical sensor to determine the rotation speed measurement range of the disk. and a switching circuit that switches either input or output of the optical sensor based on the control signal. Detection device. 3. The rotation detecting device according to claim 1, wherein the irradiated portion is composed of a slit or a reflective groove. 4. The rotation detection device according to claim 2, wherein the irradiated portion is constituted by a liquid crystal element whose transmission area of light from the light emitting element can be varied based on the control signal. Rotation detection device. 5. The rotation detecting device according to claim 4, wherein the control signal is generated externally by non-contact receiving means.