JPS58207102A - Digital servo device - Google Patents

Abstract

PURPOSE:To ensure a stable control operation, by producing a sawtooth wave signal at a time position corresponding to each pulse interval based on a pulse train which is detected in the form of the driving information of a motor and controlling the motor driving with this signal information. CONSTITUTION:A shift information detecting circuit 10 has an optical linear encoder 11 to deliver triangular wave signals AS and BS containing phases A and B which show the revolving direction and the number of revolutions of a DC motor 1. These triangular wave signals are fed to a direction discriminating circuit 12. Then the revolving direction of the motor 1 is discriminated from the difference of phase, and at the same time the number of revolutions is detected from the number of triangular waves per unit time. The pulse trains CP of the number proportional to the detecting frequencies are delivered from the circuit 12 for each revolving direction and then fed to counters 13 and 14 respectively. These counters count the pulse trains and deliver the count values as shift informations CG and DG of an object.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical details of the invention] The present invention relates to a digital serve device that drives and controls a device for determining semiconductor devices, for example, in a semiconductor manufacturing process at high speed and with high precision.

[Technical background of the invention and its problems]

Conventionally, this type of sensor is used as a device, for example, as shown in FIG. 1, rotation information of a DC motor 1 that moves an object, that is, information on the current position of the object, is detected by an encoder 2 and a direction determination circuit 3, and the detected information is is compared with the information on the position where the object should be located, that is, the reference position information, in the comparison calculation circuit 4 to find the difference, and the deviation counter 5 generates control information to make this difference zero, which is converted into D/A. After converting the analog signal into an analog signal in the servo drive circuit 6, the signal is applied to the drive circuit 7, and the servo drive circuit 2 drives and controls the DC motor 1 to position the object.

However, in a device with such a configuration, the servo drive circuit 7
is constructed from analog circuits, so offset,
It is easily affected by drift and noise, and therefore -?
This system has the disadvantage that the operating stability of the system is low and that the adjustment of the circuit becomes extremely complicated.

On the other hand, the positioning accuracy in the above-mentioned device is mainly determined by the position resolution of the encoder 2. In the case of a linear encoder, the encoder is placed opposite the moving slit 2 that moves with the object as shown in FIG. Two fixed slits 2b and 2C are arranged, respectively, and the slit arrangement states differ by 90 degrees from each other, and the light sources 2d and 2θ output light passing through the moving slit 2a and the fixed slit 2, respectively, are fixed to the moving slit 2a and the fixed slit 2. The slit 2 is configured to detect the movement position information of the object by receiving light with the light receivers 2f and 2g for each 2B.

Therefore, the light receiving output AS of the light receivers 2f and 2g.

BS is a moving slin) 2m window and fixed slit 2, 2
It is maximum when the windows of B are completely aligned with each other, and it is minimum when the windows of each -1 slit are misaligned with each other by 180 degrees. Since the waveform changes approximately linearly in the middle, the continuous waveform becomes close to a triangular wave as shown in FIG. 3, for example. In addition, each light receiving output As, BS is
Fixed Surin),? Since the positions of A and 2B are shifted by 90 degrees from each other, for example, when moving the moving slit 2m in the direction of the arrow ■ in the figure, the received light output A is as shown in Figure 3 ■.
If the phase of the received light output BS is delayed by 90 degrees with respect to s, then the received light output BS is also 90' out of phase with respect to the received light output As, as shown in Fig. 3. will proceed. Therefore, by checking the number and phase relationship of the triangular waveforms of the received light output As and BS, the amount of movement of the object and its direction can be detected.

Conventionally, as the detection means, for example, each light receiving output As
, BS is binarized based on its average level, and these two
By combining the valued signals and applying them to the r-ted monostable multi-vibration pulse train, a positive or negative pulse train with an interval of 900 is obtained, and from the number of this pulse train, the amount of movement of the object can be calculated. The direction of movement is detected from the polarity of the pulse train. The information detected in this way is directly used to create drive control information for the motor 1. Therefore, the motor 1 is driven with a positional resolution corresponding to the spacing between the above-mentioned russet rows. In other words, the position resolution of such a serve device is determined by the spacing between the slits of the encoder 2.

Here, the interval between the slits is usually at least about 8 μm, and when the direction discrimination circuit 3 detects the slit, it is divided into four, which corresponds to 2 μm per pulse. When a server having position resolution resources as described above moves and controls an object using a device, the object will vibrate slightly in the range of ±2 μm near the moving target point. This micro-vibration is extremely undesirable, especially when wire-bonding semiconductor devices, because it often causes various problems such as shifting of the bonding position and unstable bonding operation. In the serve device, boo 2 near the target point
However, there is a tendency to have a large tendency to have sex, but
In the conventional device mentioned above, the minute vibration near the target point tends to be more than ±1. It was not possible to set the clamper too tightly, and no improvement in stability could be expected.

[Object of the Invention] The present invention aims to improve the stability of control operations by reducing the effects of offset, drift, noise, etc., and suppresses the occurrence of minute vibrations near the target point, thereby reducing the occurrence of crushing caused by large sensors. The purpose is to provide a digital servo device that is possible.

[Summary of the invention]

In order to achieve the above object, the present invention configures a motor drive circuit system with a digital circuit, and creates a sawtooth pattern at a time position corresponding to each pulse train based on a pulse train detected as motor drive information. Wave signal information is generated, sawtooth wave signal information is inserted into drive control information as a drive amount control element, and the motor is drive-controlled based on this drive control information.

[Embodiments of the invention]

FIG. 4 is a block diagram showing the configuration of a digital servo device according to an embodiment of the present invention. an arithmetic control circuit 20 that creates information for driving the DC motor 1 from the DC motor 1;
A morse width modulation circuit 30 performs morse width modulation based on motor drive control information, and drive power is supplied to the DC motor 1 in accordance with the pulse signal f'L output from this morse width modulation circuit 30. Rotation information of the DC motor 1 obtained by the motor drive circuit 40 and the movement information detection circuit 1o is introduced, sawtooth wave information is generated from this information, and this is used as correction information for the motor drive control information in the arithmetic control circuit. The movement information detection circuit 10 is composed of a sawtooth wave information generation circuit 5o that supplies the information to the optical IJ near en-y
First, the encoder 11 generates triangular wave signals A and S consisting of A and B phases that intersect the rotation direction and rotation amount of the DC motor 1.

BS is output, and the triangular wave signal As and BS are introduced into the direction determining circuit 2, where the rotational direction of the motor 1 is determined based on the phase difference, and the amount of rotation is detected from the wave number per unit time of the triangular wave. do. Then, a number of lines CP and CP proportional to the number of detections are output from the direction discrimination circuit 12 for each rotation direction (positive direction, negative direction) and guided to the collar 73113.14, and these counters 13. Count each in Step 4 and use the counted values as object movement information CG.
, DG in the form of, for example, 8-bit parallel signals.

FIG. 5 is a diagram showing an example of the configuration of the direction determining circuit 12. First, the direction determining circuit 12 receives the A-phase and B-phase triangular wave signals from the encoder 11 (FIG. 10 AS,
BS) are input to the controllers 15 and 16, respectively, and the reference level BtI/Ci determined as the average value of the triangular wave signals AS and BS is set to 2 as shown in FIG.
Value. Then, each of these binary outputs As', BS
' and its inverted binary outputs AS' and BS' are mutually (C combined) to generate each gate-controlled monostable multivibrator 7.
7 and their respective outputs to OR gate circuits 18 and 19f.
The first
CP and DP in FIG. 0 indicate the outputs (Nocrustar 11) of the OR gate circuits 18 and 19.

Now, there is a sawtooth wave information generation circuit 5o (rs), a sawtooth wave generation circuit 51 that generates a sawtooth wave signal KS, and an analog denotal ( A/i)) converter 52.

The sawtooth wave generation circuit 51 generates a sawtooth wave signal KS as follows.
occurs. That is, the output/Grus sequence CP of each OR gate circuit Ill, 19 of the direction discrimination circuit 12,
The timing of occurrence of DP is t as shown in FIG. + tI + t21t3+... and tNO
+ tNl r tN2 + tN3 + '..., then the calculations shown in Tables 1 and 2 below are performed for each cholera sequence CP and i4 sequence DP between each cholera generation timing.

Table 1 Table 2 If such calculations are performed, the first
A sawtooth wave signal can be generated as shown in Figure 0 KS.

FIG. 6 shows an example of a circuit for performing the above calculation. In this circuit, a triangular wave signal AS and an inverted signal port obtained by inverting the polarity of this signal As by an inverting amplifier 53 are selectively guided to an operational amplifier 55 by an analog switch 54, and a triangular wave signal BS and this signal BS are fed to an inverting amplifier 56. Connect the signal port whose polarity has been reversed with analog switch 5.
7 is selectively led to an operational amplifier 55. Then, these signals are operated on by an operational amplifier 55, and the output is outputted as a sawtooth wave signal KS via an inverting amplifier 58.

Here, each of the analog switches 54 and 57 is configured to perform a switching operation according to the switching control signals ASW and BSW, respectively, and the signals ASW and BSW are set to "H".
Signal shoulder when level.

Select the signal I side, and when the signal is at the "L" level, the signal As,
Selecting the signal BS side 8 Figure 7 shows a circuit for generating each of the above switching control signals ASW and BSW. Four AND circuits 61° to 64 that generate H# level, and these AND circuits 61. Eight AND gate circuits 65.-, 72 conduct only when @H'' level output is supplied from ~, 64 and pass the pulse strings CP, DP'i, and these 111% AND gate circuits 65.-, 72 conduct. Two 7-lip flop circuits 73. whose states are set by the pulses that have passed through the gate circuits 65. to 72.
The sawtooth wave generating circuit 51 is constructed from these arithmetic circuits (FIG. 6) and the switching control circuit (FIG. 7). With this kind of configuration,
For example, 7 russ generation interval t. -tl, the binary signal A
s' is ``H'' level (As'Ul), B S' is 1L#
level (BS'=O), a signal of "H# level" is output from the AND circuit 64 in FIG. are in the reset state, and the switching control signals ASW and BSW of L# level are outputted.Then, each analog switch 54 and 57 of the arithmetic circuit (Fig. 6) outputs the signal A, S and the signal BS, respectively.
In order to switch to the side, the signal As and the signal BS are respectively supplied to the operational amplifier 55, and the calculation (AB+BS) is performed, and as a result, the sawtooth wave signal KS as shown in FIG.
is generated in a pulse generation period tO to t. Further, in the noise generation period t1 to t, both the binary signals AS' and BS' are at the H# level (AS'=1, BS
'=1), so only the AND circuit 61 outputs "H".
AND gate circuit 65.72 when the level signal is generated
are conductive, and as a result, the free lag flop circuit 73
A set pulse is applied to the switching control signal ASW to -H.
Since no pulse is applied to the flip-flop circuit 74 even when the switching control signal BSW reaches the 1L level. Therefore, each of the analog switches 54 and 57 of the arithmetic circuit has the switch 54 set to the signal quality side,
Also, since the switch 57 is set to the signal BS side,
The signal port and the signal BS are respectively applied to the operational amplifier 55, and as a result, the operational amplifier 55 performs the calculation (AS+BS) to produce the sawtooth wave signal K as shown in FIG.
S is generated. Similarly, Noyalus occurrence interval t, ~
Even after t3 and after tso ``''' t, the switching control signals ASW and BSW are output according to the conditions of each section, and signal calculations are performed, and the sawtooth wave signal KS is output.
is generated.

Although the sawtooth wave signal KS generated as described above contains non-linear components as shown in FIG. 11, it can be regarded as a straight line approximately. is a C processor consisting of a microprocessor.
P, U 2J, a ROM 22 in which an object movement control program and reference position information are stored, a RAM 23 for storing information introduced from the outside and calculated values, the counters 13, 14, and the pulse width modulation circuit. It consists of an l1024 for inputting/outputting information to and from 30, etc., and a driving clock generator 25. and,
The arithmetic control circuit 20 performs arithmetic control according to the following procedure. That is, after initializing the system, the CPU 2.1 receives a clock pulse (for example, 1 kt(z) CP1) from the clock noise generator 25 and inputs it to the interrupt terminal. Each time the movement information detection circuit 10 changes color/return 13,
The movement information CG and DG are introduced from 14, and the digitized sawtooth wave signal IG is introduced from the sawtooth information generation circuit 50.
will be introduced. Then, change the above movement information to the previous clock.
Compare the movement information introduced at the time of clock pulse CP1 input and find the difference, and -1j01 movement amount VFV 'e during input of clock pulse CP1.Here, this movement amount VF
Since V is the amount of movement per unit time, it can be regarded as the moving speed information of the object. Next, the CPU 21 determines the amount of movement VF.
V is added to the position information calculated at the time of inputting the previous clock pulse CPJ to obtain the current position information PFD, and this pr
ROM in advance? Reference position information PI stored in 2
Drive control information MGi for the motor 1 is generated in order to compare it with N and make the difference zero. This drive control information MG is
2 consisting of information that determines the direction of rotation (for example, 2 bits) and information that determines the amount of rotation (for example, 10 bits).
Of these, the information that determines the amount of rotation is information that determines the pulse width of the pulse signal for motor drive control. This information PW is obtained not only from an element corresponding to the difference between the current position information PFD and the reference position information PIN, but also from a velocity feedback element obtained from the object velocity information and the digitized sawtooth wave signal IC. For example, it can be obtained by the following equation.

Pw ”” KO (PIN PFD KI VFD
K2PIC) However, Ko: Time conversion coefficient: Speed feedback coefficient 2: Position insertion coefficient P2: Digitized sawtooth wave signal value 8 The CPU 21 uses the drive control information MGf Il obtained in this way.
The pulse width modulation circuit 30 generates clock pulses as shown in FIG. Two sets of counter circuits 32.3 perform down-count operation by the clock pulse CP2 of the counter 3.
It has 3. Of these counter circuits 32 and 33, the count circuit 32 is used to determine the drive pulse frequency of the motor 1, and every time the counter 32b counts a certain value set in the time constant register 32m, the flip-flop 34 is activated. Repeat the action of setting. On the other hand, the counter circuit 33 is used to determine the pulse width of the driving pulse, and the information Pw for determining the pulse width introduced into the time dependence register 33& is transferred to the counter circuit 32.
Each time a set output is generated, C5 is first introduced into the counter 33b. Then, when the information 2w has been counted, a signal is issued to reset the flip-flop 34. In other words, the set output generation period of the flip-flop 34 corresponds to the pulse width. The output pulse signal OP of this flip roller 7''34 passes through an AND gate circuit 35.36 to a motor drive pulse signal OP1.
It is sent to the motor drive circuit 40 as OP2. Here, these AND gate circuits 35 and 36 reciprocally turn on and off the dart according to the output of the flip-flop 37 whose state is set according to the information that determines the rotational direction of the motor 1 in the drive control information MG. This specifies the rotation direction of the motor 1.

FIG. 9 shows the configuration of the motor drive circuit 40, and shows the motor drive Sols OPM, OP, ? outputted from the Mors width modulation circuit 30. id and the rotational direction of the motor 1 are respectively introduced into converters 41 and 42, and after being converted from 5v to 8v by the converters 41 and 42, for example, the polarity is inverted by inverting amplifiers 43 and 44, and F E of the switching circuit 45 is carried out. T Q+ , supplied to Q 2 . On the other hand, the output noise signals OPM' and OP2' of the concentrators 41 and 42 are introduced into switch control circuits 46 and 47, respectively. These switch control circuits 46 and 47 receive the output signal OPI'.

Each of the photocazola 46g and 47IL is turned on and off according to the signal level of OP2', and the comparator 46b is turned on and off according to the on/off state.

47b outputs switching signals SPI and SP2,
These signals SPI and SP2 are supplied to FETs Qt and Q4 of the switching circuit 45, respectively. Note that these switch control circuits 46 and 47 have the same configuration, so only the configuration of 47 is shown in the figure and 46 is omitted.

Now, the switching circuit 45 is connected to the motor drive power supply (+
20V and -20V), the above FETs Ql and Q
, and a series circuit of FETs Q4 and Q2 are connected in parallel with each other, and a DC motor is connected between the intermediate points of each series circuit through the current detection resistor 51 in series. ing. In addition, each FETQ+
.

As Q4, a power MO8FET is generally used which has excellent frequency characteristics and can simplify the circuit.

Therefore, in such a motor drive circuit 40, when a signal 0PJ ("H# level 5V") for normal rotation of the motor arrives from the pulse width modulation circuit 30, the comparator 41 and the inverting amplifier 43 generate a signal for switching. A signal (for example, H" level 8V) is formed.

FET Q becomes conductive. At the same time, the switch control circuit 47 outputs a υ switching signal (for example, ``L'').
L'' level -5vz is formed and FETQt becomes conductive.As a result, DC
A power output is supplied to the motor 1, and the DC motor 1 performs normal rotation operation. At this time, voltage is supplied to the DC motor 1 in a pulsed manner, but the current that flows due to the actance of the DC motor 1 is almost continuous.
When , FETQs and Q4 are brought into conduction, and as a result, power output is supplied to DC motor 1 and D
C motor 1 rotates in reverse.

Next, the operation of the device configured as above will be explained.

The ROMK of the arithmetic control circuit 20 stores in advance a program for controlling the movement of an object, and the CPU 21 creates and outputs drive control information for the 11ff primary DC motor 1 according to the program. As a result, the DC motor 1 rotates according to the above information and moves the object.

Now, the moving state of this object is detected by the linear encoder 11 as the rotation direction and rotation amount of the DC motor 1, and is output from the direction discrimination circuit 12 as pulse trains CP and DP for each rotation direction.

And this one? The pulse sequences CP and DP are counted by counters 13 and 14, respectively, and converted into, for example, 8-bit parallel signals, which are supplied to a CPU (microprocessor) 21. Each time the clock pulse CPI is input as an interrupt signal from the clock pulse generator 25, the CPU 21 outputs the output information CG and DG of each of the counters 13 and 14 and the sawtooth wave information generated by the sawtooth wave information generation circuit 50. A wave signal IG is introduced respectively. Then, the various calculations described above are performed to create drive control information for the motor 1. Therefore, this drive control information includes a correction component based on the sawtooth wave signal IC.

Then, the drive control information output from the arithmetic control circuit 20 is transferred to the time constant register 33 of the Nockles width modulation circuit 30.
&, and the counter 33b counts the value specified by the drive control information to determine the pulse width of the motor drive/main pulse OP.

The motor drive pulses OP are output from the terminals corresponding to the rotational direction specified by the drive control information by the flip-flop 37 and the AND date circuits 35 and 36.
,? When is output, the above seven pulses OPI is sent to the motor drive circuit 40.

OF2 is converted into a form suitable for controlling the switching circuit 45 to form a switching circuit 4511p FETQ.

~lQ4 is selectively made conductive, thereby causing DC motor 1
The DC motor 1 is driven by supplying power output to the DC motor 1 .

Therefore, the DC motor 1 has movement information CG.

Although the DG itself is a step type that is affected by the slit width detected by the linear encoder 11, the slit width is changed by inserting a sawtooth wave signal KS as shown in FIG. 10 into the drive control information. In many cases, the drive is controlled by information that eliminates the influence of Therefore, the DC motor 1 is driven more smoothly and accurately than in the past, and as a result, operational reliability and stability are improved. Such an effect is especially caused by DC near the target position.
This is very effective in the so-called servo clamp state that the motor 1 has reached. That is, in this embodiment, the drive control information PW in this servo clamp state is K
, P, term becomes dominant, and the DC
The motor 1 will be driven and controlled.

Therefore, the DC motor 1 hardly causes any slight movement unlike the conventional motor, and operates extremely stably. In addition, by suppressing microtremors to an almost negligible level,
, vibration is less likely to occur even if the gain of the control system is increased.
Sarde clamp power increases significantly.

Moreover, in this embodiment, since the motor drive circuit 40 is configured to control the supply of power output to the motor 1 through a switching operation, the adverse effects caused by offset, drift, and noise are suppressed to an extent that does not cause any practical problems. .

As described above, in this embodiment, by adding the element of the sawtooth wave signal to the drive control information, the slight movement of the DC motor 1 is significantly reduced, thereby improving the alignment accuracy and operational stability. Furthermore, by configuring the drive control system with a digital circuit, it is possible to reduce the negative effects of offset, drift, and noise, and in combination with the suppression of the above-mentioned fine movements, it is possible to further improve the operational stability of the control system. Note that the present invention is not limited to the above embodiments. For example, an electromagnetic encoder may be used instead of an optical encoder, or a linear encoder may be used.
A rotary encoder may be used instead of just one. Further, an integral term related to the time of the PIN FPD may be added to the drive control information. In this way, the offset can be further reduced.In addition, each counter 1 of the movement information detection circuit 10 can be further reduced. , 14 may be configured with one up/down counter to simplify the circuit configuration. In addition, the configurations of the sawtooth information generation circuit, arithmetic control circuit, pulse width modulation circuit, and motor drive circuit can be modified in various ways without departing from the gist of the present invention5. [Effects of the Invention] As described in detail, the present invention configures the motor drive circuit system with a digital circuit, and generates sawtooth wave signal information at time positions corresponding to each pulse based on the cell train detected as motor drive information. The sawtooth wave signal information is inserted into the drive control information as drive control information, and the motor is drive-controlled based on this drive control information.

Therefore, according to the present invention, the influence of offset, drift, noise, etc. is completely reduced to improve the stability of control operation, and the generation of micro vibrations near the target point is suppressed, so that a large siren can generate a flanging force. It is possible to provide a Denotal Sade device that has the following characteristics.

[Brief explanation of drawings]

Figures 1 to 3 are for explaining the technical background of the present invention, and Figure 1 is a diagram of the conventional digital circuit. The block configuration diagram of the device, FIGS. 2 and 3 are for explaining the problems, and FIGS. 4 to 11 (d) are for explaining one embodiment of the present invention, and FIG. A block diagram of the 4-t digital servo device, Figure 5 is a circuit diagram of the direction discrimination circuit, Figures 6 and 7 are circuit diagrams showing the configuration of the sawtooth wave generation circuit, and Figure 8 is a circuit diagram showing the configuration of the sawtooth wave generation circuit. 1. DC motor , 10... movement information detection circuit,
20...Arithmetic control circuit, 30...Zero width modulation circuit, 4θ...Motor drive circuit, 50...Sawtooth wave information generation circuit Fang 8 Evil Fang 10 Prisoner 11

Claims (1)

[Claims] a motor for moving an object; a drive information detection circuit that detects the drive direction and drive amount of the motor and converts the drive amount into a pulse train for each drive direction and outputs the pulse train; The count value is used as the movement information of the object and 1. a movement information counter that outputs movement information from the movement information counter; a sawtooth wave generation circuit that generates sawtooth wave signal information between each pulse of the pulse train generated by the drive information detection circuit; to obtain the current position information of the object, compare this information with preset reference position information, and generate drive control information for the motor in order to bring the difference close to zero. A calculation control circuit for glogram control that inserts the sawtooth wave signal information generated by the wave generation circuit as a drive amount control element, and drive amount information and drive direction information that constitute the drive control information output from this calculation control circuit. a pulse width modulation circuit that performs pulse width modulation according to drive amount information and outputs the pulse width signals separately according to drive direction information;
A digital serve device comprising: a motor drive circuit that controls on/off a drive power supply path to the motor according to a pulse signal from the ij pulse width modulation circuit to drive the motor.