JPH032671A - displacement controller - Google Patents

Abstract

PURPOSE:To achieve a suppression of disability of a servo by shifting a displacement into a normal servo range forcibly when it is detected to be outside a servo range. CONSTITUTION:When a shift occurs in a positive way exceeding a normal servo range during a normal servo control, an output of a COMP 18 changes to 'H' from 'L' to be inputted into an S terminal of an FF21. An Q output of the FF21 moves to 'H' and an analog switch 12 is turned ON while an analog SW 10 is turned OFF. With the analog SW 12 ON, a power source voltage VCC is applied to a coil 7 to generate a force negative. A slit moves and a displacement output VA-B rises from 0 level and after the passage of an area of a fixed value, it begins to fall to enter a normal servo area. As the output VA-B passes near the 0 level, a zero crossing detector (ZCD) 20 is operated to transmit a pulse output to the FF21 through an OR gate 60 so that the Q output is turned to 'L'. This enables applying of a normal servo.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a displacement controller used in a device that measures a physical quantity by detecting displacement and applying a servo so that the displacement returns to a reference position.

(Background of the Invention) Conventionally, a servo accelerometer has been known as a typical device that detects displacement and applies displacement servo. A servo accelerometer is configured to detect rotational displacement of a pendulum that is proportional to acceleration, amplify the detected current, flow it through a coil to return the pendulum to its original position, and calculate acceleration from the current flowing through the coil. ing. The circuit configuration at this time is the 10th
It is as shown in the figure (details will be described later).

The mechanical configuration and positional relationship of the optical system of this type of conventional servo accelerometer are as shown in FIGS. 11 and 12.
The displacement of the pendulum 51 is set to "0" by detecting the displacement of the pendulum 51 using the circuit shown in FIG.
” The servo is applied to detect the acceleration. In this configuration, the slit 50 as well as the pendulum 51
As shown in the figure, when the displacement X moves, for example, in the direction of the arrow, the displacement output VA-11 (see FIG. 10) operates as shown in FIG. 13.

In Fig. 13, photodiode 3 is located between X j and X 1.
The area between X Z X a is the light receiving area of the photodiode 4 . Displacement X is greater than or equal to X1
When it is less than 2, no light reaches either photodiode, and normal servo operation can no longer be performed. In order to avoid this, conventionally, the range in which the pendulum 51 (and the slit 50) can be rotated is limited by using stoppers 52 and 53, and the displacement X can only be changed between x2 and x1.

For this reason, if the photodiode is made smaller, the distance between each stopper must be finely adjusted accordingly, which takes time and effort. Furthermore, there is a natural limit to the adjustable range, and there is a drawback that the photodiode cannot be made very small.

Next, further drawbacks will be described while explaining the operation shown in FIG. 10 mentioned above.

In FIG. 10, 1 indicates the light emitting diode (hereinafter LED).
) 2 is the drive current setting resistor, 3.4 is the photodiode (hereinafter referred to as PD), and 5.6 is the resistor, and the resistance values of each are equal (R5 = R6).
). 7 is a coil used to return the pendulum displacement within the accelerometer, and 8 is a resistor for detecting the current flowing through the coil 7. Acceleration is measured by reading the voltage across this resistor. 9 is an operational amplifier.

In the above configuration, when the power is turned on, the power supply voltage Vcc
occurs, current flows to LED2 through resistor 7, and LED
D2 emits light. This light enters the PD 3.4 through the slit 50 (see FIG. 11). At this time, the outputs V and -B of the operational amplifier 9 are respectively 1p3 (PD3) and 1p3 (PD3),
When p4 (PD4), VA-8=R5x (i p3- i p4). The resistor 5.6 is a current amplifying resistor, and when the voltage generated there is applied to the coil 7, it works to return the pendulum displacement to its original state.

Also, as shown in FIG. 13, when looking at the relationship between the moving distance of the slit 50 and its displacement output V A -B,
Normal servo between X4 (output proportional to displacement is generated)
The area between X2, Xs, and X4-X+ is an area where the directionality of the servo output (that is, a force that returns the servo displacement to its original state is generated) is protected, and as time passes, it will return to the normal servo area. be able to. Above X1 and below X2, the servo output becomes rOJ, and it is no longer possible to return to the normal servo range.

Regarding the relationship between the displacement output V a-s, the moving distance of the slit 50, and the size of PD, the moving distance is roJ
When (=displacement x of slit 50=xo), the amount of light incident on each PD becomes equal, and the displacement output becomes VA-B=O. After that, considering the case of moving in the direction of the arrow, from Xo to x4, the amount of incident light to PD4 gradually increases, and the amount of incident light to PD3 gradually decreases, so the displacement output V A-a will increase. Between x4 and x, the slit 50 is on the PDJ, and the amount of received light proportional to the area of the slit portion 50a is output as a constant value, and near XI, the slit 50 (slit portion 50a)
decreases as it gradually deviates from PD4.

At X1 or higher, the slit 50 is no longer on the PD 4 and the amount of light incident on the PD 4 disappears, so V, . . . =O. Regarding x3°x2, etc., the relationship is that PD4 and PD3 are reversed.

Currently, the stoppers 52 and 53 shown in Fig. 11 are missing, or the fine adjustment of the distance between the stoppers has not gone well, and the distance between the stoppers is greater than the light receiving area (X2-X1 in Fig. 13).
In this case, there is no guarantee that the pendulum 51 is within the servo range when the power is turned on, and there is a possibility that it is outside the servo range, so control is required to bring it within the normal servo range. Also, if excessive acceleration is input due to an impact, etc., it may exceed the servo area and enter a dead zone of Xl (x2) or more, and in this case, there is a drawback that the servo will no longer be applied. .

(Object of the Invention) The object of the present invention is to solve the above-mentioned problems, to eliminate the possibility that the servo becomes disabled even if the servo falls outside the servo range due to an impact, etc. It is an object of the present invention to provide a displacement controller that eliminates the need for fine adjustment of the members and also allows normal servo operation even if the light receiving area of a light receiving element used for displacement detection is made small.

(Features of the Invention) In order to achieve the above object, the present invention includes a displacement detection means for detecting whether the displacement is outside the servo range, and a displacement detection means for detecting whether the displacement is outside the servo range, and a displacement detection means for detecting whether the displacement is outside the servo range, and A control means is provided to forcefully bring the displacement outside the range into the servo range, so that when the outside of the servo range is detected, the displacement is forcibly brought into the range where the servo can be applied. It is characterized by

(Embodiment of the invention) FIG. 1 is a circuit diagram showing an embodiment of the present invention.
The same parts as in the figure are given the same reference numerals.

In Fig. 1, 10 to 12 are turned ON when the control input is at the "H" level, and turned OFF when the control input is at the "L" level.
13 is an AND gate, 14.
15 is an inverter, 16 and 17 are OR gates, 18.1
9 is a comparator (hereinafter referred to as COMP) to which the reference power supply V ref3°V ref4 is applied, and 20 is a zero crossing detector (hereinafter referred to as ZCD), which keeps the “H” level for a certain period of time only when the input signal crosses the O level. Outputs the following. Reference numerals 21 and 22 are reset priority flip-flops (hereinafter referred to as FF), and when a rising pulse is input to the S terminal, the Q output becomes the "H° level," and the "H" level is applied to the R terminal.
When the "level" is input, it enters a reset state and its Q output becomes the °L level.

23 is a resistor, 24 is a switch linked to power-on (hereinafter referred to as SW), and 25.26 is a circuit that outputs a pulse for a predetermined period of time from the moment the input signal becomes "L" level (hereinafter referred to as O8). 60 is the OR gate.

Next, the operation will be explained with reference to the timing chart of FIG. 2.

First, it is assumed that the pendulum (not shown) (the position of the slit) is in a state of x2 or less when the power is turned on. When 5W24 is turned on in conjunction with power-on, a corresponding signal is input to 0325, and 0S25 outputs an "H" pulse for a predetermined period of time. Furthermore, at this time of power-on, FF21
．． A one-shot pulse is input to the FF 22 through the OR gate 60, and it becomes a reset state, and each Q output becomes “L”.
The “H” pulse is input to the OR gate 16, and therefore the OR gate 16 also outputs the signal, so the analog 5W 12 is turned ON and the AND gate is input via the inverter 14. 13 is set to "L".

This "L" output turns off the analog 5WIO, and the output of the operational amplifier 9 to the coil 7 is cut off. By turning on the analog 5W12, a power supply voltage Vcc (here, Vcc is a positive power supply voltage and Vss is a negative power supply voltage) is applied to the coil 7. When a positive power supply voltage Vcc is applied to the coil 7, a force is generated that makes the pendulum more negative than The value is not determined based on the balance with the light receiving area, but it is simply a rotation limiting member that does not require accuracy in terms of distance and can be wider than the light receiving area), and remains stopped at that position.

Thereafter, when the output of 0325 changes from "H" to "L", 0826 starts to output "H" for a predetermined period of time as shown in FIG. This output is applied to the analog 5W11 via the OR gate 17, and the analog SW is turned on. Further, this output is applied to the analog 5WIO via the inverter 15 and the AND gate 13, and the analog 5W10 is turned off. Turning on the analog 5WII
As a result, the negative power supply voltage Vss is now applied to the coil 7, and a force in the opposite direction to that previously is generated. This force causes the pendulum (slit) to gradually move in the positive direction, passing through X2 and then passing through the 0 level (xo).

At this time, as shown in FIG. 2, the displacement output VA-8 of the operational amplifier 9 starts from the 0 level, goes to the negative (-) direction, and then draws a curve that rises toward the 0 level. Then, it enters the normal servo area and the displacement output VA-B
When crosses the O level, the ZCD 20 outputs a short pulse of a predetermined time and resets the 0S26. Therefore, the output becomes "L", the analog 5W11 is turned off, and the analog 5WIO is turned on, thereby connecting the displacement output V A-B of the operational amplifier 6 to the coil 7, thereby enabling normal servo operation.

The explanation so far has been given when the pendulum is at a displacement of x2 or less when the power is turned on, but it is also conceivable that the pendulum is at a position of x1 or more. In this case, during the operation of 0325 (when outputting "H"), the displacement of the pendulum passes through X 1 + X 4 and changes to the O level of Cross the vicinity. At this time, ZCD20 transmits a short pulse to 0325.26, which puts them in the reset state (resetting O325 causes its Q output to go from "H" to "L"°, thus OS, 2
6 is about to start, but a reset pulse with sufficient time to prevent this is applied to 0326).

After that, normal servo operation can be started.

Also, when the pendulum is at a halfway position other than the above, xO is the displacement output VA-B and the reference voltage V re :
5 (described later), it is possible to enter the normal servo range by crossing the 0 level during the operation of 0325. When xo is less than the reference voltage V ref5, x2
It will go to the following position and stop, and will enter the normal servo area at the time of operation 0326.

Here, the ZCD 20 will be explained.

This circuit configuration is shown in FIG. 3, and will be explained below with reference to the timing chart in FIG. 4. First, the inversion reference level (V re5.
ref6) is provided near the ○ level of the displacement output VA-8 (V ref3>V ref5>O>V
ref6>Vref4).

(When the displacement output V A-a crosses the 0 level from 0 to -) First, COMP41 changes from "L" output to "H" output, and "H" is applied to the D terminal of the latch circuit 45. Ru. After that, when the displacement output VA-8 crosses the reference power supply V ref6, COMP42 changes from "H" to "L", and this falling edge is input to the CK terminal of the latch circuit 45. The Q output of the latch circuit 45 becomes "H", and the 0S47 outputs a pulse for a predetermined time from the rising edge of this "H" output. Also, this pulse output is input to the R terminal of the latch circuit 45, so that the The latch circuit 45 is reset and its Q output is set to "L".

(When the displacement output VA-II crosses the 0 level from - to 10) When the displacement output v A-e passes the reference voltage V ref6, CO'MP42 changes from "L" to "H" and latches. “H” is applied to the D terminal of the circuit 46.

Thereafter, when the displacement output V A-a passes the reference voltage V ref5, COMP41 changes from "H" to "L" and is input to the GK terminal of the latch circuit 46.

This falling edge causes the Q output of the latch circuit 46 to become "H", and the 0348 outputs a pulse for a predetermined time from the rising edge of this "H" output. Further, this pulse output is input to the R terminal of the latch circuit 46, so that the latch circuit 46 is reset.

As described above, when the displacement output V A-8 passes near the 0 level, 0347 (or O548) is activated, and the output here is sent out as is through the OR gate 49.

Next, a case will be described in which the normal servo range is exceeded due to an impact or the like during normal servo control after the power is turned on.

1) Now, if we assume that the impact moves in the positive direction as the direction of displacement
The output of FF21 changes from "L" to °H", and the S of FF21 changes.
input to the terminal. By inputting this rising edge, the Q output of the FF 21 becomes "H", so that the analog 5W12 is turned on via the OR gate 16, and the analog 5WIO is turned off via the inverter 15 and the AND gate 13. Analog 5W12 ON
As a result, the power supply voltage Vcc is applied to the coil 7, and a force in the negative direction is generated. Even after the force in the negative direction is generated, the impact in the positive direction continues to be strong enough to overcome the force in the negative direction, and when it reaches a range exceeding xl, the output of the displacement output VA-8 becomes 0 (in Figure 2). , point α on the graph of displacement output V^-8). Afterwards, when this impact subsides and the negative force by the coil 7 becomes effective, the slit begins to move and the displacement output V
A-e rises from the O level, passes through a constant value region, and then begins to fall again, entering the normal servo region X3-X4. Thereafter, when the displacement output VA-B passes near the 0 level, the ZCD 20 operates, transmits the pulse output to the FF 21 via the OR gate 60, resets the FF 21, and sets its Q output to "L". Now you can apply normal servo again.

2) Case 1) above is when the displacement X moves in the positive direction due to an impact, but if it moves in the negative direction, the flow of operation is similar to 1). That is, the COMP 19 operates, the FF 22 operates, and a force is generated in the positive direction in the coil 7 to bring it into the normal servo range.

In the first embodiment, two PDs are used as some elements of the displacement detecting means, but FIG. 5 shows an embodiment in which the number of PDs (only 4 in this example) is one element. The arrangement of the optical system at this time can be considered to be the same as in FIG. 12, with PD3 removed.

In FIG. 5, 36 is a constant current circuit for setting the reference position of displacement (this output is assumed to be IC), and the output VA of the operational amplifier 9 is VA = (ip4-ic), assuming that the photocurrent of PD4 is ip4. It becomes XR5. IC is set, for example, to the value of the photocurrent generated when light corresponding to half the area of the slit portion 50a is incident on the PD 4. The relationship between the displacement X and the displacement output VA at this time is shown in FIG.

In FIG. 6, xo is the reference position, and 1p4=ic
It's time. When the displacement When half of the area becomes the light receiving area, it passes through X. Then, when the displacement X further moves in the positive direction, the light no longer hits the PD through the slit, resulting in a constant negative output value. At this time,
The displacement output is VA=-icXR5. Conversely, when moving in the negative direction from the reference position XO, the displacement output VA gradually decreases, and when it exceeds x7, it reaches a constant negative value (the same value as VA=-icXR5). If, for some reason, the slit enters a range exceeding x5, the displacement output VA becomes a negative output, and this output causes the coil 7 to generate a force in the positive direction, pushing it further in the positive direction, and reaching the limit value at which it can rotate. It will stop there.

The area between Xt and Xt is a normal servo area.

X a X @ between, x? The following is not a normal servo area, but as time passes, the normal servo area - (X)
This is an area (pseudo servo area) that can be entered (between X and s).

After all, in this case, unless the displacement X continues to exceed x6, normal servo will not be applied.

The operation of the above configuration will be explained with reference to the time chart shown in FIG.

1) Now assume that the pendulum is in a range exceeding xIl when the power is turned on. When the SW 24 is turned on in conjunction with power-on, the 0335 outputs an "H" pulse for a predetermined period of time. Due to the generation of this "H" pulse, the analog 5W 28 is turned on via the OR gate 32, and the inverter 29
The analog 5W27 is turned off via the . By turning on the analog sw28, the coil 7 is supplied with the power supply voltage Vcc.
is applied, generating a force in the negative direction. Due to this force, the slit gradually turns from the child direction to one direction, and Xs, Xs
,Xo,X? , and moves until it hits the rotation restriction member in one direction. Note that the one-shot pulse time may be set to be longer than the time required to become X5 or less. After that, by entering the pseudo servo area,
The normal servo range can be entered over time.

After that, the output of 0835 becomes “H” after a predetermined period of time has elapsed.
By going “L” from
F, and analog 5W27 turns ON. As a result, the displacement output VA of the operational amplifier 9 is applied to the coil 7, pseudo servo starts to be applied, and the normal servo range can be entered.

Note that the reason why the output of 0835 is input to the R terminal of ON31 is to prevent GOMP30 from operating depending on the displacement output VA when the power is turned on, and from outputting pulses from 0831.

2) If the servo goes out of range due to impact,
As shown in the waveform in FIG. 7, the displacement Outputs a pulse for a time of .

This pulse passes through the OR gate 32 and the analog 5W2
Turn on 8 and turn off analog 5W27. As a result, the power supply voltage Vcc is applied to the coil 7, and a force that returns the slit in the negative direction is generated. If the force caused by the impact is greater than the force generated in the coil 7, the slit will further move in the positive direction due to this impact, and will stop at the limit value where it can rotate, that is, when it hits the rotation restriction member. .

This rotation regulating member is not related to the size of the PD as in the case of the previous two-element case, and may be a rough member.

The waveform representing the state of the displacement X at this time is the part β in FIG. After that, this shock subsides and the force exerted by the coil 7 (
(with power supply voltage Vcc applied), the displacement X moves in one direction. On the way, the displacement output VA passes through the normal servo area (the part represented by γ) by - degrees and reaches X7 on one side.
Go to the following position and stop.

After that, when the Q output of ON31 changes from "H" to "L", pseudo servo starts to be applied, moves in the positive direction, and settles into the normal servo range.

3) In 2) above, the servo abnormality is detected by the GOMP 30, but it is also possible to enter the normal servo range by detecting that the output of the displacement output VA continues to be at a predetermined level of -.

(i) In FIG. 6, when the displacement

(ii) When the displacement X is greater than or equal to XS, the output of the displacement output VA remains at the lowest limit value. (When displacement X is more than X6,
The output of the displacement output VA is negative, so the coil 7 continues to generate force in the positive direction, and the rotation regulating member (large distance)
It hits and stops. The displacement output VA at this time takes the lowest limit value. ) It is possible to distinguish between (i) and (ii) from the temporal relationship between them, and if the displacement output VA continues to be at the lowest limit value, it can be determined that the displacement It is sufficient to generate a force in the coil 7 that falls within the servo range. This embodiment is shown in FIG. The configuration shown in FIG. 8 is obtained by replacing the configuration within the dotted line A in FIG.

The operation shown in FIG. 8 will be explained with reference to the time chart shown in FIG. 9.

The displacement output VA is input to COMP37, and the displacement output V
When A is below the reference voltage Vref2 (see FIG. 6 for this level), the output of the COMP 37 becomes "H" and is input to the counter 38.

When the "H" input continues for a predetermined time (tl) or more, the counter 38 outputs "H", which is input to the ON 39. 0839 outputs a pulse for a predetermined time in response to this rising input,
A force in the negative direction is generated in the coil 7 in FIG. 5, and the subsequent discussion is the same as in the case 2) above.

The inverter 40 in FIG. 8 is for resetting the state of the counter 38, and continues to reset as long as the servo is in normal state, that is, as long as the output of COMP37 remains "L", and the output of COMP37 remains "L". This is to start the time counting operation of the counter 38 from the moment the signal reaches "H".

The time 1+ measured by the counter 38 may be set to a time width long enough to avoid this, since the displacement output VA may become lower than the reference voltage V ref2 due to an impact or the like. Further, in the second embodiment, the countermeasure circuit etc. (resistor 23, 5W24, 535) at power-on can be made unnecessary.

This is because, when the power is turned on, if the displacement X continues to be at a value of x5 or more, the circuit shown in FIG. 8 operates and attempts to enter the normal servo range.

According to this embodiment, by detecting that the servo is outside the servo range, the servo range is returned to normal, so it is no longer possible to go out of the servo range due to an impact and become unable to perform servo. . In addition, this eliminates the need to fine-tune the stopper for limiting the servo range, simplifying handling, and furthermore, allowing normal servo operation even if the area of the photodetector (PD) is reduced, making it more economical. Increase.

(Correspondence between invention and embodiment) In this embodiment, COMP 18, 19 and 5 in FIG.
COMP30 in the figure. COMP37 in Figure 8, counter 3
8. The inverter 40 serves as the displacement detection means of the present invention, and the FF2
1, 22, analog 5WIO~13, and gate 13
, Inverter 14°15, ZCD20, ○S3 in Fig. 5
1, analog 5W27, 28, inverter 29, 5th.
0339 in Figure 8, analog 5W27, 28, and inverter 29 are the control means, and resistor 23.5W24.03 in Figure 1
25, 26, and the resistor 23.5W24.0835 in FIG. 5 correspond to the displacement control means, respectively.

(Modification) In this embodiment, an LED, a PD, and a slit were used as displacement detection means, but the present invention is not limited to this.
A phototransistor may be used instead of a photodiode, or a magnetic sensor such as an MR element may be used to apply the above description.

(Effects of the Invention) As described above, according to the present invention, the displacement detection means detects whether the displacement is outside the servo range, and when it is detected that the displacement is outside the servo range, the servo A control means is provided to force the displacement outside the servo range into the servo range, and when the servo is detected to be outside the servo range, the servo is forced into the range where the servo can be applied. Even if the servo is out of the range due to other reasons, it is possible to eliminate the possibility that the servo will no longer be possible.
Furthermore, it is possible to provide a displacement controller that can perform normal servo even if the light-receiving area of the light-receiving element used for displacement detection is reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the first embodiment of the present invention, FIG. 2 is a time chart thereof, FIG. 3 is a block diagram showing the configuration of the ZCD shown in FIG. 1, FIG. 4 is a time chart thereof, and FIG. The figure is a circuit diagram showing the second embodiment of the present invention, FIG. 6 is a diagram also showing the relationship between displacement output, displacement, and reference voltage, and FIG. Figure 8 is a block diagram of a different configuration within the dotted line A in Figure 5, Figure 9 is its time chart, Figure 10 is a circuit diagram showing the conventional electrical configuration, and Figure 11 is the same mechanical configuration. Figure 12 showing
13 is a diagram similarly showing the positional relationship of the optical system, and FIG. 13 is a diagram similarly showing the relationship between displacement output, displacement, and reference voltage. 10.11.12... Analog switch, 13
......AND gate, 14.15...Inverter, 16.17...OR gate, 18.
19... Comparator, 20... Zero crossing detector, 21.22... Flip-flop, 23... Resistor, 24...
Switch, 25.26...One-shot circuit,
27.28...Analog switch, 29...
...Inverter, 30...Comparator, 3
7...Comparator, 38...Counter, 39...One-shot circuit, 40...
...Inverter.

Claims (2)

[Claims] (1) A displacement controller used in devices that measure physical quantities by detecting displacement and applying a servo so that the displacement returns to the reference position, and detects whether the displacement is outside the servo range. A displacement controller comprising a displacement detection means and a control means for forcibly bringing a displacement outside the servo range into the servo range when it is detected that the displacement is outside the servo range. (2) The displacement controller according to claim 1, further comprising a displacement control means for controlling the displacement within a servo range when the power is turned on.