JP4716463B2 - Multi-turn absolute encoder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotary encoder used for high-accuracy position detection and the like, and more specifically, a multi-rotation type absolute encoder capable of discriminating an erroneous counting of rotational speed by detecting an error in position data for counting the rotational speed. For value encoders.
[0002]
[Prior art]
As a conventional rotary encoder, for example, the one shown in FIG. 10 is known. In the figure, basic components for counting the number of rotations of the rotary encoder are extracted and represented in a block diagram. Other functions necessary as an encoder are omitted here.
[0003]
In the figure, the rotary encoder shapes the waveform of the position data signal of the code plate detected by the detecting means 1 for detecting the position information of the code plate, the code plate 2 having the position information, and the detecting means. The waveform shaping means 3, the data processing means 4 for processing the position data signal obtained from the waveform shaping means 3 in synchronization with a predetermined clock, and the rise (HP) of the position data signal output from the data processing means 4 ), An edge detection means 5 for detecting a falling (LP) edge, and a rising signal (HP) and a falling signal (LP) output from the edge detection means to select a + count signal (UP), − By the selection means 6 for generating the count signal (DOWN) and the input of the + count signal (UP) and the -count signal (DOWN), the up-counting is performed. Or with a counting means 7 counts down, or apply detection timing to said detecting means, data processing means 4, the edge detecting means 5 a timing generator 8 supplies the clock for synchronization.
[0004]
Further, the code plate 2 has a structure as shown in FIG. 9, for example. That is, when viewed from the front, two discs having different diameters and 180 ° cutouts are combined so that the cutout positions are shifted by 90 °. A hatched portion in the figure corresponds to this notch, that is, a slit portion. By combining these two slits, an A region (θA °), a B region (θB °), and a C region (θC °), respectively. , And D region (θD °). The state of each slit is detected by photosensors SA and SB which are detection elements of the detection means 1.
[0005]
Next, the operation of the encoder having such a configuration will be described. When the code plate 2 rotates, a pulse signal, which is a position data signal corresponding to the slit of the code plate, is generated in each of the photosensors SA and SB by the detection speed. This pulse signal is shaped into substantially rectangular pulse waveforms DA1 and DB1 so that noise and the like are removed by the waveform shaping means 3 and can be input to the logic circuit.
[0006]
The shaped position data signals DA1 and DB1 are input to the data processing means 4 that operates in synchronization with the slit detection timing signal. The data processing means 4 samples the data signal by the clock CK1 synchronized with the operation of the detecting means 1 for detecting the slit of the code plate 2, and holds the input state of the data signals DA1 and DB1.
[0007]
One of the position data signals DA2 processed by the data processing means 4 is input to the edge detection means 5. The edge detection means 5 detects the rising (HP) and falling (LP) edges of the input signal and outputs signals HP and LP corresponding to the rising (HP) and falling (LP) edges. The output of the edge detection means 5 is input to the selection means 6. The other signal DB2 processed by the data processing unit 4 is input to the selection unit 6, and the rotation direction of the encoder is determined from the output of the edge detection unit 5, and according to the rotation direction CW / CCW. The UP output and DOWN output are output by 1 pulse per rotation.
[0008]
That is, since the code plate 2 has a 180 ° slit with a 90 ° phase shift, the phase of the position data signals DA1 and DB1 output differs depending on the rotation direction, and the rising (HP) and falling (LP) ) The front-rear relationship between the two signals can be grasped by the edge, and thereby the direction of rotation can be determined.
[0009]
In this way, according to the timing signal supplied from the timing generating means 8, the slit of the code plate 2 is detected at a predetermined period to be a position detection signal, and this is converted into a UP / DOWN signal from the phase relationship between the two signals. The number of rotation is counted by the counting means 7 after conversion.
[0010]
By the way, in such an encoder that counts the number of revolutions, it is necessary to back up the counting circuit with a battery and count the number of revolutions of the encoder even when the main power is turned off. However, if the counting circuit is operated in the same manner as when the main power supply is ON, the battery current consumption increases, and the battery life is reduced, which is not practical. For this reason, in the detection means 1 as described above, the light emission element LED for slit detection is pulse-lit by the timing generation means 8, and sampling is performed in synchronization with this to reduce the current consumption of the battery.
[0011]
However, in the method of detecting the rotation speed by such pulse lighting, the response speed when the main power supply is turned off is determined by the lighting cycle of the light emitting element LED. For this reason, if the lighting cycle is delayed to reduce the average current consumption in consideration of the battery life, the response rotation speed cannot be increased. Further, although the response rotational speed is set with a considerable margin, there is a problem that it is difficult to set the response rotational speed near the limit in consideration of the safety factor and the like.
[0012]
Furthermore, if the encoder rotates at a rotational speed that is higher than the response speed, an error may occur in the rotational speed count value. If the data is restarted as it is, the device that uses the encoder data may be damaged, or the basic function of the encoder may be impaired.
[0013]
[Problems to be solved by the invention]
An object of the present invention is to make it possible to discriminate a counting error in the rotational speed, set an allowable rotational speed close to the limit when the main power supply is turned off, and increase the response speed without increasing current consumption. A multi-turn absolute encoder is provided.
[0014]
[Means for Solving the Problems]
The above object is achieved by the following configuration.
(1) a code plate that provides at least three types of different position information, a detection unit that detects position information of the code plate, a timing generation unit that provides detection timing to the detection unit,
Counting means for counting by a signal obtained from the detection means;
From the position data of the code plate obtained from the detection means, with data error detection means for detecting an error in the position data,
There are at least two sets of counting means and data error detecting means,
Data correction means for correcting the count value of the corresponding count means to the count value of the count means in which no error was detected by the error signal of the position data detected by any of the data error detection means,
The data error detection means is a multi-rotation absolute value encoder that detects an error in position data as a detection error when a signal indicating the code plate position data obtained from the detection means changes in the same phase.
(2) By an error signal of position data detected by any one of the data error detection means,
The multi-rotation type absolute value encoder according to (1), further including data switching means for outputting a count value of the counting means in which no error is detected.
(3) The multi-rotation absolute value encoder according to (1) or (2), wherein the data correction unit performs correction by limiting a region of position information.
(4) The multi-rotation absolute value encoder according to any one of (1) to (3), wherein an error signal is output only when all of the data error detection means detect an error.
(5) The multi-rotation absolute value encoder according to any one of (1) to (3), wherein an error signal is output when any of the data error detection means detects an error.
[0015]
[Action]
In order to count the number of rotations by the counting means 7 (response rotational speed Nr), the areas A to D of the slits TA and TB correspond to the detection elements SA and SB with respect to the rotation of the code plate 2 as shown in FIG. When passing through the position, it is necessary that the light emitting element LED be lit once or more. That is, since each area A to D is determined by the combination of the presence or absence of the slits TA and TB, it is necessary to detect the slit in each area A to D. The rotation direction and the number of rotations can be measured by converting the signals SA and SB of the detection element corresponding to each detected slit into a phase difference 2 signal synchronized with a predetermined clock by the data processing means 4. .
[0016]
Here, the relationship between the detection of each region and the error will be verified. FIG. 7 is a timing chart showing the relationship between detection of each region and error.
[0017]
In the figure, no error occurs when consecutive areas (◎) DA, AB, BC, CD are detected. However, when the operation speed increases or the detection speed decreases, the next area (◯) AC, BD is detected by skipping one area, resulting in an error. Further, when the operation speed increases or the detection speed decreases, the next areas (●) DC, AD, BA, and CB are detected by skipping the two areas. However, since this is an adjacent region during reverse rotation, it cannot be determined whether or not there is an error, and the state is indefinite.
[0018]
FIG. 8 is a timing chart showing the operation of each part of such an encoder (example in FIG. 10). The slits TA and TB are changed corresponding to the areas A, B, C and D, respectively. The lighting signal LEDON of the light emitting element LED is output at a constant cycle, but it is necessary to light in any of the areas A to D of the slits TA and TB. A clock CK1 given to synchronize the data processing means is also output in synchronization with the LED lighting signal LEDON. The clock CK2 that synchronizes the edge detection means 5 is continuously output in a predetermined cycle in synchronization with the clock CK1. The signals DA1 and DB1 obtained by shaping the outputs of the detection elements SA and SB of the detection unit 1 by the waveform shaping unit by the rotation of the code plate 2 are converted into the slits of the code plate 2 by the data processing unit 4 in a normal state. The matched phase difference 2 signals DA2 and DB2 are obtained.
[0019]
Here, the response speed Nr (r / min) of the counting circuit that counts the number of rotations is obtained by the following equation.
Nr = 60 / Ts × Pr (Pr = 360 ° / θr)
Ts: Light emitting element LED lighting cycle (S)
θr: Minimum angle (°) of θA to θD
Pr: Number of divisions per rotation with respect to θr
Note) The TA and TB patterns and the LEDON signal are asynchronous signals.
[0020]
Then, as shown in the example, when the encoder rotates beyond the response speed Nr, when the areas A to D of the slits TA and TB pass through the detection elements SA and SB with respect to the rotation of the code plate 2, The lighting of the light emitting element LED is not in time and passes to the next area (areas A⇔C, B⇔D). In such a case, the respective areas of the slits TA and TB cannot be discriminated, and there is no phase difference at the change position of the two signals of 1 pulse / rotation of the output of the data processing means 4, and the counting means 7 has an error in counting. Occurs. As can be seen from the figure, the output signals DA2 and DB2 of the data processing means 4 are in phase. When the in-phase state of the two signals DA2 and DB2 is detected and held, an error signal ERR is obtained.
[0021]
Further, the response speed Nm (r / min) at which a counting error is detected in the circuit for counting the number of revolutions is given by the following equation.
Nm = 60 / Ts × Pm (Pm = 360 ° / θM)
Ts: lighting cycle of light emitting element LED
θM: Minimum angle (°) of θA + θB, θB + θC, θC + θD, θD + θA
Pm: Number of divisions per rotation for θM
[0022]
As described above, by detecting the simultaneous timing operation of the two signals output from the data processing means 4, it is possible to detect a detection error of the position data of the code plate 2, that is, a counting error. By providing two or more rotation measurement systems from the detection means-waveform shaping means to the count means, the count value on the error side can be corrected with the other normal count value. Therefore, even if the lighting cycle of the light emitting element LED is not increased, the allowable rotational speed can be set near the limit, and the allowable rotational speed can be increased.
[0023]
【Example】
Next, typical embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a basic configuration of a portion for measuring and counting the rotation of the encoder of the present invention. Other components are omitted here.
[0024]
In the figure, a rotary encoder according to the present invention includes a code plate 2 having predetermined code data, detection means 1 for detecting the code data of the code plate 2, waveform shaping means 3a, 3b, and data processing means 4a. 4b, edge detection means 5a, 5b, selection means 6a, 6b, and counting means 7a, 7b. The data error detection means 9a and 9b, the area confirmation means 11, the data correction means 12a and 12b, and the error output means 13 are further included, and the data processing means 4, the edge detection means 5, and the data error detection means. 9 has a timing generating means 8 for supplying a timing signal to 9.
[0025]
The waveform shaping means 3a, 3b, data processing means 4a, 4b, edge detection means 5a, 5b, selection means 6a, 6b, counting means 7a, 7b, and data error detection means 9a, 9b are at least two sets or more. It has (2 sets in the illustrated example).
[0026]
The detecting means 1 detects position information given by the slits of the code plate. As shown in the illustrated example, the detection means 1 is mainly composed of a light emitting element LED and light receiving elements SA, SB, SC, SD for detecting light from the light emitting element LED. The code plate 2 provides at least three types of position information. In this example, the position information is formed using slits. In the illustrated example, a transmissive slit is used, but a reflective slit may be used, and it may be replaced with a magnetic type.
[0027]
The waveform shaping means 3a and 3b convert the position data signal of the code plate 2 detected by the detection means, that is, the waveform of the output signal of the light receiving elements SA and SB into a signal waveform and signal level suitable for processing by a logic circuit. Shape it. The waveform shaping means 3a and 3b can be easily configured by known circuits and elements for shaping the waveform and adjusting the signal level.
[0028]
The data processing means 4a and 4b process the position data signal obtained from the waveform shaping means 3a and 3b in synchronization with a predetermined clock CK1 obtained from the timing generation means 8. That is, the position data signals DA1, DB1, DC1, and DD1 are output as pulses synchronized with the clock CK1. The data processing means 4a and 4b can be constituted by, for example, D-type flip-flops.
[0029]
The edge detection means 5a and 5b detect rising (HP) and falling (LP) edges of the position data signal which is the phase difference 2 signal output from the data processing means 4a and 4b. The edge detection means 5a and 5b output rising signals and falling signals. The selection means 6a and 6b select this and generate a + count signal and a -count signal. The selection means 6a and 6b can be configured by a combination of gate elements (circuits). The + count signal and -count signal are input to the counting means 7a and 7b. The counting means 7a and 7b perform up-counting or down-counting with a + count signal and a -count signal, and can be constituted by a known counter element or circuit, a combination of a gate element and a flip-flop, a processor, or the like. .
[0030]
The timing generation means 8 gives the detection means 1 a lighting signal LEDON of the light emitting element LED which is the detection timing, and is synchronized with the data processing means 4a, 4b, the edge detection means 5a, 5b, and the data error detection means 9a, 9b. Clocks CK1, CK2, and CK3 are supplied. This timing generation means 8 can be constituted by an oscillation circuit, a frequency divider, a processor, or the like.
[0031]
The data error detection means 9a and 9b monitor the phase relationship of the change positions of the two signals DA2 and DB2 which are the outputs of the data processing means 4, and detect when the two signals DA2 and DB2 change in the same phase. It is determined that there is an error, and an error signal ERR is output.
[0032]
A detailed configuration example of such data error detection means 9a, 9b is shown in FIG. The data processing means 4 in the figure is constituted by two D-type flip-flops FF41 and FF42 in this example, and operates to hold an input signal in synchronization with the clock CK1. The data error detection means 9 (9a, 9b) extracts and delays the two input signals DA2 and DB2 in synchronization with the clock CK3 by the two-stage flip-flops FF51, 53, FF52 and 54, and the flip-flops. The exclusive OR of the signals before and after the FFs 53 and 54 is obtained by the gates EXOR 51 and 52, and the rise and fall of the signal are extracted. Then, the logical product is obtained by the gate AND51, and only a change at the position of the same phase is taken as an error into the shift register constituted by the flip-flops FF55, FF56, FF57, and FF58, and the signals are sequentially delayed. Then, each output of these flip-flops FF55, FF56, FF57, and FF58 is taken out, and the logical product is obtained by AND52 and AND53, thereby outputting an error signal ER1 (ER2) or L01 (L02).
[0033]
Note that the clock signal CK is input to the clock CK terminals of the flip-flops FF55, FF56, FF57, and FF58, and operates as a shift register synchronized with the clock signal. An output signal having a desired pulse width is obtained by obtaining a logical product of the outputs delayed in synchronization with the clock signal CK. A timing chart of such a circuit is shown in FIG. As is apparent from FIG. 3, it can be seen that the output of the AND 51 is delayed in synchronization with the clock signal CK, and the error signal ER1 (ER2) or L01 (L02) having a predetermined signal width is output.
[0034]
In the present invention, two or more sets of the waveform shaping means 3a and 3b, the data processing means 4a and 4b, the edge detection means 5a and 5b, the selection means 6a and 6b, the count means 7a and 7b, and the data error detection means 9a and 9b. Therefore, when an error is detected by any one of the data error detection means 9a and 9b, the count value of the count means in which no error is detected is calculated as the count value of the count means in which the error is detected. It can be corrected to a numerical value. For this reason, reliability can be maintained even when the operation speed of the encoder is increased to a marginal speed at which counting errors occur, and the operation speed can be improved while maintaining low power consumption.
[0035]
The correction operation can be performed as follows.
The output Q2 of the register G2 is connected to the data input terminal D1 of the counting means 7a via a data bus. The data output Q2 of the counting means 7b is connected to the input D2 of the register G2. On the other hand, the output Q1 of the register G1 is connected to the data input terminal D2 of the counting means 7b via a data bus. The data output Q1 of the counting means 7a is connected to the input D1 of the register G1.
[0036]
The second error output L01 of the data error detecting means 9a is connected to the preset input L1 of the counting means 7a, and the second error output L02 of the data error detecting means 9b is connected to the preset input L2 of the counting means 7b. Is connected. Therefore, when the second error output L01, L02 of any one of the data error detection means 9a, 9b becomes active, the corresponding preset input of the counting means 7a, 7b becomes active, and the respective data input terminals D1, Data is read from D2 and preset. At this time, since the data outputs Q2 and Q1 of the other counting means 7b and 7a are inputted to the respective data input terminals D1 and D2, as a result, the count values of the other counting means 7b and 7a are corrected. It will be.
[0037]
The first error outputs ER1 and ER2 of the data error detection means 9a and 9b are connected to the input terminals I1 and I2 of the error output means 13, respectively. As will be described later, the error output means 13 gives priority to correction or gives priority to error output depending on whether the output O is the logical product AND or logical OR of the inputs I1 and I2. Can be selected.
[0038]
Even when the output O of the error output means 13 is output under the logical AND condition to give priority to correction, a signal of the logical OR condition may also be output as a warning signal in which an error has occurred.
[0039]
Next, the timing at which a counting error occurs and the operation of the encoder will be described.
[0040]
As described above, when two or more sets of rotation measuring means are used, the operation of three signals and four signals can be considered.
[0041]
First, the operation of three signals will be considered. FIG. 4 is a timing chart showing the relationship between three signals (position signal = slit) for rotation measurement, detection of each region, and error.
[0042]
In the figure, since position detection is performed using three signals, there are three types of slit position information to be used: TA, TB, TC = TA, and TD. Therefore, the areas defined by the slits are the first set of A1, B1, C1, and D1 and the second set of A2, B2, C2, and D2, as shown in the illustrated example. Is not constant.
[0043]
Consider the relationship between area detection and error at each speed.
(1) When detecting continuous areas (◎)
When D1-A1 and D2-A2, A1-A1 and A2-B2 are detected, no error occurs.
[0044]
(2) When detecting the next area (○) by skipping one area
Like D1-A1 and D2-B2, errors and non-detections are mixed. For this reason, the operation at this speed can be compensated by correcting (rewriting) the count value of the counting means of the group where the error is detected to the count value of the group where the error is not detected.
Here, the response speed Nr3 (r / min) at which rotation can be measured by performing data correction is obtained by the following equation.
Nr3 = 60 / Ts3 × Pr3 (Pr3 = 360 ° / θr3)
Ts3: Light emitting element LED lighting cycle (S)
θr3: Minimum angle (°) of θA1, θB2, θC1, θD2, θB1 + θC2, and θD1 + θB2
[0045]
In addition, compared with conventional encoders (calculated with ideal values)
θr / θr3 = 90 ° / 120 ° = 0.75
It can be seen that the response speed is improved by about 25%.
[0046]
(3) When detecting the next area (●) by skipping two areas
Like D1-B1 and D2-B2, errors are detected in all areas. For this reason, a counting error occurs in all the counting means.
Here, the response speed Nm3 (r / min) at which a counting error occurs is obtained by the following equation.
Nm3 = 60 / Ts3 × Pm3 (Pm3 = 360 ° / θm3)
Ts3: Light emitting element LED lighting cycle (S)
θm3: θA1 + θB1, θB1 + θC1, θC1 + θD1, θD1 + θA1 minimum angle (°),
θA2 + θB2, θB2 + θC2, θC2 + θD2, θD2 + θA2 minimum angle (°)
[0047]
In addition, compared with conventional encoders (calculated with ideal values)
θm / θm3 = 180 ° / 180 ° = 1
It turns out that it is not different from the conventional one.
[0048]
(4) When the next area (□) is detected by skipping three areas
Since error detection and an indeterminate state that becomes an adjacent area at the time of reverse rotation coexist, both the counting means for counting the rotation and the data error detecting means cannot respond. Therefore, the operation in this state cannot be guaranteed.
[0049]
Next, the operation of four signals will be considered. FIG. 5 is a timing chart showing the relationship between four signals (position signal = slit) for rotation measurement, detection of each region, and error.
[0050]
In the figure, since position detection is performed using four signals, there are four types of slit position information to be used: TA, TB, TC, and TD. Therefore, the areas defined by the slits are the first set of A1, B1, C1, and D1 and the second set of A2, B2, C2, and D2, as shown in the illustrated example. Is constant, but there is a shift in the region of one rotation between the first set and the second set.
[0051]
Here, the counting means is prioritized and error output is only performed when an error occurs in all groups. In other cases, correction is performed, and the data error detecting means is prioritized, and errors occur in either group. When this occurs, the operation differs depending on whether an error is output. Therefore, the cases will be described separately below.
[0052]
[Counter priority]
(1) When detecting continuous areas (◎)
When D1-A1 and D2-A2, A1-B1 and D2-A2 are detected, no error occurs.
[0053]
(2) When detecting the next area (○) by skipping any one area
Like D1-B1 and D2-A2, errors and non-detections are mixed. For this reason, the operation at this speed can be compensated by correcting (rewriting) the count value of the counting means of the group where the error is detected to the count value of the group where the error is not detected.
Here, the response speed Nr41 (r / min) at which rotation can be measured by performing data correction is obtained by the following equation.
Nr41 = 60 / Ts4 × Pr41 (Pr41 = 360 ° / θr41)
Ts4: Light emitting element LED lighting cycle (S)
θr 41: θA1 + θA2, θA2 + θB1, θB1 + θB2, θB2 + θC1,
θC1 + θC2, θC2 + θD1, θD1 + θD2, θD2 + θA1 minimum angle (°)
(However, the signal overlap area is excluded)
[0054]
In addition, compared with conventional encoders (calculated with ideal values)
θr / θr41 = 90 ° / 135 ° = 0.67
It can be seen that the response speed is improved by about 33%.
[0055]
(3) When detecting the next area (●) by skipping one area
Like D1-B1 and D2-B2, errors are detected in all areas. For this reason, a counting error occurs in all the counting means.
Here, the response speed Nm41 (r / min) at which a counting error occurs is obtained by the following equation.
Nm41 = 60 / Ts4 × Pm41 (Pm41 = 360 ° / θm41)
Ts4: Light emitting element LED lighting cycle (S)
θm41: θA1 + θB1, θB1 + θC1, θC1 + θD1, θD1 + θA1 minimum angle (°),
θA2 + θB2, θB2 + θC2, θC2 + θD2, θD2 + θA2 minimum angle (°)
[0056]
In addition, compared with conventional encoders (calculated with ideal values)
θm / θm41 = 180 ° / 180 ° = 1
It turns out that it is not different from the conventional one.
[0057]
(4) When the next area (□) is detected by skipping any two areas
Since error detection and an indeterminate state that becomes an adjacent area at the time of reverse rotation coexist, both the counting means for counting the rotation and the data error detecting means cannot respond. Therefore, the operation in this state cannot be guaranteed.
[0058]
(5) When the next area (◇) is detected by skipping two areas
When the reverse rotation is performed in all the regions, an indefinite state that becomes an adjacent region is entered, so that both the counting means for counting the rotation and the data error detecting means cannot respond. Therefore, the operation in this state cannot be guaranteed.
[0059]
[Data error detection means priority]
(1) When detecting continuous areas (◎)
When D1-A1 and D2-A2, A1-B1 and D2-A2 are detected, no error occurs.
[0060]
Here, the response speed Nr42 (r / min) at which rotation can be measured is obtained by the following equation.
Nr42 = 60 / Ts4 × Pr42 (Pr42 = 360 ° / θr42)
Ts4: Light emitting element LED lighting cycle (S)
θr 42: θA1, θB1, θC1, θD1, θA2, θB2, θC2, and θD2 minimum angles (°)
[0061]
In addition, compared with conventional encoders (calculated with ideal values)
θr / θr42 = 90 ° / 90 ° = 1
It turns out that it is not different from the conventional one.
[0062]
(2) When detecting the next area (○) by skipping any one area
Like D1-B1 and D2-A2, errors and non-detections are mixed. For this reason, an error signal on the side where an error is detected is output and a counting error is determined.
[0063]
(3) When detecting the next area (●) by skipping one area
Like D1-B1 and D2-B2, errors are detected in all areas. For this reason, an error signal is output to make a counting error.
[0064]
(4) When the next area (□) is detected by skipping any two areas
Since there is a mixture of error detection and an indefinite state that becomes an adjacent area during reverse rotation, a counting error is assumed.
[0065]
Here, the response speed Nm42 (r / min) at which a counting error occurs is obtained by the following equation.
Nm42 = 60 / Ts4 × Pm42 (Pm42 = 360 ° / θm42)
Ts4: Light emitting element LED lighting cycle (S)
θm42: θA1 + θB1 + θB2, θB1 + θC1 + θC2, θC1 + θD1 + θD2, θD1 + θA1 + θA2, θA2 + θB2 + θC1, θB2 + θC2 + θD1, θC2 + θD2 + θA2 + θ1 + θA2 + θ
(However, the signal overlap area is excluded)
[0066]
In addition, compared with conventional encoders (calculated with ideal values)
θm / θm42 = 180 ° / 270 ° = 0.67
It can be seen that the improvement is about 33%.
[0067]
(5) When the next area (◇) is detected by skipping two areas
When the reverse rotation is performed in all the regions, an indefinite state that becomes an adjacent region is entered, so that both the counting means for counting the rotation and the data error detecting means cannot respond. Therefore, the operation in this state cannot be guaranteed.
[0068]
As shown in FIGS. 4 and 5, there are counting points (one place x or two places x, y) for performing +1 (increment) and -1 (decrement) in the area of one rotation. In particular, when four signals are used, there is a difference between one counting point x and the other counting point y. For this reason, when correction is performed in the region between the counting points x and y (the overlapping region of A1 and D2), this region is detected by the region confirmation unit 11 and output from the region confirmation unit 11 as shown in FIG. It is necessary to connect O to the increment terminal +1 or decrement terminal -1 of each register 12a, 12b, and to increment or decrement the contents of each register 12a, 12b.
[0069]
Further, if correction is performed in the vicinity of the counting point, there may be a deviation in the correction value due to the data correction timing and the movement of the encoder shaft position from the detection of the data error. For example, if a data error is detected in the area D1 in FIG. 4 and the data is corrected before the encoder axis is moved to the area A1, the correction data is shifted by -1. For this reason, in the vicinity of the counting points x and y (in the case of FIG. 4, the region of D1 and A1, in the case of FIG. 5, the region of D1 and A1, D2 and A2, or an extra amount in which the correction value does not shift in consideration of the timing) It is better to correct the data by avoiding the area.
[0070]
Further, as shown in FIG. 6, data switching means 14 may be provided. Outputs Q1 and Q2 of the respective counting means 7a and 7b are inputted to the data inputs DA and DB of the data switching means 14 through the data bus. The first error signals ER1 and ER2 from the data error detection means 9a and 9b are input. The error signals ER1 and ER2 prohibit the output of data from the counting means 7a and 7b on the side where the error has occurred and output the data from the other counting means 7a and 7b. Note that the normal output side may be determined at the time of initial setting or the like according to the priority order. This data switching means can be configured by combining or combining ordinary switching elements, gate elements, data selectors, and the like.
[0071]
Thus, when two signals change at the same phase position among the three signals, four signals DA2, DB2, DC2, and DD2 obtained from the slit, it is determined that the detection error is caused by the slit, and the error signal is determined. Data error detection means for sending out is provided, and the count value of one set is corrected with the count value of the other set by this error signal, so even when the main power of the encoder is OFF, it is possible to determine the detection error of the rotational speed The allowable rotational speed can be set close to the limit, and the speed can be increased without increasing the current consumption. In addition, even if an error occurs, the status can be grasped. Therefore, if a rotation speed measurement error occurs, initialization can be performed again, such as finding the origin, and there is no risk of a serious failure occurring. .
[0072]
In this embodiment, the optical position detection means is described. However, the present invention is not limited to this, and the present invention can be applied to a magnetic detection method and a detection method using a mechanical contact. is there.
[0073]
【The invention's effect】
As described above, according to the present invention, it is possible to determine a miscount of the rotation speed, and set the allowable rotation speed near the limit when the main power supply is turned off, and can increase the speed without increasing the current consumption. A multi-turn absolute encoder can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a basic configuration of a portion for counting the number of rotations of an encoder according to the present invention.
FIG. 2 is a diagram showing a detailed configuration of a data error detection unit.
3 is a timing chart showing the operation of the circuit shown in FIGS. 1 and 2. FIG.
FIG. 4 is a timing chart showing a relationship between a slit area and an error in three signals.
FIG. 5 is a timing chart showing the relationship between slit areas and errors in four signals.
FIG. 6 is a block diagram showing a basic configuration of an encoder having data switching means.
FIG. 7 is a timing chart showing a relationship between a slit area of a conventional encoder and an error.
8 is a timing chart showing the operation of each unit in FIG. 9;
FIG. 9 is a front view showing an external configuration of a code plate.
FIG. 10 is a block diagram showing a basic configuration of a part for counting the number of rotations of a conventional encoder.
[Explanation of symbols]
1 detection means
2 Code plate
3a, 3b Waveform shaping means
4a, 4b Data processing means
5a, 5b Edge detection means
6a, 6b selection means
7a, 7b Counting means
8 Timing generation means
9a, 9b Data error detection means
11 Area confirmation means
12a, 12b registers
LED light emitting element
SA, SB, SC, SD detector

Claims (5)

A code plate that provides at least three types of different position information; a detection means that detects position information of the code plate; a timing generation means that provides detection timing to the detection means;
Counting means for counting by a signal obtained from the detection means;
From the position data of the code plate obtained from the detection means, with data error detection means for detecting an error in the position data,
There are at least two sets of counting means and data error detecting means,
Data correction means for correcting the count value of the corresponding count means to the count value of the count means in which no error was detected by the error signal of the position data detected by any of the data error detection means,
The data error detection means is a multi-rotation absolute value encoder that detects an error in position data as a detection error when a signal indicating the position data of the code plate obtained from the detection means changes in the same phase. By the error signal of the position data detected by any one of the data error detection means,
2. The multi-turn absolute encoder according to claim 1, further comprising a data switching means for outputting a count value of the counting means in which no error has been detected.   The multi-rotation type absolute value encoder according to claim 1 or 2, wherein the data correction means performs correction by limiting a region of position information.   The multi-rotation absolute value encoder according to any one of claims 1 to 3, wherein an error signal is output only when all of the data error detection means detect an error.   The multi-rotation absolute value encoder according to any one of claims 1 to 3, wherein an error signal is output when any of the data error detection means detects an error.

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