JPH0968639A - Drive controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the resolution of the moving direction of the member being driven and the position detection and to detect high frequency signals which have a same level as the case that a single phase photointerrupter is used by detecting the amount of the movement of the member using a twophase photointerrupter and controlling the member being driven based on the detected amount of movement. SOLUTION: While sampling and counting analog detected signals by a twophase photointerrupter with a waveform shaping or an A/D conversion, the mode, in which two detected signals from photointerrupters 4 and 5 are counted, is switched to the mode, in which either one of the signals are counted, during the start of the member being driven. Thus, a high resolution detection is accomplished right after the start of the member and the movement is not stable. Furthermore, the sampling follows even though the frequencies of the detected signals becomes higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device, and more particularly to a drive control device for detecting a moving direction and a position of a driven member by using a two-phase photo interrupter.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for detecting the movement of a driven member, for example, in an encoder for detecting the rotation amount and the rotation direction of a zoom photographing optical system of a camera, it is necessary to use a rough encoder in order to perform a highly accurate detection. There is one in which a means for outputting a signal and a means for outputting a fine signal are used in combination, and the movement of the driven member is detected based on the output from each means (for example, see Japanese Patent Laid-Open No. 5-215915). ). However, according to such an encoder device, the movement detecting means for the coarse signal and the movement detecting means for the fine signal have to be set at different positions, so that a space for arranging the movement detecting means is provided. Is required, and it is difficult to match the phase relationship between these two signals. Therefore, eliminating these problems, and by using a two-phase photo interrupter to monitor the lens movement during focusing and zooming of the camera, it is possible to determine the moving direction and improve the resolution of position detection. A photointerrupter is proposed (see Japanese Patent Laid-Open No. 7-49445). In addition, a method of A / D converting and reading the analog signal to read the analog signal from the photo interrupter is also known, and if the A / D converter built in the microcomputer is used, a comparator is not necessary. Therefore, the cost of the device can be reduced.

[0003]

However, according to the conventional photo interrupter described above, the two analog signals of the two-phase photo interrupter are waveform-shaped,
In the case of pulse detection, if scanning is performed by importing from the port of the microcomputer, it takes longer than the sampling cycle when detecting the output from the single-phase photointerrupter, so the sampling cycle becomes longer and the frequency of the photointerrupter that can be followed. Will fall. Further, even with the method of A / D converting and reading the analog signal described above, since it takes longer time than the sampling cycle when detecting the output from the single-phase photo interrupter, the sampling cycle becomes longer and the photo interrupter that can follow up. There is a problem that the frequency drops.

The present invention has been made in order to solve the above-mentioned problems, and a means for outputting a plurality of detection signals different from each other according to the movement of the same driven member, for example, a two-phase photo interrupter is provided. In the drive control of the driven member used, by switching the mode for counting the output from the interrupter during the driving of the driven member, the drive control as a whole, the moving direction of the driven member,
Another object of the present invention is to provide a drive control device capable of detecting a signal at a high frequency while improving the resolution of position detection.

[0005]

In order to achieve the above object, a drive control device according to the present invention is a drive control device for controlling the drive of a driven member, which drives the driven member. Driving means for detecting the movement of the driven member driven by the driving means, and outputting the first signal in response to the movement of the driven member, and the first signal output means in a phase different from that of the first signal output means. Second signal output means for detecting movement of the driving member and outputting a second signal in response to the movement; an A / D converter for A / D converting the first signal and the second signal;
A first count mode for counting both the first and second signals A / D converted by the D converter, and either the first signal or the second signal A / D converted by the A / D converter And a second count mode for counting the first signal and the second signal at the predetermined timing while the driven member is being driven by the driving means to count the first signal and the second signal. And a counting means.

In the above structure, the counting means switches the first counting mode to the second counting mode at a predetermined timing to count the signals. That is, for example, when the speed of the driven member is slow, the first signal and the second signal
Although the sampling can follow the frequency of the signal even if the counting operation is performed in the first count mode (two-phase photo interrupter) for A / D converting both of the signals and counting,
As the speed of the driven member increases, the time required for A / D conversion does not change, so if the 1st count mode remains,
Sampling cannot follow the frequency of the signal. Therefore, when the speed of the driven member is increased, the second count mode (single-phase photo interrupter) for counting with either the first signal or the second signal is switched to, so that the sampling can follow the signal frequency. Like As a result, it is possible to improve the resolution of detection of the moving direction and the position of the driven member as compared with the drive control device using the single-phase photo interrupter, and at the same level as the drive control device using the single-phase photo interrupter. It becomes possible to count the detection signals up to a high frequency.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A drive control device according to the present invention will be described below with reference to the drawings. FIG. 1 shows the first embodiment of the present invention.
It is a circuit block diagram when the drive control device 1 by an Example is applied to the imaging optical system of a camera. The microcomputer 2 controls the entire drive control device 1, and is connected to the motor driver 3 and the photo interrupters 4 and 5. The motor driver 3 controls the drive of the focus motor 6 and the zoom motor 7 based on the output from the microcomputer 2.
The photo interrupter (PI) 4 has a two-phase detection unit that detects the rotation of the focus motor 6 at different phases, and has a two-phase analog signal (hereinafter, these signals will be respectively referred to as P
IP1 and PIP2) are output to the microcomputer 2. These PIP1 and PIP2 are A /
A / D conversion is performed by the D conversion function, and pulses are counted by the counter 2a. This counter 2a is a PIP
It has a two-phase count mode that counts both 1 and PIP2 signals and a single-phase count mode that counts with either PIP1 or PIP2 signal. Similarly, the photo interrupter 5 also detects the rotation of the zoom motor 7, outputs two signals PIP3 and PIP4 to the microcomputer 2, and the signals are counted by the counter 2a.
Based on these PIP1 to PIP4, the microcomputer 2 detects the moving direction and position of the taking lens (not shown). The LCD 8 displays the photographing information of the camera based on the signal from the microcomputer 2.

Next, the relationship between PIP1 and PIP2 of the photo interrupter 4 will be described with reference to FIG. Since the same applies to the relationship between PIP3 and PIP4 of the photo interrupter 5, the case of PIP1 and PIP2 will be described as a representative. FIG. 2 is a diagram showing signal waveforms of PIP1 and PIP2. The photo interrupter 4 detects rotation of the focus motor 6 and outputs PIP1 and PIP2, but the phase difference between PIP1 and PIP2 is set to 90 degrees. The rotation direction of the focus motor 6 (movement direction of the photographing lens) can be detected by identifying which of the PIP1 and PIP2 phases is delayed or advanced. Similar settings are made for PIP3 and PIP4 of the photo interrupter 5.

Next, PIP1 (PI
The process of A / D conversion of P2) will be described. FIG. 3 is a diagram showing how PIP1 is sampled at regular intervals when A / D conversion is performed on PIP1. The analog signal PIP1 is A / D converted when input to the microcomputer 2, but a certain time is required for the microcomputer 2 to perform A / D conversion once. This time is about 20 according to the standard level microcomputer.
It is uS. Furthermore, since it takes about 30 uS for the microcomputer to process the value obtained by A / D converting PIP1, the time (Ta) required for A / D converting PIP1 once is about 50 uS. Becomes Therefore, the analog signal PIP1 input to the microcomputer 2 is sampled about every 50 uS.

[0010] Here, in order not to miss the peak of PIP1, A / D is performed at least twice between peaks and peaks.
If conversion is performed, 2 × Ta = 2 × 50uS = 1
A time of 00uS is required. That is, in terms of the frequency of the photo interrupter 4, 1/100 uS = 10 kHz
You will be able to follow up to z. When actually performing the processing, the processing is performed up to 9 kHz with a margin in mind.

Next, PIP1 and PIP2 for two phases are
A process for the D / D conversion will be described. Figure 4 (a)
(B) is a diagram showing how PIP1 and PIP2 are sampled at regular intervals. PIP1 and PI
When P2 is input to the microcomputer 2, the microcomputer 2 cannot perform A / D conversion on two channels (ch) at the same time.
A / D conversion is performed for each channel. As described above, since the microcomputer 2 needs about 50 uS to perform the A / D conversion once and process the value, the sampling is alternately performed in the PIP1 and the PIP2 every about 50 uS. However, if the frequency of the photo interrupter 4 becomes faster,
The time required for the microcomputer 2 to perform A / D conversion and value processing (T
Since a) does not change, sampling cannot catch up.

In order not to miss the peaks of the analog signals PIP1 and PIP2, assuming that A / D conversion is performed at least twice between the peak and the peak of each signal, 4 × Ta = 4 × 50 uS = 200 uS It takes time. That is, in terms of the frequency of the photo interrupter, it can only follow up to 1/200 uS = 5 kHz. In this case, processing up to 4 kHz is performed with a margin as in the above case. Therefore, P
The signals of both IP1 and PIP2 can be A / D converted when the frequency of the photo interrupter 4 is up to 4 kHz.

Next, referring to FIGS. 5A, 5B, and 5C, a signal (PI) output from the photo interrupter 4 when the focus motor 6 (also in the case of the zoom motor 7) is driven. Of the frequency and the A / D conversion method of the signal will be described. 5A and 5B are diagrams showing changes in the frequency of the output signal of the photo interrupter 4 when the focus motor 6 is driven, and FIG. 5C shows the drive time of the focus motor 6 and the output signal of the photo interrupter 4. It is the figure which showed the relationship of the number of counts. Now, assuming that the maximum frequency of the photo interrupter 4 reaches 8 kHz, as described above, the two-phase A that cannot be sampled by the A / D conversion method in the two-phase count mode (hereinafter referred to as two-phase A / D conversion). In order to perform D / D conversion, it is necessary to suppress the frequency of the detection signal by the photo interrupter to 4 kHz. However, in that case, the drive time of the focus motor 6 will be long. The greatest merit of using the two-phase photo interrupter is that even if an extra pulse occurs due to rattling or distortion of the mechanical structure when starting, stopping, or reversing the driving direction of the motor, that pulse Can be accurately counted by discriminating whether the pulse is in the forward direction or the pulse in the reverse direction. Further, the resolution of the photo interrupter 4 is increased. On the other hand, when the motor is rotating, the rotation is stable, and it is unlikely that the directions of the pulses suddenly reverse. Therefore, when the motor is rotating and the rotation is stable, PIP1 or PIP1
A / D conversion of only one of the signals of IP2 (hereinafter,
There is no problem in counting by performing single-phase A / D conversion).

For this reason, if the motor is rotated and then the two-phase A / D conversion is switched to the single-phase A / D conversion at a certain time (time when the rotation of the motor is stable), the above-mentioned merit is obtained. Photo interrupter 4
Even if the frequency of the detection signal due to becomes the maximum frequency, it can be followed.

As shown in FIG. 5A, the timing for switching from the two-phase A / D conversion to the single-phase A / D conversion is PIP.
It is conceivable that the frequency of 1 or PIP2 exceeds 4 kHz which is the maximum frequency at which two-phase A / D conversion by the photo interrupter 4 is possible. In addition to this, FIG.
As shown in (b), the switching timing is set after a lapse of a fixed time (T ₁ ) from the start of driving the focus motor 6, and after a lapse of a fixed time (T ₂ ) from the start of the drive stop operation of the focus motor 6, Phase A / D conversion to 2-phase A / D
It is conceivable that the timing for switching to conversion is used.

Further, as shown in FIG. 5 (c), two-phase A
The timing of switching from / D conversion to single-phase A / D conversion is fixed pulse (P
₁ ) After counting, and after the constant pulse (P ₂ ) is counted from the start of the drive stop operation of the focus motor 6, the single-phase A /
It is conceivable to set the timing of switching from D conversion to 2-phase A / D conversion. By switching between the two-phase A / D conversion and the single-phase A / D conversion and counting the pulses at a predetermined timing as described above, even if the two-phase photointerrupter is used, the conventional single-phase photointerrupter is used. With this, it becomes possible to detect signals up to the same high frequency as when reading signals. If the number counted by the single-phase A / D conversion is doubled, it becomes the same as the count number when the two-phase A / D conversion is performed. Therefore, the count value of the counter 2a is always counted by the two-phase A / D conversion. It will be the same value as when you did.

FIG. 6 is a circuit block diagram of the drive controller 1 according to the second embodiment. In the drive control device 1 ′, PIP 1 and PIP 2 of the photo interrupter 4 and PIP 3 and PIP 4 of the photo interrupter 5 are input to the microcomputer 2 via the waveform shaping circuits 11 and 12.
The waveform shaping circuits 11 and 12 are P, which are analog signals.
The IP1 to PIP4 are converted into digital signals. As a result, the microcomputer 2 takes in the digital signals PIP1D to PIP4D from the port and sequentially samples each signal.

Next, the relationship between PIP1 and PIP2 of the photo interrupter 4 in the drive controller 1'will be described. FIG. 7 shows signals PIP1D and PIP in which the analog signals PIP1 and PIP2 are digitized by the waveform shaping circuit 11.
It is the figure which showed the signal waveform of IP2D. As mentioned above,
The microcomputer 2 has a PIP from the photo interrupter 4.
1, PIP2 through the waveform shaping circuit 11, PIP1D,
Although input as PIP2D, the two-phase photo interrupter 4 is input as PIP1 as in the case of the first embodiment described above.
Since the phase difference between D and PIP2D is set to 90 degrees, the rotation direction of the focus motor 6 can be detected by identifying which of PIP1D and PIP2D is out of phase. Similar settings are made for PIP3 and PIP4 of the photo interrupter 5.

Next, with reference to the flow chart of FIG. 8, description will be given of processing in the drive control device 1'when checking the digitalized signals of PIP1D and PIP2D. When the signal is checked in the drive control device 1 ', first, PIP1D is High (hereinafter, referred to as H
, Or Low (hereinafter, referred to as L) (# 1), and then whether the previous PIP1D is L or H is checked (# 2, # 3). # 1
When PIP1D is H and PIP1D is L in # 2 (change from H to L), and PIP1D is L in # 1 and PIP1D is H in # 3 (change from L to H) The counter value of PIP1D of the counter 2a is 1
Increase (# 4). After the above processing is completed, similarly, PIP2D is checked in # 5 to # 8, and PI is checked.
When the count value of P1D or PIP2D reaches a predetermined value, the signal check is ended (# 9, # 10).

The maximum time required for the soft processing from # 1 to # 4 is 40 uS, and the maximum time required for the soft processing from # 5 to # 9 is also 40 uS.
Furthermore, the time required for # 9 and # 10 software processing is 1
Since it takes 0 uS, one loop requires a maximum of 90 uS. Therefore, as in the first embodiment, this time is a constraint on the signal frequency that can be detected by the photo interrupter. That is, PIP1D and PI
In order not to miss the change of H and L of P2D, if A / D conversion is performed at least twice for each signal between H and H, a time of 2 × 90 uS = 180 uS is required. That is, in terms of the frequency of the photo interrupter, the maximum frequency of the photo interrupter reaches 8 kHz, whereas the PIP1D and PIP2D can follow only up to 1/180 uS = about 5.5 kHz.
The check of can not catch up.

In order to solve this, before the process of # 5, a process for determining whether it is a predetermined time is provided,
At a predetermined time, by skipping to # 1, only PIP1D is checked. As the predetermined time, as in the first embodiment, (1) PIP1D
Frequency exceeds 4 kHz, (2) after a lapse of a fixed time (T ₁ ) from the start of driving the focus motor 6, and after a lapse of a fixed time (T ₂ ) from the start of the drive stop operation of the focus motor 6, (3) focus It can be considered that after the constant pulse (P ₁ ) is counted from the start of driving the motor 6, the constant pulse (P ₂ ) is counted after the drive stop operation of the focus motor 6 is started.

Next, the operation principle of the two-phase photo interrupter 4 (or 5) will be described with reference to FIGS. FIG. 9A is a plan view of the blade 21 of the photo interrupter 4 for focusing, in which the protrusions are radially formed. FIG. 9B is a cross-sectional view of the photo interrupter 4, in which a light emitting diode (LE
D) 22 and a silicon photocell (SPC) 23 in the light receiving portion above the blade 21.

FIG. 10 (a) is a sectional view of the main part as seen from the side A shown in FIG. 9 (b). LED2 on the lower side of the blade 21
2 is one, the light receiving part on the upper side of the blade 21 is S
Two PCs 23a and 23b are provided, and their positional relationship is such that the phase difference between the pulse signals obtained from the two SPCs is 90 degrees as shown in FIG. 10 (b). For example, if the signal of SPC2 is deviated by 90 degrees in the right direction with respect to the signal of SPC1 in a certain driving direction as shown in FIG.
The signal 2 is shifted to the left with respect to the signal SPC1, and the microcomputer 2 (FIGS. 1 and 6) detects the driving direction of the lens by using this phase difference, Based on this, the counter 2a is automatically switched between up and down. In addition, as described above, 2
Since both the rising and falling edges of one pulse signal are all counted, the resolution can be quadrupled as compared with the conventional one in which only one edge of one pulse signal is counted.

Next, referring to FIG. 11, a concrete structure in which the above-mentioned drive control devices 1 and 1'are mounted on a so-called power focus or power zoom mechanism for continuously driving a movable lens of a camera by a motor will be described with reference to FIG. explain. FIG. 11 is a schematic view of the power focus mechanism. Motor 6
Is transmitted to the drive cam 35 via the gears 44, 43, 40, and the drive cam 35 and the rectilinear cam 37 move the shaft 38 of the lens 39 in the lens optical axis direction. The amount of movement is detected by A / D converting the signal output from the photo interrupter 4 provided coaxially with the gears 40 and 43 by the microcomputer 2 and counting the pulses. The count value and the lens position correspond to each other, and the focus position can be detected by adding or subtracting the count value based on the focus driving direction. Therefore, it suffices to output a control signal to the motor drive circuit 46 according to the count value to control the drive of the motor 6.

As described above, according to the drive control devices 1 and 1 ′ of this embodiment, depending on the two-phase A / D conversion method, the high frequency of which the signals of PIP1 to PIP4 of the photo interrupters 4 and 5 cannot be followed. Such as when
Since pulse detection is performed by switching to the single-phase A / D conversion method at a predetermined time, it becomes possible to perform pulse detection up to the same high frequency as when reading a single signal from the single-phase photo interrupter. The resolution of the movement direction of the driven member and the position detection of the driven member can be improved.

In the present embodiment, the two photodetectors of the zoom photointerrupter 5 are also arranged so that the output phase difference is about 90 degrees. In addition, in the present embodiment, since the zoom and the focus are not operated at the same time, one counter 2a is used for both purposes and the input is switched and used, but it is dedicated for each of the zoom and the focus. A counter may be provided.
Further, in the present embodiment, the example in which the drive control devices 1 and 1 ′ are applied to the camera is shown, but it goes without saying that the drive control devices 1 and 1 ′ can be applied to devices other than the camera.

[0027]

As described above, according to the drive control device of the first aspect of the present invention, it is possible to count both the first signal and the second signal detected by setting the movement of the driven member in different phases. Since the 1 count mode and the second count mode for counting one of the signals are switched at a predetermined timing to count the signals,
Single-phase signal output means while maintaining the merit that the resolution of the moving direction of the driven member and the position detection of the driven member can be improved when the phase signal output means is used. It is possible to count signals up to the same high frequency as when using.

[Brief description of drawings]

FIG. 1 is a circuit block diagram when a drive control device according to a first embodiment of the present invention is applied to a photographing optical system of a camera.

FIG. 2 is a diagram showing signal waveforms of PIP1 and PIP2 of a photo interrupter.

FIG. 3 is a diagram showing a PI when A / D converting PIP1.
It is a figure showing signs that P1 is sampled for every fixed time.

4A and 4B are diagrams showing a state in which PIP1 and PIP2 are sampled at regular intervals.

5A and 5B are diagrams showing changes in the frequency of the photointerrupter output signal when the focus motor is driven, and FIG. 5C is the focus motor drive time and the number of counts of the photointerrupter output signal. It is the figure which showed the relationship of.

FIG. 6 is a circuit block diagram of a drive control device according to a second embodiment of the present invention.

FIG. 7: PI converted into a digital signal by a waveform shaping circuit
It is the figure which showed the signal waveform of P1D and PIP2D.

FIG. 8 is a flowchart showing the flow of processing in the drive control device when checking digital signals of PIP1D and PIP2D.

FIG. 9A is a plan view of a photo interrupter blade in which protrusions are radially formed, and FIG. 9B is a cross-sectional view of the photo interrupter.

10 is a cross-sectional view of a main part of the photo interrupter viewed from the side A shown in FIG. 9 (b).

FIG. 11 is a specific configuration diagram of a focus mechanism for continuously driving a movable lens of a camera.

[Explanation of symbols]

 1, 1'Drive control device 2 Microcomputer 2a Counter 3 Motor driver 4 Photointerrupter 5 Photointerrupter 6 Focus motor 7 Zoom motor

Claims (1)

[Claims] 1. A drive control device for controlling the drive of a driven member, wherein a drive means for driving the driven member and a movement of the driven member driven by the drive means are detected, and the movement is detected according to the movement. And a second signal that detects a movement of the driven member in a phase different from that of the first signal output means and outputs a second signal according to the movement. Output means and A / D for A / D converting the first signal and the second signal
A converter, a first count mode for counting both the first signal and the second signal A / D converted by the A / D converter, and A / D converted by the A / D converter A second count mode for counting either the first signal or the second signal, the first count mode and the second count mode being set at a predetermined timing while the driven member is driving the driven member. 2. A drive control device comprising: a counting unit that switches between two count modes to count the first signal and the second signal.