JP2771874B2 - Moving distance detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a moving amount detecting device, and more specifically, a moving amount detecting device capable of accurately detecting a moving amount of a film by eliminating an erroneous signal output at an early stage of film winding. Related to the device.

[Prior Art] Power is supplied by a single power supply, for example, a battery, and a motor,
In a small system such as a camera including a magnet, a driver IC, an MPU (microprocessor unit), and the like, if a large power supply flows when the motor is started, the ground level of the entire system is fluctuated. Therefore, the output of an erroneous signal due to brush noise or the like during motor driving, the output of an erroneous signal from sensors or the like due to external or motor driving vibrations, and the like have conventionally been serious problems. However, the erroneous signal has a relatively short signal cycle as compared with a true signal (hereinafter, referred to as the present signal), and therefore, it is relatively easy to remove the erroneous signal.

However, the chattering signal output from the contact when the switch is turned on / off normally has a period of 1 msec.
Up to 5 msec, many of which are as long as 10 msec. on the other hand,
The noise that is output due to the external noise received by the sensor output is 1 μsec to 5 μsec due to static electricity, and the noise of the motor is 50 μsec.
It is as short as μsec to 200 μsec. Therefore, as a means for removing noise when taking in the sensor output, for example, a method has been used in which the stabilization is repeated periodically several times every 100 μsec to confirm that the output has been stabilized, and then taken in.

In addition, there are means using an RS flip-flop circuit and a single shot circuit, and means for sampling in synchronization with a clock signal. These measures are, for example, CQ
This is described in detail by Kunio Inokai, published by the publisher, "Design of Interface Circuits", etc., and will not be described here.

[Problems to be Solved by the Invention] The means described above are effective when the time ratio between the present signal and the erroneous signal is very large, but the erroneous signal does not greatly differ from the present signal in time. In this case, it is difficult to distinguish an erroneous signal from the present signal, so that no significant effect can be obtained. Now, taking the film winding as an example,
When receiving and controlling the film movement signal, insert an interface circuit that has hysteresis characteristics between the sensor that detects the movement of the film and the circuit that receives the signal and controls the actuators, so that it is resistant to noise. ing.

As shown in FIG. 7, when the sensor signal is within the range of the hysteresis width between the threshold value H and the threshold value L of the hysteresis characteristic of the circuit, the interface circuit is most vulnerable to disturbance and the output of the circuit is unstable. Become.
That is, if the sensor output is within the range of the hysteresis width of the interface circuit before the motor for winding the film is started, in addition to noise at the time of starting the motor, swing of the ground at the time of starting, etc. During the time from when the starting current is applied to when the film actually starts moving, an erroneous signal very similar to this signal is output even though the film is not moving.

Therefore, an object of the present invention is to solve the above-described problems, predict the time when an erroneous signal is output at the time of starting the motor, and do not take in the signal during that time, thereby controlling the movement of the film or the like. It is an object of the present invention to provide a movement amount detecting device which can be correctly performed.

[Means and Actions for Solving the Problems] A movement amount detection device according to a first embodiment of the present invention includes a pattern means that moves in accordance with the movement of a driven body, and the pattern that moves in accordance with the movement of the driven body Detecting means for detecting a change in the pattern, a timer means for measuring a predetermined delay time, and a counting means for counting a change in the pattern by the detecting means, and driving the driven body by driving a motor. In the movement amount detection device for detecting the movement amount, in response to the start of driving of the driven body, the predetermined time is started by the timer means, and the predetermined time is ended by the timer means. , The counting by the counting means is started.

A moving amount detecting device according to a second embodiment of the present invention is a moving amount detecting device that drives a driven body by driving a motor and detects the moving amount of the driven body. Pattern means that moves in accordance with the following, a detection means for detecting the pattern, a storage means for storing the output of the detection means before the movement of the driven body starts, a predetermined first delay time, and a first delay time. Delay time generating means for generating a second delay time longer than time, selecting means for selecting one of the first and second delay times based on an output of the storage means for driving the driven body, A counting means for counting the change of the pattern by the detecting means after the selected delay time.

According to the movement amount detecting device according to the first embodiment of the present invention, the counting operation of the detecting means is started after a lapse of a predetermined time from the start of driving the driven body by the motor.

Further, according to the movement amount detecting device according to the second embodiment of the present invention, prior to driving the motor, the output state of the detection means is stored and then the motor is started, and the motor is started based on the stored content. After the first or second predetermined time has elapsed, the counting operation of the detecting means is started.

Hereinafter, the present invention will be described in detail with reference to the drawings. This description is an example in which the amount of movement of the film when the film is driven by a motor is detected by a photo interrupter, but is widely applied to a movement amount detecting device including, for example, the movement amount of a moving member when a camera is driven by a lens. It is possible, and the detection may be performed by a photo reflector or the like.

FIG. 1 is a block diagram illustrating a basic configuration of a movement amount detecting device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of a film feeding mechanism of a camera, and FIG. ,
(B), (C), (C ') and (D) are diagrams showing output signals depending on the positional relationship of a photointerrupter (hereinafter abbreviated as PI) unit to a slit plate.

In FIG. 2, a film 59 pulled out from a film cartridge 53 is spread on an aperture window provided behind a photographic lens (not shown), and then wound on a film winding spool 55. Further, a slit plate 12 for detecting a moving amount of the film is fixed to an upper end portion of the sprocket shaft 57 in which sprocket wheels 57a, 57b provided corresponding to the perforation of the film 59 are fixed up and down, The number of slits due to the rotation of the slit plate 12 is determined by the photointerrupter unit 3.
Is detected, and this is output as a pulse signal.

The spool 55 is driven to rotate by the film winding motor 11. That is, the spool
An intermediate gear 63 meshes with a drive gear 62 fixed to the support shaft 55, and the gear 63 has a film winding motor.
11 output gear 64 to planetary gear mechanism clutch mechanism
The rotational driving force is transmitted via 65.
The sprocket shaft 57 is also driven by the motor 11 by a transmission mechanism (not shown).

On the other hand, the film 59 wound on the spool 55 is loaded into the cartridge by the film rewind motor 66 after the photographing is completed.
Automatically rewinds inside 53. That is, a fork member is provided on the film reel in the film cartridge 53.
68 is fitted to the drive gear 69 fixed to the member 68 from the output gear 71 of the film rewinding motor 66 via a clutch mechanism 67 by a planetary gear mechanism and a transmission gear 70. The rotational driving force is transmitted. The above is the outline of the film feeding mechanism.

The PI unit 3 for detecting the amount of movement of the film in the feeding mechanism configured as described above has, for example, a light emitting diode (hereinafter abbreviated as PLED) 4 as a light projecting unit on an upper end thereof and a lower end thereof. Phototransistors (hereinafter, abbreviated as PTR) 5 as light receiving units are disposed on the sides of the phototransistor, respectively. If there is no obstacle between the light emitting and receiving units, the PT
R5 receives the light beam from the PLED 4 and outputs an ON signal. On the other hand, if an obstacle is interposed between the light emitting and receiving units, the light beam from the PLED 4 is blocked and does not reach the light receiving surface of the PTR 5, so that the PTR 5 outputs an off signal. Therefore, the slit plate 12 in which the light-transmitting slits 12a and the light-shielding portions 12b are alternately arranged is interposed between the light emitting and receiving portions of the PI unit 3, and the slit plate 12 is rotated while corresponding to the movement of the film 59. For example, a signal that changes according to the film movement amount is obtained from the PTR5. If the PTR5 output signal is shaped by a waveform shaping circuit (not shown), a PIOUT signal having a short waveform corresponding to the film movement amount can be obtained.

However, when the PLED 4 and the winding motor 11 are energized in order to wind the film while detecting the amount of movement of the film, the PLED 4 emits light immediately, but the time lag until the motor 11 starts rotating and the transmission gears 62 to 65 immediately is not performed film feeding since such backlash, therefore, the slit plate 12 also does not rotate, it takes some time t _b until the slit plate 12 starts to rotate. During this time t _b, a slit plate 12
Is in the position where the previous film feed stopped, so PT
R5 will output the photocurrent in this state. This will be described below with reference to FIGS. 3 (A), (B), (C), (E) and (D).

3 (A), (B), (C), (E), and (D) show the photocurrent of PTR5 due to the positional relationship between the PI unit 3 and the slit plate 12 at the initial stage of winding, and the waveform of this photocurrent. FIG. 9 is a diagram illustrating a relationship with a PIOUT signal 14 obtained by shaping. In other words, the position of the PI unit 3 with respect to the slit plate 12 before the motor is started, the rotation direction, and the relationship between the output signal of the PTR 5 and the thresholds H and L are roughly divided into FIGS. 3 (A) to 3 (E). It is roughly divided into four types.

In each figure, the voltage waveform of PIOUT signal 14 and P
3 shows a current waveform of a TR5 output signal. In this current waveform, the mark 開始 indicates the start of lighting of the PLED4. Further, from emission PLED4, the time t _a the time until above the threshold H starts moving slit plate 12, the time t _b is the time until the slit plate 12 starts to move, the time t _c PIOUT
The time until the signal 14 rises for the first time is shown. And the bottom row is PI unit 3 before motor start.
3 shows a positional relationship between the slit plate 12 and the slit plate 12.

The type shown in FIG. 3A starts from a state where the PI unit 3 is shielded from light by the slit plate 12,
When ED4 is turned on, the signal output from PTR5 is below the threshold L level. After starting the motor 11, when the elapsed t _b times, the slit plate 12 starts to move in a counterclockwise direction, PI unit 3 is in a state to be translucent. Therefore, in the case of FIG. 3 (A), the time required to pass through the hysteretic width shown in the figure becomes very short while the slit plate 12 is rotating.
The influence of noise is relatively small.

In FIG. 3B, the PI unit 3 is positioned so as to straddle the light-transmitting slit 12a and the light-shielding portion 12b of the slit plate 12, and is output from the PTR 5 when the PLED 4 is turned on. The signal is between threshold L and threshold H. Therefore, when t _b time after starting the motor has elapsed, starts to move the slit plate 12, PI unit 3 is in a state where its entirety corresponds to the light transmitting slits 12a. Accordingly, in the type of FIG. 3 (B), for t _a time, PIOUT
Signal 14 is in a very unstable state. Therefore, even if the output signal of the PTR5 is slightly changed due to the swing of the ground level due to the large current at the time of starting the motor or the brush noise of the motor, the range of the thresholds H and L is exceeded.
A relatively wide pulse may be output to the PIOUT signal 14. This pulse is very similar to a movement signal output when the film is moved, unlike a mustache-like pulse due to noise or the like, and is difficult to recognize. Therefore, this section is represented as a danger zone.

In FIG. 3 (C), the PI unit 3 faces the light-transmitting slit 12a of the slit plate 12, and when the PLED 4 is turned on, the output signal of the PTR 5 is higher than the threshold H level. Then, when the time t _b elapses after the motor is started, the slit plate 12 starts to move, and the PI unit 3 changes from a light-transmitting state to a light-shielding state. Accordingly, in FIG. 3 (C), there may be a case as shown in FIG. 3 (E) in which the time of t _c is shorter than in the cases of FIGS. 3 (A) and 3 (B).

FIG. 3 (D) shows that the PI unit 3 straddles the light transmitting slit 12a and the light shielding part 12b of the slit plate 12,
When the PLED 4 is turned on, the output signal of the PTR 5 is between the threshold L and the threshold H. Then, when a time t _b elapses after the motor is started, the slit plate 12 starts to move, and the PI unit 3 is shielded from light. Thus, in the FIG. 3 (D), as in the case of FIG. 3 (B), for t _a time
The PIOUT signal 14 will have a very unstable danger zone. FIG. 3 (D) corresponds to FIG. 3 (A),
As in the case of (B), the time t _c is longer than that of FIG. 3 (C).

However, in the cases of FIGS. 3A, 3B, and 3D before the start of film winding, when the PLED 4 is turned on, the output signal of the PTR 5 rises from zero. And
Since the threshold H is not exceeded, the PIOUT signal 14 is always at "H" level. Similarly, in the case of FIG. 3 (C), when PLED4 is turned on, the output signal of PTR5 goes up from 0 and exceeds the threshold H.
The T signal 14 always goes to "L" level. Considering the time t _c , in the case of FIGS. 3 (A), (B) and (D),
After the slit plate 12 starts moving, it always passes through the threshold H and then falls below the threshold L, so that it is longer than in the case of FIG. 3 (C).

Therefore, the present invention provides a PI
Check the OUT signal, and if this PIOUT signal is at "L" level, after a short delay time (hereinafter referred to as a first delay time),
Start counting output. Also, the PIOUT signal is “H”
If it is at the level, the counting of the PI output is started after a long delay time (hereinafter, referred to as a second delay time). In other words, erroneous signals immediately after the winding motor 11 is energized are eliminated, and only this signal is
This is counted as a PIOUT signal, whereby the film movement amount is accurately obtained. This will be described below with reference to FIG.

FIG. 1 is a block diagram showing a case where the movement amount detecting device according to the present invention is applied to film feeding. In the figure, immediately after energizing a film moving means 103 such as a winding motor for driving a film, an output of a film movement detecting means 101 such as a photo interrupter is stored in a storage means 104 such as a latch circuit. If the output of the storage means 104 is at the "L" level, the first delay time of the delay time 107 is selected by the switching means 105, and the detection of the movement amount is suppressed by the control means 102 only during the first delay time. Also, storage means 1
If the output of 04 is "H" level, the switching means 105 selects a second delay time longer than the first delay time of the delay means 107,
The control means 102 suppresses the detection of the movement amount only during the second delay time. Thereafter, normal movement amount detection is performed, and the above is the basic principle of the present invention. An embodiment of the present invention having such a basic principle will be described with reference to FIGS.

FIG. 4 is a block diagram showing a case where a moving amount detecting device according to an embodiment of the present invention is applied to film feeding. In the figure, a control circuit 1 represented by an MPU sends an LED lighting signal 13 to a constant current circuit 2, a latch signal 15 to a latch circuit 7, and a first count start signal 16 to a delay circuit 8. And outputs a motor control signal 18 to the motor control circuit 10 and an overflow signal 17 from the counter 9.

When receiving the LED lighting signal 13 from the control circuit 1, the constant current circuit 2 supplies a constant current to the PLED 4 in the PI unit 3 to cause the PLED 4 to emit light. In addition, the PI unit 3
The PTR 5 controls the collector current input to the signal shaping circuit 6 based on the amount of light passing through the light-transmitting slit 12a of the reset plate 12 that rotates in conjunction with the hoist motor 11 driven by the motor control circuit 10. This signal shaping circuit 6 has a PT
The input current signal of R5 is converted into a current pulse shape signal with hysteresis characteristics, and then converted into a voltage / pulse shape signal by current / voltage conversion, and output as a PIOUT signal 14.

The rat circuit 7 stores and holds the PIOUT signal 14 at the rise of the latch signal 15 from the control circuit 1 and outputs the PIOUT signal 14 to the delay circuit 8. The delay circuit 8 has a short first time.
A delay time 20 and a long second delay time 21 are provided. When the output signal of the latch circuit 7 is at "L" level, the first delay time is provided, and when the output signal of the latch circuit 7 is at "H" level, the second delay time is provided. Select and switch each. Therefore, the delay circuit 8
Accordingly, the first count start signal 16 output from the control circuit 1 is delayed by the selected delay time and supplied to the counter 9 as the second count start signal 19. The counter 9 is a circuit that counts the number of pulses of the PIOUT signal 14. When the second count start signal 19 is turned on, the counter 9 starts counting the rising edge of the PIOUT signal 14, and is reset when the second count start signal 19 is turned off. . When the count value of the PIOUT signal 14 in the counter 9 reaches a predetermined number, the counter 9 outputs an overflow signal 17.

The motor control circuit 10 controls the motor 11 in four states: forward rotation, reverse rotation, short brake, and off by a motor control signal 18 output from the control circuit 1.
When the motor 11 rotates forward, the motor 11 drives a take-up spool 55 (see FIG. 2) around which the film is wound, and feeds the film. When the sprocket rotates with the feeding of the film, the slit plate 12 (see FIG. 2) fixed to the upper end of the sprocket shaft rotates.

FIG. 5 is a circuit diagram of a motor control circuit 10 (see FIG. 4) for controlling the rotation of the film winding motor 11, and includes two PNs.
P-type transistors Tr1 and Tr3 and two NPN-type transistors T
It is composed of a bridge circuit composed of r2 and Tr4, and two diodes D ₁ and D ₂ for transistor protection used when braking the motor.

Regarding the operation of the motor, as shown in Table 1 below,
By setting the input signal Q ₁ to “L” level and Q ₄ to “H” level, the transistors Tr 1 and Tr 4 are turned on, and the input signal Q ₂
To “L” level and Q ₃ to “H” level to set transistors Tr2 and T
It rotated forward by turning off the r3, similarly input signal Q ₁ to the "H" level, the Q ₄ "L" level, the input signal Q ₂ of the "H" level,
This is reversed by setting Q ₃ to the “L” level.

If braking by the "H" level of the input signal Q ₁ to Q _4, turning on the transistor Tr2, Tr4, Tr
1.Turn off Tr3 to short-circuit both ends of the motor, but if an overcurrent in the reverse direction flows through transistor Tr2 or Tr4,
Since these transistors may be destroyed, diodes D ₁ and D ₂ are connected in parallel to the transistors Tr ₂ and Tr 4 for protection.

FIG. 6 is a timing chart for winding up the film. In the figure, when the LED lighting signal 13 is turned on, the PLED 4 is turned on, and after the stabilization time has elapsed, the latch signal 15 is turned on from off, and the state of the PIOUT signal 14 is stored and held in the latch circuit 7. The motor 11 is rotated forward by the motor control signal 18, and immediately after that, the first count start signal 16 is turned on. On the other hand, the second count start signal
19 is the first if the output state of the latch circuit 7 is "L" level.
After the delay time, the second count start signal 19 is turned on after the second delay time if the signal is at “H” level. PIOU
The T signal 14 is a pulse output as the film moves, and when a predetermined number is counted by the count 9 (see FIG. 4), the overflow signal 17 is turned on.

When the overflow signal 17 turns on, the motor control signal
18 enters the show brake state. After the short brake is applied for a predetermined time, the motor control signal 18 is turned off, and the LED lighting signal 13, the latch signal 15, the first count start signal 16, the overflow signal 17, and the second count start signal 19 are all turned off. Becomes The motor current in the lowermost row in FIG. 6 represents a current waveform supplied to the motor 11.

FIG. 7 is a timing chart of the signal shaping circuit 6 shown in FIG. The signal shaping circuit 6 has two types of thresholds due to current, above and below the threshold H and the threshold L. Therefore, the current as curve l ₁ of Figure 7 in PTR5 by the rotation of the slit plate 12 flows,
The signal shaping circuit 6 sets the PIOUT signal 14 to the “L” level when the current of the PTR 5 is equal to or higher than the threshold H, and sets the PIOUT signal 14 to the “H” level when the current is lower than the threshold L, and outputs the signal. When the current of the PTR 5 is less than the threshold H and equal to or more than the threshold L, the signal shaping circuit 6 holds the immediately preceding state, gives a hysteresis characteristic due to the current, and outputs the current / voltage converted PIOUT signal 14.

The operation of this embodiment having such a configuration will be described below with reference to the flowchart of FIG. FIG. 8 is a processing flow of the MPU in the control circuit 1 in FIG. First,
When this flow starts, the process proceeds to step # 31,
The LED lighting signal 13 is turned on, and the PLED 4 is turned on. And
After the PLED 4 is turned on in step # 32 and the light amount is stabilized, the process waits for a predetermined time, and then proceeds to step # 33. In step # 33, the PIOUT signal 14 is stored and stored in the latch circuit 7. Then, when the operation proceeds to step # 34, the film winding motor 11 is rotated forward and the operation proceeds to step # 35. In step # 35, it is determined whether the stored PIOUT signal 14 is "H" or "L". If "H", the process proceeds to step # 37, and if "L", the process proceeds to step # 36. In step # 36, the first delay time is measured, and in step # 37, the second delay time is measured, and the flow advances to step # 38. The first and second delay times are based on the time ta in FIG.
For example, the first delay time is 5 msec and the second delay time is 30 mse
The c-position is set for each, but neither is set to exceed the time tc.

In step # 38, the second count start signal 19 is turned on, and the counter 9 starts counting the PIOUT signal 14. Then, in step # 39, the PIOUT signal 1
The process waits until the rising of step 4 is detected, and when the rising is detected, proceeds to step # 40. In this step # 40, since one pulse is detected, the number of pulses is increased by one. And
Proceeding to step # 41, the above steps # 39 to # 41 are repeatedly executed until the number of "pulse counted" pulses reaches a predetermined value corresponding to the movement of one frame of the film. Go to # 42. In this step # 42, the film is stopped by applying a short brake to the winding motor 11 for a predetermined time. And step # 43
Then, the short brake of the hoist motor 11 is released and the motor is turned off. Then, in step # 44, PLED4 is turned off,
In step # 45, the PIOUT signal stored in the latch circuit 7 is reset, and in step # 46, the pulse counter in the count 9 is stopped, and this flow ends.

[Effects of the Invention] As described above, according to the present invention, a malfunction of the film movement detecting means which can occur in the early stage of film movement by the film moving means is predicted, and the film movement detecting means is provided during the time when the malfunction will occur. By controlling so as not to take in the output of (1), a remarkable effect that a movement amount detecting device resistant to noise and other disturbances can be provided with a relatively simple circuit configuration and sequence configuration is exhibited.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the movement amount detecting apparatus according to the present invention applied to film feeding, FIG. 2 is an exploded perspective view of a film feeding mechanism of a camera, and FIG. FIG. 4 is a block diagram of an output signal according to a positional relationship with respect to a slit plate, and FIG. 4 is a block diagram of a case where a movement amount detection device according to an embodiment of the present invention is applied to film feeding; FIG. 6 is a circuit diagram of the motor control circuit in FIG. 4, FIG. 6 is a timing chart for winding one frame of the film, FIG. 7 is a timing chart of the signal shaping circuit in FIG. 4, and FIG. 5 is a flowchart illustrating an operation of the example. 1 ... control circuit 4 ... PLED (detection means) 5 ... PTR (〃) 7 ... latch circuit (storage means) 8 ... delay circuit (delay time generation means) 9 ... counter (counting means) 11 ... ... Hoisting motor (motor) 12 ... Slit plate (pattern means) 59 ... Film (driven body) 101 ... Film movement detection means (pattern means and detection means) 104 ... Storage means 105 ... Switching means (Selection means) 107 ... Delay means (Delay time generation means)

Claims (2)

(57) [Claims] 1. Pattern means for moving in accordance with movement of a driven body, detection means for detecting a change in the pattern accompanying movement of the driven body, timer means for counting a predetermined delay time, And a counting means for counting a change in the pattern by the detecting means. The moving amount detecting device for driving the driven body by driving a motor and detecting the moving amount, comprising: In response to the above, the predetermined time measurement is started by the timer means, and the counting by the counting means is started after the predetermined time measurement by the timer means is completed. apparatus. 2. A movement amount detection device for driving a driven body by driving a motor and detecting a movement amount of the driven body, comprising: a pattern means for moving in accordance with the movement of the driven body; Detecting means for detecting; a storage means for storing an output of the detecting means before the movement of the driven body is started; a predetermined first delay time; and a second delay time longer than the first delay time.
Delay time generating means for generating a delay time; selecting means for selecting one of the first and second delay times based on an output of the storage means for driving the driven body; And a counting means for counting the change of the pattern by the detecting means after a lapse of time.