JPH04335113A - Encoder - Google Patents

Abstract

PURPOSE:To simplify the entire apparatus and to make it possible to perform detection in high resolution by outputting an incremental signal in response to the rotation of a rotary body, and outputting an analog signal corresponding to the rotary angle of the rotary body. CONSTITUTION:When a shaft 3 is rotated by one rotation, as many rectangular waves are outputted as the number (n) of slits 9. An incremental signal in a phase A is outputted from a main body 1 of an encoder. The voltage across a resistor element 11 is divided by the rotated angle of the shaft 3 based on the resistance value of the resistor element 11. Thus, an analog signal in a phase S is outputted. An A/D converter 14 converts the signal in the phase S into the 2-bit digital signal. A reference-clock generating circuit 15 generates a reference clock based on the signal in the phase A. Pulse generating circuits 16 and 17 generate clocks 1 and 2 whose HIGH levels are different from the reference clock from the circuit 15. The absolute-value information of the rotary angle stored in a ROM 18 is read out based on the incremental signal in the phase A with the converted digital signal in the phase S as an address.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an encoder that measures the rotational state of an object to be measured, such as the rotational angle and rotational speed. This relates to an absolute type encoder.

0002

2. Description of the Related Art Conventionally, photoelectric encoders have been widely used as measuring devices for detecting the rotation, movement, position, etc. of an object to be measured, and for detecting the rotation amount, rotation speed, etc. of a rotating mechanism.

FIG. 10 is a schematic diagram showing an example of a conventional so-called absolute type encoder (rotary encoder) for measuring the absolute amount of the displacement state (rotational state) of an object to be measured.

In the figure, 32 is a rotating disk that rotates around the rotating shaft 31, and an arbitrary (
A plurality of concentric tracks 32a are provided to generate binarized data elements according to angular positions (quantized). Each track 32a is optically provided with two
A plurality of slits 32b are provided with a pattern of digitized data, for example, transparent areas and non-transparent areas.

Reference numeral 34 denotes a fixed slit array, which has a plurality of openings 34a for selectively passing light beams from slits 32b provided on each track 32a. 33 is a light projecting means having a plurality of light projecting elements (LEDs), and 35 is a light receiving means having a plurality of light receiving elements.
D) 33 and each light receiving element 35 are connected to the fixed slit row 34 respectively.
are arranged so as to correspond to each opening 34a, respectively.

In the configuration shown in the figure, the light flux emitted from each light projecting element of the light projecting means 33 enters the light receiving means 35 after passing through the slit 32b and the fixed slit 34. At this time, the absolute rotational position of the rotating disk 32 is determined from the combination of output signals from each light receiving element.

[0007]

[Problems to be Solved by the Invention] In an encoder as shown in FIG. 10, in order to achieve high resolution, it is necessary to
It is necessary to increase the arrangement density of the patterns of the plurality of tracks 32a in order to detect minute areas of the patterns with high precision. For this purpose, it is necessary to use a fixed slit plate with a narrow slit width to limit the irradiation area and irradiate it with a sufficient amount of parallel light beam.

However, when trying to satisfy these conditions, there is a problem in that the entire device becomes complicated and large.

The present invention provides rectangular wave signal output means for outputting a rectangular wave signal and analog signal output means for outputting at least one analog signal by a rotating disc connected to a rotating shaft or a predetermined rotation of the rotating shaft. The purpose of the present invention is to provide an absolute encoder that is capable of high-resolution detection while simplifying the entire device by configuring elements appropriately.

0010

[Means for Solving the Problems] The encoder of the present invention has the following features:
means for outputting an incremental signal according to the rotation of a rotating object; means for outputting an analog signal according to the rotation angle of the rotating object; means for converting the analog signal into a 2-bit or more digital signal; and a rotation angle. and a memory in which absolute value information of is stored, and the content of the memory is read based on the incremental signal using the converted digital signal as an address.

[0011]

[Example] Figure 1 is a schematic diagram of the main parts of Example 1 of the present invention, Figure 2
2 is an enlarged perspective view of a portion of FIG. 1. FIG. In the figure, 1 is an encoder main body, and 2 is a signal processing section, which processes signals from the encoder main body 1.

In this embodiment, the signal processing section 2 forms an absolute signal from the incremental signal output from the encoder main body 1 and the analog signal of one revolution of the rotating disk 5 (rotating disk) 5. Next, each element will be explained.

3 is a shaft, 4 is a bearing, and 5 is a rotating disk.
A slit 6 is carved into the book. 7 is a light emitting part, for example L
It consists of ED. 8 is a light receiving element, and 9 is a fixed slit, which has the same pitch as the slit 6. The slit 6 and the fixed slit 9 are arranged on the optical axis of the LED 7 and the light receiving element 8. 10 is an electrode mount, one end of which is fixed to the shaft 3.

Reference numeral 11 denotes a resistance element, which has an annular shape and has a cutout in a portion thereof, and electrodes are attached to both ends of the cutout. The resistance value of the resistance element 11 is uniformly distributed over the circumference.

As shown in FIG. 2, the end surface of the electrode mount 10 and the resistance element 11 are in contact with each other, and as the shaft 3 rotates, the contact surface of the electrode mount 10 is brought into contact with the resistance element 11.
Touch and move on top. Reference numeral 12 denotes a band-shaped electrode, which is placed on the circumference of the shaft 3, the electrode mount 10, and the electrode mount 1.
0 and the resistive element 11 on the contact surface thereof. 13 is a brush, which is always in contact with the electrode 12.

Next, in the above configuration, when the shaft 3 is rotated from the outside, the rotating disk 5 and the electrode mount 10 rotate accordingly. At that time, the LED 7 and the light receiving element 8
When the slit 6 of the rotating disk 5 and the fixed slit 9 are aligned on the optical axis configured by The light does not enter the light receiving element 8. Therefore, the encoder main body 1 outputs rectangular waves corresponding to the number n of slits 9 when the shaft 3 makes one rotation. The signal at this time is an incremental signal, and this signal is now assumed to be the A phase. Further, a voltage Vi is applied between both ends of the resistive element 11.
n is applied, and the electrode mount 10 is connected to the resistive element 11.
By sliding on the top, the voltage is divided by the rotation angle θ of the shaft 3 depending on the resistance value of the resistance element 11, and that voltage appears on the electrode 12 and the brush 13.

Now, since the resistance value of the resistance element 11 is uniformly distributed over the circumference, the voltage Vout appearing on the brush 13 is expressed as Vout=θ/2π×Vin. The signal at this time is an analog signal,
Now let this signal be the S phase.

FIG. 3 is an explanatory diagram of the A phase of the n rectangular wave incremental signals and the S phase of the analog signal of one revolution of the rotary disk 5. Next, the signal processing section 2 will be explained.

14 is an A/D converter, which converts the S phase into 2
It is converted into a digital amount of m bits. A reference clock generation circuit 15 generates a reference clock from the A phase. 16 and 17 are pulse generating circuits, respectively, which generate clock 1 and clock 2 having different HIGH levels from the reference clock outputted from the reference clock generating circuit 15. 18 is a ROM, which is a nonvolatile read-only memory whose address is the digital quantity output from the A/D converter 14 and whose read permission signal is the clock 1 output from the pulse generation circuit 16; is written. A latch circuit 19 holds data output from the ROM 18.

In the above configuration, the reference clock generation circuit 15 generates a reference clock for the A phase of the incremental signal output from the encoder body 1 described above. FIG. 4 shows a timing chart of this embodiment. As shown in Figure 4, the reference clock is generated at the rising edge of phase A,
The period is determined by the rotation speed of the shaft 3. Here, the period at the maximum rotation speed is assumed to be T. The reference clock then becomes the sample-and-hold timing signal of the A/D converter 14 and the input signal of the two pulse generation circuits 16 and 17, and the clock 1 generated by the pulse generation circuit 16 becomes the reference clock.
rises at the same time as the reference clock rises, and becomes HI
The GH level time is T1.

On the other hand, the clock 2 generated by the pulse generating circuit 17 also rises at the same time as the reference clock rises, but the HIGH level time is T2. The relationship between T, T1, and T2 is T1 < T2 < T.

The S phase generated from the encoder body 1 is A/
The data is converted into a 2m bit digital signal by the D converter 14, and the data is determined after the HIGH level of the reference clock as shown in FIG. Thereafter, the 2m-bit digital signal becomes the address signal of the ROM 18, and the aforementioned clock 1 becomes the OE signal, and immediately after the fall of the clock 1, the data written at the 2m-bit address is outputted to the ROM 18. Furthermore, the data output from the ROM 18 at the falling edge of clock 2 is held and finally determined.

FIG. 5 shows the relationship between the address of the ROM 18 and the S phase. Here, since the rotation angle θ of the shaft 3 corresponds one-to-one to the S-phase voltage, the ROM
Address No. 18 corresponds to the S-phase voltage, and the rotation angle θ of the shaft 3 corresponding to that voltage is data in the ROM 18 written at the address at that time.

In this embodiment, the absolute amount of the rotation angle of the shaft 3 (rotary disk 5) is detected using the above-described configuration. 6 is a schematic diagram of a main part of a second embodiment of the present invention, and FIG. 7 is an enlarged perspective view of a portion of FIG. 6. Like the first embodiment, this embodiment also includes an encoder main body 1-2 and a signal processing section 2-2.

In the figure, shaft 3-2 and bearing 4-2
, rotating disk 5-2, slit 6-2, LED 7-2
, the light receiving element 8-2, the fixed slit 9-2, and other elements are the same as in the first embodiment.

Reference numeral 20 denotes a magnet, and different poles are arranged symmetrically with respect to the rotation center of the shaft 3-2. 21A, 2
1B and 21C are magnetoresistive elements, respectively, and the magnet 20
is measuring the magnetic field of Magnetoresistive elements 21A, 21B, 2
1C are arranged at intervals of 120 degrees on the circumference around the shaft 3-2.

In the above configuration, by rotating the shaft 3-2, the magnetic disk 5-2 is rotated as in the first embodiment.
A-phase of n rectangular wave signals is output per one rotation. Furthermore, since the magnet 20 also rotates by rotating the shaft 3-2, the magnetoresistive element 21A arranged around it,
U-phase, V-phase, and W-phase of a sine wave signal having one period per one rotation of the shaft 3-2 are output from 21B and 21C. Here, the phase difference between these three phases, U phase, V phase, and W phase is 12
It is 0 degrees. FIG. 8 shows the U phase, V phase, and W phase.

Next, the signal processing section 2-2 will be explained. As in the first embodiment, 14-2 is an A/D converter, 15-2 is a reference clock generation circuit, and 16-2 and 17-2 are pulse generation circuits. is being generated. 18-2 is ROM,
A latch circuit 19-2 holds data. Reference numeral 22 denotes an analog switch, which selects the U phase, V phase, and W phase using timing signals Y1, Y2, and Y3. A comparator 23 compares the U phase, V phase, and W phase at zero level and converts it into a TTL level rectangular wave.

24 is a lodge circuit, and comparator 2
From the output from 3, the upper 2 bits of address Am, Am-1 of ROM18-2 and timing signals Y1, Y2, Y
It is generating 3. FIG. 8 shows a timing chart of the signal processing circuit 2-2.

In the above configuration, the encoder body 1-2
The U-phase, V-phase, and W-phase outputted from the ROM 18-2 are converted by the comparator 23 into TTL level rectangular waves u, v, and w, and based on this signal, the logic circuit 24 outputs the signals from the ROM 18-2.
Address signals Am, Am-1 of the upper two bits of and timing signals Y1, Y2, Y3 are generated. As shown in FIG. 9, the timing of the signal Am rises at the falling edge of the rectangular wave u, and falls at the falling edge of the rectangular wave v.

The signal Am-1 rises at the fall of the rectangular wave w, and falls at the fall of the rectangular wave u. Also, timing signal Y1 is LO for both signals Am and Am-1.
HIGH level when W level, timing signal Y2
is a HIGH level when the signal Am is a LOW level and the signal Am-1 is a HIGH level, and the timing signal Y3 is a HIGH level when the signal Am is a HIGH level and the signal Am-1 is a LOW level.

Further, the analog switch 22 has U phase, V phase,
Select one of the W phases and set the timing signal Y1 to HIGH.
When the timing signal Y2 is at the HIGH level, the V phase is selected. When the timing signal Y3 is at the HIGH level, the W phase is selected. The signal selected here is set as the S phase, and this S phase becomes the input of the A/D converter 14-2, and is converted into a digital quantity and stored in the ROM 18-2 as A0 to Am.
-2 address signal.

After that, as in the first embodiment, the clock 1 generated from the A phase becomes the read permission signal, the clock 2 becomes the data holding signal, and when the shaft 3-2 rotates, the U phase,
The data written to the address of the ROM 18-2 determined by the V phase and W phase is output at the same timing as the A phase of the incremental signal. Figure 9 shows the S phase and ROM18-
2 shows the relationship between addresses and data.

In this embodiment, the absolute amount of the rotation angle of the shaft 3-2 (rotary disk 5-2) is determined in the same manner as in the first embodiment using the above-described configuration.

[0035]

According to the present invention, there is provided a rectangular wave signal output means for outputting rectangular wave signals of at least one bit, the number of which is proportional to the rotation angle of the rotary shaft, and at least one period or less per rotation of the rotary shaft. An analog signal output means for outputting one analog signal, a conversion means for converting the analog signal into a 2-bit or more digital signal, and a memory that uses the digital signal as an address and uses the 1-bit rectangular wave signal as a read permission signal. By providing this, it is possible to achieve an encoder capable of high-resolution detection while simplifying the entire device.

[Brief explanation of drawings]

[Figure 1] Schematic diagram of main parts of Example 1 of the present invention

[Figure 2]
Enlarged perspective view of a portion of Figure 1

[Fig. 3] An explanatory diagram showing the relationship between the incremental signal and the analog signal per rotation in the present invention

[Figure 4] Timing chart diagram of the signal processing section in Figure 1

[Figure 5] Explanatory diagram showing the relationship between the address, data, and S phase of the ROM in Figure 1

[Fig. 6] Schematic diagram of main parts of Example 2 of the present invention

[Figure 7]
Enlarged perspective view of a portion of FIG. 6

[Figure 8] Timing chart diagram of the signal processing section in Figure 6

[Figure 9] ROM in Figure 6
An explanatory diagram showing the relationship between address, data, and S phase.

[Figure 10] Schematic diagram of the main parts of a conventional absolute encoder

[Explanation of symbols]

1 Encoder body 2 Signal processing section 3 Shaft 4 Bearing 5 Rotating disk 6 Slit 7 Light emitting part 8 Photo receiving element 9 Fixed slit 10 Electrode mount 11 Resistance element 12 Electrode 13 Brush 14 A/D converter 15 Reference clock generation circuit 16, 17 Pulse generation circuit 18 ROM 19 Latch circuit 20 Magnet 21 Magnetoresistive element 22 Analog switch 23 Comparator 24 Lodge circuit

Claims (1)

[Claims] 1. Means for outputting an incremental signal in accordance with the rotation of a rotating object, means for outputting an analog signal in accordance with the rotation angle of the rotating object, and converting the analog signal into a 2-bit or more digital signal. and a memory in which absolute value information of a rotation angle is stored, and the content of the memory is read out based on the incremental signal using the converted digital signal as an address.