JPH01289924A - Electromagnetic shutter - Google Patents

Abstract

PURPOSE:To enable fast, high-accuracy exposure control by providing a constant voltage circuit which selects and sets plural output voltages in consideration of ambient temperature, frictional force, etc., and selecting those voltages according to the movement state of shutter blades. CONSTITUTION:An opening coil 13 and a closing coil 15 which drive the shutter blades are supplied properly with plural specific voltages in consideration of the ambient temperature from the constant circuit 1 and the frictional force based upon the structure of the shutter blades themselves in response to the operation of a photointerrupter device 6, and consequently electromagnetic forces generated by both coils 13 and 14 are controlled according to the ambient temperature or the operation state, etc., of the shutter blades themselves. Further, clocking operation in the driving operation period of the shutter blades is started on detecting the movement state of the shutter blades themselves, so the clocking operation in said period is performed without reference to variance in stationary frictional force among the shutter blades. Consequently, the fast shutter which has high exposure accuracy is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electromagnetic shutter in which a shutter blade is opened and closed by an electromagnetic driving force generated in a coil placed in a magnetic field by passing a current through the coil. It is.

BACKGROUND OF THE INVENTION In the electromagnetic shutter of the above-mentioned type, if the shutter drive source is to be downsized in consideration of housing in the camera, the coil constituting the drive source must also be downsized. However, when the coil is made smaller, the resulting electromagnetic driving force becomes smaller (as a result, the operation of the shutter blades is greatly affected by frictional force, which causes variations in the aperture characteristics of the shutter blades, resulting in exposure errors. There was a risk that this would occur.

In order to solve these problems with conventional electromagnetic shutters, for example, the voltage of the battery is boosted by a booster circuit to charge a capacitor, and when the shutter blades are closed, a large drive current is generated by discharging the accumulated charge in the capacitor. Proposals have been made to improve exposure accuracy by making the shutter closing characteristics steeper by obtaining
Publication No. 2268).

Problems to be Solved by the Invention The above-mentioned electromagnetic shutter has the advantage that a charging mechanism for generating a mechanical driving force is not required, and that the mechanism for controlling exposure can be entirely replaced with an electronic circuit.

However, when trying to improve exposure accuracy and speed up shutter operation, it has become clear that the following problems arise when considering the driving operation characteristics of the shutter blades.

Looking at the driving operation characteristics of the shutter blades in an electromagnetic shutter, as shown in FIG. 3, at time T. When the shutter blade opening signal is supplied at , the shutter blade starts opening at time T1 after a period TA has elapsed, and reaches the fully open state at time T2.

Then, when the close signal is supplied at time T3, the period T begins.

It starts to close at time T4 after the elapse of time, and reaches a completely closed state at time T5.

Note that periods TB and T in FIG. 3 indicate periods during which the shutter blades are actually moving to open or close, respectively.

As is clear from FIG. 3, this type of electromagnetic shutter always has periods TA, TB, To, and T. Therefore, in order to improve exposure accuracy and speed up shutter operation, each of the above periods is required. The period must be managed appropriately.

For example, in order to realize a high-speed shutter, (1) the shutter blades are opened steeply, that is, the slope of the characteristics within the period TB is made steep, and this period T4 is therefore shortened; (2)
The shutter blade is closed steeply, that is, the slope of the characteristic within the period T is made steep.

(3) Shutter blade open signal or close -
3= It is desired that the response characteristic from the output of the signal to when the circuit actually starts to open or close is fast, that is, the periods TA and To are short.

Note that the above-mentioned proposal proposes that the electromagnetic driving force to be supplied to the shutter blade during the closing operation be increased during the period T.

, 1゛, is clearly an attempt to shorten it.

Now, if we look at each of the periods TA-T in more detail, the periods T[l, 'I'o are the periods during which the shutter blades are actually moving, and needless to say they vary depending on the set exposure time. It is conceivable that this may vary depending on the magnitude of the electromagnetic driving force for opening or opening supplied to the shutter blades and the frictional force of each electromagnetic shutter.

On the other hand, the periods TA and To may vary under the influence of frictional force, the magnitude of the supplied electromagnetic driving force, or inertial force, as in the case described above.

Note that it has been confirmed that the magnitude of the frictional force changes depending on the temperature around the device.

As a result, it is clear that in order to appropriately manage each of the periods TA to T as described above, the magnitude of the electromagnetic driving force by the coil must be controlled with consideration to frictional force and the like. In other words, if we only consider speeding up the shutter operation, it is sufficient to set the electromagnetic driving force supplied to the shutter blades to a size that is not affected by the above-mentioned frictional force. , can be shortened, and speeding up can be achieved. However, in this case, as the drive source such as a coil becomes larger, the influence of the inertia of the shutter blade becomes greater. A problem arises in that the lengths of the periods T.) are different, making it impossible to perform highly accurate exposure control operations. Therefore, in order to achieve high exposure accuracy, the magnitude of the electromagnetic driving force described above must be set in consideration of the balance with frictional force and the like.

In addition, in the proposed device mentioned above, during the opening operation, a constant current is supplied to the coil by a constant current circuit to set a predetermined electromagnetic driving force, and during the closing operation, a large electromagnetic driving force is set by the accumulated charge of the capacitor. has been done. However, consideration has been given to the frictional force and ambient temperature mentioned above. For example, if the magnitude of the frictional force varies due to fluctuations in the ambient temperature, the driving characteristics of the shutter blade will also vary, making it difficult to achieve high-precision exposure. It is conceivable that the problem of inability to perform control may occur, and there is still room for improvement.

The present invention has been made to solve the above-mentioned problems, and is an electromagnetic shutter of a type in which a shutter blade is driven by an electromagnetic driving force generated in a coil, in which the electromagnetic driving force supplied to the shutter blade has at least a friction The purpose of the present invention is to provide an electromagnetic shutter that is controlled to have a driving force suitable for achieving high exposure accuracy and high-speed shutter taking into consideration factors such as force and ambient temperature.

Means for Solving the Problems The electromagnetic shutter according to the present invention sets the power supply voltage supplied to the coil to a plurality of predetermined voltages that take into account at least the frictional force and the surrounding temperature, and selects one of them to apply the voltage between the output terminals. a first series body consisting of a first switch element and an opening coil, which are each independently connected between their output terminals, and a second series body consisting of a second switch element and an opening coil. body and the driving state of the shutter blades, and when a state corresponding to the start of opening is detected,
A photointerrupter device outputs a detection signal, sets a shutter blade drive period in response to subject brightness and film sensitivity, outputs a shutter blade open signal in response to shutter release, and also outputs a shutter blade open signal in response to shutter release. When the detection signal is supplied, timing operation for the driving operation period is started, and a control signal for appropriately selecting the output voltage of the constant voltage circuit is output, and at the end of the timing operation, an open signal and a control signal are output. and shutter opening/closing control means for stopping and outputting a shutter blade closing signal.

Function Since the electromagnetic shutter according to the present invention is configured as described above, the opening coil and the opening coil for driving the shutter blade are subject to frictional forces based on the ambient temperature and the structure of the shutter blade itself. A plurality of predetermined voltages are appropriately supplied in response to the operation of the photointerrupter device, and as a result, the electromagnetic driving force generated in both coils is controlled according to the ambient temperature or the operating state of the shutter blade itself. be done.

In addition, since the timing operation for the driving operation period of the shutter blade is started by detecting the moving state of the shutter blade itself,
Regardless of the variation in static friction between the sides of the shutter blades,
A timekeeping operation for the period described above is performed.

Embodiment FIG. 1 is an electrical circuit diagram of an embodiment of an electromagnetic shutter according to the present invention.

As is clear from the figure, the constant voltage circuit 1 is connected to the power supply terminal E. This constant voltage circuit 1 includes a transistor T
r, + T r2, a constant current circuit 2 consisting of resistors R,, R,, an LED 3, an appropriate number of Schottky diodes 4, transistors Tr3 to Tr7, and resistors R3 to R10.
and a variable resistor R11, as described later.
A second predetermined voltage V, , V2 is output.

In addition, a relay release switch 5, which is turned on when the shutter release operation is performed, is connected to the power supply terminal E.
The transistor Tr8 and the resistor R act as a control switch to operate the constant voltage circuit 1 when the voltage is turned on.
12, R+3 are also connected.

Furthermore, the power supply terminal E is also connected to a photointerrupter device 6 via a relay switch 5. This photointerrupter device 6 includes an LED 7, a light receiving element 8,
C-MOS inverter 9, resistor RI4. R+5, L
A shutter blade (
(not shown) and a light control member 10, which is a pair of slits formed in the shutter blade itself, for controlling the incident state of light from the LED 7 to the light receiving element 8. has been done.

1st. First and second series bodies 12 and 14 are connected in parallel between the output terminals 1a and 1b of the constant voltage circuit 1 to which the second predetermined voltage is appropriately selected and output. First series body 1
2 is composed of a capacitor 11, a transistor Tr9 which is a first switching element, an opening coil 13 which generates an electromagnetic driving force for opening the shutter blade when energized, and a resistor R16. The body 12 is composed of a transistor T r Ho which is a second switching element, an opening coil 15 and a resistor R1□ which generate an electromagnetic driving force that closes the shutter blade when energized. As is clear from the figure, transistors Tr9.
Tr, o and the transistor Tr7 of the constant voltage circuit 1,
Output terminals 17a and 17 of the shutter drive circuit 17, respectively.
The respective operating states are controlled by the open signal, the close signal, and the control signal output from the terminals b and 17c.

This shutter drive circuit 17 outputs an open signal from its output terminal 17a when the release switch 5 is turned on, and a film sensitivity detection circuit that detects brightness information from a photometry circuit 18 that measures subject brightness and the sensitivity of the film used. Based on the film sensitivity information from 19, the driving operation period of the shutter blade is set. Furthermore, upon receiving the output signal from the photointerrupter device 6, it starts measuring the operating period, and outputs a control signal for varying the predetermined voltage value output by the constant voltage circuit 1 from its output terminal 17c, and measures the time. At the end of the process, the output of the open signal and the control signal is stopped, and at the same time, a close signal is output from the other output terminal 17b.

That is, the shutter drive circuit 17, together with the above-described photometry circuit 18 and film sensitivity detection circuit 19, constitutes a shutter opening/closing control means 16 that controls the opening and closing operations of the shutter blades.

The operation of this embodiment will be described below with reference to the signal waveform diagram in FIG. 2 and the driving operation characteristics of the shutter blades shown in FIG. 3.

Now, time T shown in FIG. When the shutter release operation is performed at step 2, the release switch 5 is turned on, which turns on the transistor Tr8, and the constant voltage circuit 1 is brought into operation. Also, Tsume.

The LED 7 of the interrupter device 6 lights up, and the light control member 10 becomes ready for movement detection. Furthermore, as shown in FIG. 2(a), the shutter drive circuit 17 outputs an open signal for opening the shutter blade from its output terminal 17a, and supplies it to the transistor Tr9. Note that at this time, the output states at the other output terminals 17b and 17c of the drive circuit 17 are respectively transistor T r +
Needless to say, o + T r 7 is not turned on.

In this way, when the transistor Tr7 is in the off state, the constant voltage circuit 1 connects the resistor R7 between the output terminals 1a and 1b.
and variable resistor R11, and further outputs a first predetermined voltage V1 that is set in consideration of ambient temperature, frictional force, and the like.

That is, as is clear from the figure, the constant voltage circuit 1 has the following characteristics.
The voltage between both terminals of the resistor R6 is made constant by the constant current circuit 2, the LED 3, and the like. And transistor Tr7
is off, the voltage between output terminals 1a and 1b is applied to resistor R6, variable resistor RI+, and transistor Tr.
It is returned via 6.

Therefore, the voltage between the output terminals 1a and 1b is divided by the resistor R7 and the variable resistor R1+, and the transistor T
The operation of r6 is controlled to control the voltage across both terminals of resistor R6. Therefore, the operation of the transistor Tr5 connected to this resistor R6 is controlled.

As a result, the operation of the transistors T r31 T r4 is controlled, and the voltage between the output terminals 1a and 1b becomes the first predetermined voltage V! controlled by the division ratio of the resistor R7 and the variable resistor RI+! This means that it will be set to .

In addition, since the LED 3, Schottky diode 4, etc. having a predetermined temperature coefficient are provided in the circuit for constantizing the voltage between both terminals of the resistor R6, the resistor R6
The voltage across it changes with temperature. Therefore, the first predetermined voltage between the output terminals 1a and 1b changes in accordance with the ambient temperature.

Furthermore, by appropriately selecting the number of LEDs 3 and the like having a temperature coefficient, the temperature characteristics at both ends of the resistor R6 can be appropriately controlled.

For this reason, for example, if the number of elements such as LED3 is determined by considering the influence of the frictional force of the electromagnetic shutter mechanism, that is, by considering that the frictional force tends to decrease as the temperature increases, the resistance R6 The temperature characteristics of the voltage between both terminals are
By making the voltage fluctuation rate smaller than when considering only the influence of temperature, it becomes possible to cope with frictional force that varies depending on temperature. In this embodiment as well, the above considerations are taken.

Since the transistor Tr9 is supplied with an open signal from the shutter drive circuit 17, it is turned on, and when the constant voltage circuit 1 outputs the first predetermined voltage, it is as shown in FIG.
As shown in b), time T. 2 to the opening coil 13. Then, the opening coil 13 generates an electromagnetic driving force for opening the shutter blade, and supplies it to the shutter blade.

The shutter blade begins to move after the electromagnetic driving force from the opening coil 13 overcomes the static friction force of the shutter blade, and as shown in FIG. 2, the shutter blade begins to move at a time TI2 corresponding to the time T1 explained in FIG. Begin to form more exposed openings.

When the shutter blade moves, the light control member 1o also moves in conjunction with the movement, so the opening operation of the shutter blade is detected by the photointerrupter device 6.

This photointerrupter device 6 outputs a detection signal as shown in FIG. supply

Note that the operation of determining the time TI2 of the photointerrupter device 6 is basically a light emitting/receiving operation by the LED 7 and the light receiving element 8 via the light control member 1°. Normally, when the luminance of light emitted by the light receiving element 8 changes, the light receiving state of the light receiving element 8 changes, making it impossible to accurately determine the time point TI2. However, in this embodiment, the light receiving output of the light receiving element 8 is changed to Since the detection is carried out through the power supply voltage, it is possible to absorb fluctuations in the power supply voltage, that is, the operating level of the inverter 9 changes in response to fluctuations in the power supply voltage, and therefore the time-point determination operation is always based on accurate light emitting and receiving operations. We can expect this.

Now, when the shutter drive circuit 17 is supplied with a detection signal from the photointerrupter device 6 as described above, the shutter drive circuit 17 receives object brightness information from the photometry circuit 18 and sensitivity information from the film sensitivity detection circuit 19 in response to the shutter release, for example. Based on this, the timing operation for the preset shutter blade drive period T is started from time TI2, as shown in FIG. 2 ω). At the same time, time T. At 2,
The output level of the output terminal 17c is inverted from the off state to the on state of the transistor Tr7, as shown in FIG. 2(e).

When the transistor Tr7 is turned on, the resistor R8 becomes the resistor R7.
are connected in parallel to the output terminals 1a-1b of the constant voltage circuit 1.
The voltage division ratio between them changes. That is, when the resistors R7 and R8 are connected in parallel, the type pressure between both terminals of the variable resistor RI+, that is, the base voltage of the transistor Tr6 increases, so that the transistor Tr6 connects to the transistor Tr4 via the transistor Tr5. By reducing the conduction state of Tr3, the voltage between the output terminals 1a and 1b is made lower than when the transistor Tr7 is not turned on. That is, when the transistor T r-t is turned on, the constant voltage circuit 1 supplies the second predetermined voltage V2, which is a voltage lower than the first predetermined voltage V1, to its output terminal 1.
Output between a and 1b.

Therefore, the open coil 13 includes a transistor Tr7.
After the time TI2 when is turned on, the second predetermined voltage V2 is supplied, as shown in FIG. 2(b). As a result, after time TI2, only a small electromagnetic driving force is supplied to the shutter blade, but once the shutter blade starts moving, the static frictional force disappears, so even a small electromagnetic driving force is sufficient. In this manner, reducing the driving force once the shutter blade begins to move has the effect of reducing the influence of inertial force during movement.

Driving period T of the shutter blades by the shutter driving circuit 17
When the timing operation ends at time T32 shown in FIG. 2(d), the shutter drive circuit 17 operates as shown in FIG. 2(a).

As shown in (e) and (f), the output of the open signal from the output terminal 17a is stopped, the state of the output terminal 17c is inverted so that the transistor Tr7 is turned off, and the shutter is released from the output terminal 17b. A closing signal for closing the blade is supplied to the transistors Tr,o.

Therefore, the transistors Tr, Tr7 are turned off, the transistor Tr1o is turned on, and the open coil 1
The supply of the second predetermined voltage v2 to the coil 13 is stopped, and the generation of the electromagnetic driving force by the coil 13 disappears. At the same time, by turning off the transistor T r 7, the transistor T
r B + T r 5 + T r 4 r T r
3 returns to the initial conductive state 1, and the constant voltage circuit 1 again outputs the first predetermined voltage v1 between its output terminals 1'a and 1b. Therefore, the first predetermined voltage v1 is supplied to the opening coil 15 as shown in FIG. 2(g).

As a result, an electromagnetic driving force for closing the shutter blade is generated in the opening coil 15 after time T32.

The shutter blade starts its closing operation by the electromagnetic driving force of the opening coil 15. Specifically, as shown in Figure 2 (Ten), for example, it overcomes the influence of the electromagnetic driving force that was previously supplied to the shutter blades from the opening coil 13, and the influence of the frictional force of the shutter mechanism in the fully open state. Time point T4
2, the shutter blades actually begin to close, and at time T52
It becomes completely closed.

This completes one opening/closing operation of the shutter blade.

Note that when we look at the drive operating characteristics shown in FIG. 2(h), they appear to be the same as the characteristics of the conventional device explained in FIG. 3, but this is simply because the operating principle is the same. Their specific contents vary widely.

That is, in this embodiment, time T. Period from 2 to TI2 Time TA22 Time from TI2 to full open state 'r
22nd time period T3 A period T from 22nd time point T32 to 22nd time point T42. 2, and the period T from time T42 to time T52. 2 is a period in which the effects of ambient temperature, frictional force, etc. are taken into consideration due to the operation of the constant voltage circuit 1 and photo-interrupter device 6, respectively. That is,
In the characteristics shown in FIG. 3, for example, when the ambient temperature fluctuates, the TA-T corresponding to each period mentioned above also changes, but in the case of this embodiment, even if the ambient temperature fluctuates, the shutter blade Since the supplied electromagnetic driving force is controlled appropriately by the constant voltage circuit 1, taking into consideration the surrounding temperature, etc., the characteristics shown in Fig. 2 (11) hardly change, and the contents are It is clear that they are different.

Further, the close signal output from the shutter drive circuit 17 is
Since it is no longer necessary once the shutter blade is completely closed, it may be configured such that its generation is stopped after time TS2, for example, by a well-known timer configuration.

Furthermore, if the drive period T of the shutter blade shown in FIG. 2 ω) becomes shorter, the shutter blade does not reach the fully open state. In such a case, the closing operation of the shutter blade is performed under the supply of the second predetermined voltage V2 mentioned above, so that the influence of the inertial force of the shutter blade is small, and a highly accurate exposure control operation can be realized. become.

Effects of the Invention According to the electromagnetic shutter according to the present invention, a plurality of output voltages can be selected in consideration of ambient temperature, frictional force, etc.

Equipped with a constant voltage circuit that can be set, and the voltage is selected according to the movement state of the shutter blade, the electromagnetic driving force supplied from the opening coil or the opening coil to the shutter blade is applied until the shutter blade starts to open. It can be strengthened, weakened when it starts to open, and then strengthened when it closes, increasing speed.

Highly accurate exposure control can be achieved. In addition, since the timing operation for setting the drive period is performed according to the movement state of the shutter blade, the influence of static friction force from the start of the opening operation until the shutter blade actually begins to move can be ignored. Accurate exposure control can be achieved.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram of an embodiment of an electromagnetic shutter according to the present invention, FIGS. 2(a) to 2(g) are signal waveform diagrams for explaining the operation of this embodiment, and FIG. It is a figure which shows the drive operation characteristic of a blade|wing. FIG. 3 is a diagram that does not show the driving operation characteristics of a conventional electromagnetic shutter. 1... Constant voltage circuit, 2... Constant current circuit, 3, 7... LED, 4... Schottky diode, 5...・Release switch, 6
...Photo interrupter device, 8...
Light receiving element, 9...C-MOS inverter, 10
. . . Light control member, 11 . . . Capacitor, 12 . . . First series body, 13 . . . Open coil, 14 . 2 series body, 15...
・Opening coil, 16... Shutter opening/closing control means, 17... Shutter drive circuit, 18...
・Photometering circuit, 19...Film sensitivity detection circuit,
Tr, ~Tr, o...Transistor, R1~R
1o, R12 to RI7...Resistance, R1+...
...Variable resistance. Name of agent Patent attorney Toshio Nakao One idiot = 23- Figure 2 'To2 Top 2 Ty2 Figure 3 U-Ts -wTc-←Tp→ 1 1 1] 1 1-1-1-m-
-1 n 1 1 l
, Ya 11・1 “. Ita 1 1 1 1 1
1 ㅅda A l l l
l l 1M open:
: 1 " 1 " 0 1 l
1 1 amount
1 l 1 1 1 1 sword zk
Ta Man2man2

Claims (1)

[Claims] In an electromagnetic shutter that drives a shutter blade with an electromagnetic driving force generated in the coil by supplying a current to a coil arranged in a magnetic field, the supplied power supply voltage is adjusted to a plurality of predetermined values that take into account at least frictional force and ambient temperature. a first series circuit consisting of a constant voltage circuit that sets the voltage and selects one of the voltages and outputs it between the output terminals; a first switch element and an opening coil that are each independently connected between the output terminals; a second series body including a second switch element and a closing coil; a photointerrupter device that detects a driving state of the shutter blade and outputs a detection signal when a state corresponding to opening start is detected; By setting the driving operation period of the shutter blade in response to the subject brightness and film sensitivity, outputting a shutter blade opening signal in response to the shutter release, and further supplying a detection signal from the photointerrupter device. At the same time as starting a timing operation for the driving operation period, a control signal for appropriately selecting the output voltage of the constant voltage circuit is outputted, and when the timing operation ends, the outputting of the open signal and the control signal is stopped and the shutter is closed. An electromagnetic shutter comprising a shutter opening/closing control means that outputs a blade closing signal.