JPH0743771A - Control device for quantity of transmitted light - Google Patents

Abstract

PURPOSE:To optimally control quantity of transmitted light (optimum exposure) by controlling quantity of opening in accordance with a present running speed of a shading blade when ambient temperature is varied or when an aged deterioration is found. CONSTITUTION:A preliminary running time detecting circuit 8 to which a signal is inputted calculates a preliminary running time of a shading blade from the number of pulses per unit time, a discriminating circuit 10 discriminates whether an output of the circuit 8 is included within a range between the upper limit value and the lower limit value of a preliminary running time threshold value previously set in a threshold value setting device 9 or not. And when the output value of the circuit 8 is not included between the upper limit and the lower limit of the threshold value, an output signal is issued for a main control circuit 11, the main control circuit 11 rewrites a control table previously stored in a storage means 12 in accordance with its input signal when a signal from the circuit 10 is inputted. After that, a driving signal for a driving circuit 7 is varied so as to drive the shading blade 3 in accordance with the control table rewritten in these way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light transmission amount control device such as a shutter device also used as an aperture for an optical device such as a lens shutter camera, and more particularly to a blade member for changing a light transmission opening of the device. The present invention relates to a light transmission amount control device of a type in which an electromagnetic actuator such as a stepping motor is driven.

[0002]

2. Description of the Related Art Conventionally, in a light transmission amount control device such as an aperture / shutter device mounted in an optical device such as a lens shutter camera, a blade member for changing a light transmission opening is intermittently provided in a stepping motor or the like. It is driven by a rotary electromagnetic actuator, and the instantaneous position of the blade member during traveling is detected as a pulse signal by a non-contact type detector such as a photo interrupter fixed in the device, and the transmission value of the device is detected from this detected value. Detects the instantaneous value of the aperture for light and controls the energization time to the coil of the electromagnetic actuator so that the aperture is adjusted according to the detected value of the field brightness obtained from the photometric device mounted on the camera. The position and the movement amount of the blade member are controlled by controlling the circuit.

Further, in the above-mentioned light transmission amount control device,
When the ambient temperature exceeds a certain value, the control table stored in advance in the control circuit (that is, the relationship between the energization time to the coil of the electromagnetic actuator and the opening amount based on the photometric value is stored in advance). The control data table) is uniformly corrected irrespective of the characteristics of each light transmission amount control device and the traveling speed of the blade member of each device.

[0004]

In the above-mentioned conventional light transmission amount control device, when the ambient temperature changes, the control table stored in the control circuit causes the traveling speed of the blade member of each light transmission amount control device. (This is slightly different for each light transmission amount control device.) Since it is uniformly corrected regardless of the unique characteristics, when the ambient temperature exceeds a predetermined value, each light transmission amount control device. In some cases, the operation characteristics of (3) also change, and as a result, the optimum exposure operation (that is, the optimum light amount control corresponding to the photometric value) cannot be performed.

Further, when the number of times of use and the years of use of the device overlap, the traveling speed of the blade member changes due to secular change due to wear of mechanical parts and adhesion of dust etc. However, since the control function for correcting the opening amount and the like according to the change in the traveling speed of the blade member due to such a cause is not mounted, there is a problem that the optimum exposure is not performed even when the device is aged. .

An object of the present invention is to provide a novel light transmission amount control device which solves the problems inherent in the conventional light transmission amount control device described above.

[0007]

When the traveling speed of the vane member changes from the time when the device is newly manufactured, control must be performed according to the traveling speed of the vane member at the present time. For that purpose, a detecting means for constantly detecting the traveling speed of the blade member is required.

By the way, in the conventional light transmission control device, the period from the start of driving of the blade member in the fully closed state of the device to the actual formation of the aperture is referred to as a preliminary traveling period or a run-up period. In this period, the vane member has already been driven, but the translucent opening of the device has not been formed yet. However, since the moving amount and moving speed of the blade can be detected by the photo interrupter, the running speed of the blade member during the preliminary running period is detected, and the detection result is used to measure the opening amount of the device. The above problems can be solved by performing control. In the conventional device, the movement of the blade member during the run-up period of the blade member is detected by a detector such as the photo interrupter in order to detect the time when the running of the blade member ends. Running time during the run-up period (preliminary running time)
And the running speed were not detected.

In the present invention, the output signal of the detector is used to detect the traveling time of the blade member during the run-up period (preliminary traveling period), and when this traveling time is not within the predetermined range, Corrects the control table in the control circuit according to the traveling time detection value.

[0010]

As described above, in the light transmission control device of the present invention, the change in the traveling speed of the blade member at the present time is detected by detecting the traveling time of the blade member during the preliminary traveling period. Since the control table in the control circuit is corrected according to the running time, even if the running speed of the vane member is changed due to aging or the like compared to when the device was newly manufactured, it is always good. The light transmission amount control device can be operated.

[0011]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a front view of a mechanical main structural portion of the light transmission amount control device of this embodiment. In the figure, 1 is a base plate having a circular light-transmitting hole formed through the center thereof, and 2 and 3 are pivotally attached to the base plate 1 by pins 1a and 1b projecting from the front surface of the base plate 1. Shield blades 5 which are rotated around 1a and 1b are fixed to the rear surface of the base plate 1 and have stepping means for driving the shield blades having an output axis parallel to the axis of the base plate 1 (that is, the optical axis of the optical system). An electromagnetic actuator 6 such as a motor is a photo interrupter fixed to the base plate 1 to detect slits 3b penetrating the tip of the blade 3 in a row. In FIG. The hole (that is, the light-transmitting opening) is completely shielded by both light-shielding blades.

Slotted holes 2a and 3a (the slotted hole 3a is hidden behind the blade 2 in FIG. 4) are provided in the vicinity of the pin holes into which the pins 1a and 1b are inserted in the two light shielding blades 2 and 3. A projecting pin 4 of a drive ring (not shown) is inserted through the elongated holes 2a and 3a so as to be relatively slidable. The drive ring is supported by the main plate 1 so as to be rotatable around the central axis of the main plate 1, and an eccentric fixed to the output shaft of the electromagnetic actuator is provided in an elongated hole (not shown) formed through the ring. A pin (not shown) is slidably inserted. Therefore,
When the output shaft of the electromagnetic actuator 5 is rotated, the ring is rotated about the axis of the main plate 1, and the pin 4 projecting on the ring moves substantially vertically in FIG. The light-blocking blades 2 and 3 are rotated about the respective pivot pins 1a and 1b in opposite directions,
As a result, the central hole (that is, the translucent opening) of the main plate 1 is opened and closed. Further, the instantaneous position and movement amount of the light-shielding blade 3 at that time are detected by the photo interrupter 6 as a detection pulse of the slit 3b, and the instantaneous aperture amount in the device is detected from the count value of the pulse signal, and the aperture amount is also detected. The drive control of the electromagnetic actuator is performed so that is a value corresponding to the photometric value.

The structure of the mechanical structure of the above-mentioned light transmission control device is the same in the device of this embodiment and the conventional device, and the structure of the electromagnetic actuator 5 is also the same as that of the conventional device. Therefore, further detailed description will be omitted.

Next, with reference to FIG. 1, a description will be given of the characteristic structure, function, operation and the like of the light transmission amount control device of the present invention.

In FIG. 1, reference numeral 3 denotes the above-mentioned light-shielding blade, and the blade 3 is adapted to rotate around the projecting pin 1b of the main plate 1. Reference numeral 3a is an elongated hole penetrating the blade 3, and the pin 4 of the drive ring (not shown) described above is inserted into the elongated hole so as to be relatively slidable. Reference numeral 5 is the electromagnetic actuator described above. The actuator 5 includes a rotor 5b made of a permanent magnet having a central axis 5a, and a rotor 5b.
It has a pair of stator yokes 5c and 5d arranged to face the outer peripheral surface of b, and coils 5e and 5f fitted to each of the stator yokes, and the shaft 5a has a circle (not shown). The plate is fixed, and an eccentric pin protruding from the disc is inserted into an elongated hole of a drive ring (not shown) so as to be slidable relative to each other. Then, the protruding pin 4 of the ring is attached to the elongated hole 3 of the blade 3.
It is slidably inserted in a.

Reference numeral 7 is an actuator drive circuit for controlling the energization of the coils 5e and 5f of the actuator 5.
Reference numeral 11 denotes a main controller for controlling the drive circuit 7 to control the drive amount of the blades 2 and 3 and the aperture amount of the light transmission aperture.
Reference numeral 2 is control data in the light transmission amount control device (control data such as a drive amount of the blade, a traveling speed, and a relationship with a photometric value)
A storage means such as an EEPROM for storing
Reference numeral 4 denotes a known photometric device which is mounted on an optical device such as a camera together with the light transmission amount control device of this embodiment. Reference numeral 6 denotes the above-mentioned photo interrupter, which is a detection means for detecting the slit 3b penetrating the tip of the blade 3, and has a light projecting element 6a and a light receiving element 6b. Reference numeral 8 denotes a preliminary traveling time detection circuit for detecting the preliminary traveling time of the blades 2 and 3 (that is, the traveling speed of the blade) by counting the pulse signals generated from the light receiving element 6b.
Is a threshold value setting device for setting a threshold value for preliminary travel time, 1
0 compares the preliminary traveling time detected by the preliminary traveling time detecting circuit 8 with the threshold value set by the setting device 9 and generates an output signal corresponding to the difference between the threshold value and the detected value. The determination circuit. The preliminary traveling time detection circuit 8, the threshold value setting device 9, the determination circuit 10, the main control circuit 11, the storage means 12, and the like may be configured inside the microcomputer. Further, the main control circuit 11 may be composed of a microprocessor having an arithmetic function, and the circuit 11, the threshold value setting device 9, and the storage means 12 may be controlled by the circuit 11.

Reference numeral 13 is a position detector for detecting the instantaneous position of the light-shielding blades 2 and 3 after the driving of the light-shielding blades 2 and 3 is started. The detector 13 is also configured as a counter, and is a conventional device. Is also provided. The output signal of the detector 13 is not a signal for the follow-up control of the blade, but a signal for detecting whether or not the blade has reached the opening start position.
The amount of electricity supplied to the coil is not changed.

Next, the operation and function of the light transmission control device of the present invention having the configuration of FIG. 1 will be described.

S101 for detecting whether or not a release switch mounted on an optical device such as a camera is turned on,
When the photometric value S102 detected by the photometric device 14 is input to the main control circuit 11, the main control circuit 11 determines the aperture amount according to the photometric value S103, and the drive amount corresponds to the aperture amount. Thus, the drive signal is output to the drive circuit 7. The drive circuit 7 energizes the coils 5e and 5f of the electromagnetic actuator 5 according to the signal S10.
5, the rotor 5b is rotated by the electromagnetic force of the magnetic field generated by the current flowing through the coil, and as a result, the projecting pin 4 of the drive ring (not shown) is moved in the direction of the arrow shown in the drawing, and the light shielding blades 3 and 2 are rotated about their respective rotation centers. FIG. 4 focusing on 1b and 1a
Is rotated from the position. When the light-shielding blades 2 and 3 are rotated from the position shown in FIG. 4 and the light-transmitting opening of the light-transmitting amount control device is gradually opened, the opening is still formed during the initial opening operation of the blade. However, the opening remains in the fully closed state for a while, that is, the light shielding blade is in the preliminary traveling (running) state. When the light-shielding blade 3 starts to move from the position of FIG. 4, the slit 3b starts moving between the light projecting element 6a and the light receiving element 6b of the photo interrupter 6, so that a pulse signal is generated from the light receiving element 6b in S105 and S106. It is determined whether or not the pulse signal detected in S105 has an abnormality, and if there is an abnormality, the process proceeds to S108. The malfunction is canceled in S109, and the process proceeds to S101 again. The preliminary traveling time detection circuit 8 to which the signal is input calculates the preliminary traveling time of the blade from the number of pulses per unit time, and the preliminary traveling time calculated by the circuit 8 is input to the determination circuit 10. Judgment circuit 1
At 0, it is determined whether or not the output of the circuit 8 falls within the range between the upper limit value and the lower limit value of the preliminary travel time threshold value set in advance by the threshold value setting device S101, S1.
12. When the output value of the circuit 8 does not fall between the upper limit and the lower limit of the threshold value, an output signal is issued to the main control circuit 11, and the main control circuit 11 outputs the output signal from the circuit 10. When a signal is input, the control table stored in the storage unit 12 in advance is input according to the input signal (that is,
S101, S113 for rewriting the control table (in accordance with the difference between the preliminary traveling time detected by the circuit 8 and the upper limit value and the lower limit value of the threshold value set in the setting device 9) According to the rewritten control table S11 for changing the drive signal for the drive circuit 7 so as to drive the blades
4. Therefore, the coils 5e and 5 of the electromagnetic actuator 5 are
The energization time for f is changed from the initial value. In this way, after the light-shielding blade is driven for the energization time corrected from the energization time at the beginning of driving, the opening of the light transmission amount control device starts to open.

FIG. 2 shows a flowchart of the control operation performed by the main control circuit 11.

FIG. 3 shows the output signal of the photo interrupter 6, the rotation angle of the light shielding blade, the opening amount, and the opening characteristic. In FIG. 3, the abscissa axis represents time and the light-shielding blade rotation angle, the ordinate axis represents the opening amount, and the curves A, B, and C represent the differences in the opening characteristics due to the differences in the traveling speed of the blades. That is, when the traveling speed of the blade is high, the preliminary traveling time is short, the opening characteristic is represented by A, and the control time from when the opening is formed to when the predetermined opening amount is reached is short. The opening characteristic changes to B and C as the traveling speed of the blade decreases. In this figure, from the start of the traveling of the blade to the second output pulse of the photo interrupter 6 is the preliminary traveling period (running period) of the blade, and the opening of the third output pulse of the photo interrupter 6 is started. Next to
The pulse count for the drive control of the blades (drive control of the electromagnetic actuator) is started. As described above, in the light transmission amount control device of the present invention, when the speed of the blade is slower than that at the time of new manufacture of the device due to aging, etc., and the aperture characteristic is, for example, C, Since the drive control of the electromagnetic actuator 5 is automatically changed according to the change of the traveling speed of the blade by the control such as the above, even if the traveling speed of the blade is changed, the opening characteristic of the device is a new product of the device. It will be kept in its original condition. Therefore, even when the ambient temperature is changed or the traveling speed of the blade is decreased due to aging, the light transmission amount control device of the present invention can always perform the optimum light amount control, that is, the optimum exposure control. it can.

The decision circuit 10 shown in the above embodiment may be constituted by a well-known window type comparator, but may be constituted by a differential amplifier. Also,
Since both the preliminary traveling time detection circuit 8 and the instantaneous position detector 13 are counter circuits, they may be shared.

[0024]

As described above, in the light transmission amount control device of the present invention, the aperture amount control according to the current traveling speed of the light shielding blade is performed even when the ambient temperature changes or changes over time. As described above, the optimum light transmission amount control (that is, the optimum exposure control) can always be performed, and the reliability of the optical device equipped with the apparatus can be significantly increased.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a main configuration of a light transmission amount control device of the present invention.

FIG. 2 is a flowchart showing the operation of the apparatus shown in FIG.

FIG. 3 is a diagram for explaining the operation and function of the apparatus.

FIG. 4 is a schematic view for explaining a main part of a mechanical structure of the device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Base plate of translucency control device 2, 3 ... Shading blade 4 ... Pin (not shown) of drive ring 5 ... Electromagnetic actuator 5a ... Shaft 5b ... Rotor 5c, 5d ... Stator yoke 5e, 5f ... Coil 6 ... Photo Interrupter 7 ... Drive circuit 8 ... Preliminary traveling time detection circuit 9 ... Threshold value setting device 10 ... Judgment circuit 11 ... Main control circuit 12 ... Storage means 13 ... Instantaneous position detector 14 ... Photometric device

Claims (1)

[Claims] 1. A light transmission amount control device of a type in which a light-shielding blade is driven by a drive source such as an actuator and the light-shielding blade is preliminarily traveled before the opening of the light-transmissive opening is started. The preliminary traveling time detecting means for detecting the traveling time of the light-shielding blade, the threshold setting means for setting thresholds such as the upper limit value and the lower limit value of the preliminary traveling time, and the preliminary traveling time detecting means. Determining means for determining whether or not the detected preliminary traveling time falls within the range of the threshold value set by the threshold value setting means; and drive control of the drive source according to the output of the determining means. And a drive source control means for changing the light transmission amount control device.