JP2001042383A - Camera shutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress variation of falling time so as to be small even though the variation of the rising time of a shutter is electrically adjusted by applying voltage adjusted at a manufacturing time to a motor driving circuit at the time of opening operation and the voltage higher than that adjusted at the time of closing operation. SOLUTION: An opening actuation start signal of shutter blades 2 and 3 is given from an information processing circuit 14 to the motor driving circuit 12 after completion of focusing. Then, the motor driving circuit 12 is connected to a constant voltage circuit 9 by a voltage selection circuit 11, so that adjusted voltage lower than the voltage set by the constant voltage circuit 9 is applied to the motor driving circuit 12. Thus, the shutter blades 2 and 3 start opening actuation. Next, when counting of exposure seconds is completed, a finish signal thereof is given to the voltage selection circuit 11, and the voltage of the constant voltage circuit 9 is directly applied to the motor driving circuit 12. Thus, an aperture part 1a is closed by actuating the shutter blades 2 and 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera shutter, usually called a lens shutter, which opens and closes a circular exposure opening by reciprocating shutter blades.

[0002]

2. Description of the Related Art In recent years, the use of electric motors has advanced, and in the case of lens shutters, motors have been used to open and close shutter blades using a motor. The motor used in this case is a stepping motor or a current-controlled motor whose rotation direction of the permanent magnet rotor is determined by the direction of current supply and which can rotate only within a predetermined angle range. Is used. And the motor of the current control is often called a moving magnet type motor in the industry, and although it is inferior in the driving force as compared with the stepping motor,
The feature is that the control system is simple and suitable for cost reduction and miniaturization. The present invention relates to a device for opening and closing the shutter blades by such a current-controlled motor. Various proposals have been made for the configuration of this type of motor, and typical ones are as follows. This is described in Japanese Utility Model Publication No. Hei 6-24815 and Japanese Patent Laid-Open Publication No. Hei 11-98800.

[0003] In addition, since the driving force of this type of motor is not so large as described above, variations in the parts manufacturing stage, such as the permanent magnet rotor and shutter blades, and variations in the assembly stage cause the opening and closing of the shutter blades. It has a very large effect on operating characteristics. Therefore, in such a case, the above-mentioned actual fairness 6-24815
As described in Japanese Patent Application Laid-Open Publication No. H11-260, an adjustment circuit is provided in a control system of each shutter, and during assembly adjustment, a shutter blade is exposed by adjusting a current and a voltage supplied to a motor drive circuit. It is known that the opening operation time (rise time) until the opening is completely changed from the pinhole to the opening is approximated to the design standard (individual difference adjustment).

In the case of a shutter in which the shutter blades are opened and closed by such a current control motor,
When the camera is not in use, the closed state of the shutter blades is
Usually, it is maintained by the magnetic force of the permanent magnet of the rotor. That is, even when the motor is not energized, the attractive force of the permanent magnet rotor between the rotor and the stator causes the rotor to rotate in the direction opposite to the opening operation direction of the shutter blade. It is kept in a closed state by keeping it in a state of being stopped by a predetermined stopper.

[0005] For this reason, when the stator coil is opened in the forward direction by energizing the stator coil at the time of photographing, the opening operation is performed against the above-mentioned suction force. When the shutter blades perform the closing operation by energizing in the direction, the closing operation is performed by applying the above-described suction force. Therefore, the shutter blade performs the closing operation relatively earlier than the opening operation, and the opening and closing operation characteristic of the shutter blade is the magnitude of the suction force when the closed state is maintained. Will greatly depend on Therefore, conventionally, even when such a variation in the suction force occurs during the manufacturing, the current supplied to the motor drive circuit and the current supplied to the motor drive circuit are controlled as described in Japanese Utility Model Publication No. 6-24815. The individual difference was adjusted by adjusting the voltage and obtaining a predetermined rise time.

[0006]

However, individual differences in the rise time are adjusted as described above on the basis of the variation in the suction force for maintaining the closed state, and the shutter blade is closed by the shutter blade before full opening. If it is attempted to properly perform the control for starting the exposure or the synchronization control of the flash, on the contrary, a large variation occurs in the closing operation time (fall time) of the exposure aperture. There was a point. Therefore, this will be described in detail with reference to FIG.

FIG. 3 shows the opening / closing operation characteristics of the shutter blade. The solid line (x mark) indicates that the predetermined opening / closing operation characteristics can be obtained at a predetermined voltage (for example, 1.3 V) according to the design standard. It shows the case where it was done. In this case, as described above, the closing operation is faster than the opening operation. Also, due to variations in production (individual differences),
When the suction force acting in the shutter closed state is weaker than in the case of the design standard, even if the applied voltage is the same, as indicated by the dashed line with a circle, the case is lower than in the case of the design standard. The opening action is faster and the closing action is slower. Conversely, when the suction force acting in the shutter closed state is stronger than in the case of the design standard, the opening operation is slower than in the case of the design standard, Will be faster. Therefore, the variation width of the fall time in this case is the time A shown in FIG.

Therefore, a voltage (for example, 1.2 V) lower than the reference voltage (1.3 V) is applied in the case of the dot-dash line by the individual difference adjustment, and in the case of the dotted line by the triangle, , A voltage higher than the reference voltage (1.3 V) (for example,
It is assumed that a rise time similar to that of the solid line can be obtained by applying the voltage of 1.4 V). However, when such an adjustment is made, even if the rise time is close to the design standard, the fall of the fall time is conversely large.

That is, in the case of the one-dot chain line, the attractive force in the closing direction due to the magnetic force of the permanent magnet is originally small, and the applied voltage is lower than the reference voltage. The falling time becomes extremely long, as indicated by the -1 mark. In the case of the broken line, the attractive force in the closing direction due to the magnetic force of the permanent magnet was originally large, and it was higher than the reference voltage. Therefore, the fall time is further shortened as indicated by the mark △ -1 than that of the mark △, and the variation width thereof is longer than the above-mentioned time A and becomes the time B. There is a point.

In the above description, the variation of the fall time in the case of the broken line is larger than the variation of the fall time of the alternate long and short dash line in FIG. 3 while the voltage adjustment value is the same 0.1 V. Although it is smaller, it is needless to say that the fall time in the case of the design standard is set as short as possible while considering the load of the shutter blades and the like (the same applies to the rise time). As described above, since this type of motor does not have very good driving force, even if the same adjustment is made to the side where the applied voltage is increased and the side where the applied voltage is decreased, the fall of the design standard This is because the adjustment effect is less likely to appear in a direction in which the time is shorter than the time.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to make it possible to electrically adjust the variation in the rise time of the shutter blade at the time of manufacture, and to reduce the fall time. An object of the present invention is to provide a current-controlled motor-driven camera shutter that does not require a large variation in time.

[0012]

In order to achieve the above object, a camera shutter according to the present invention comprises a predetermined number of shutter blades for opening and closing an exposure opening by reciprocating operation, and a predetermined angle in different directions depending on the direction of energization. A motor having a permanent magnet rotor that rotates only within a range and causing the shutter blade to perform opening and closing operations; and a detecting unit that detects a plurality of operating positions of the shutter blade to measure an opening speed of the shutter blade. A motor drive circuit for supplying currents to the motor in different directions when the shutter blades are opened and closed, an exposure control circuit for outputting a close signal at a timing corresponding to exposure conditions, A constant voltage circuit capable of applying a voltage to the motor drive circuit; and a constant voltage circuit based on a detection result of the detection means when the shutter is manufactured. A voltage adjusting circuit capable of adjusting a voltage applied to the motor driving circuit; and a voltage adjusted by the voltage adjusting circuit applied to the motor driving circuit when the shutter blade is opened, and a closing signal is received from the exposure control circuit. And a voltage selection circuit for directly applying a voltage from the constant voltage circuit to the motor drive circuit. Further, in the camera shutter according to the present invention, it is preferable that an initial position detection signal of the shutter blade by the detection means is a control start signal of the exposure control circuit.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the illustrated embodiments. First, the configuration of the present embodiment will be described with reference to FIG. The shutter base plate 1 has an opening 1a at the center thereof for regulating the exposure opening, and forms a blade chamber between the shutter base plate 1 and an auxiliary base plate (not shown) arranged on the back side. The auxiliary base plate also has a planar shape similar to that of the shutter base plate 1, and has an opening having the same shape as the opening 1a at a position overlapping the opening 1a. Further, a long hole 1b and a window 1c penetrating to the blade chamber are formed in the shutter base plate 1, and inside the blade chamber,
Two shafts 1d and 1e and two stoppers 1f and 1g are provided.

In the blade chamber, two shutter blades 2, 3 are provided.
Is arranged. The shutter blade 2 includes the shaft 1
d, which is rotatably mounted and has a long hole 2a, a detected portion 2b, and a tip 2c. The other shutter blade 3 is rotatably attached to the shaft 1e, and has a long hole 3a, a detected portion 3b, and a tip 3c.

A photodetector and a current control motor are mounted on the front side of the shutter base plate 1 (the subject side when incorporated in the camera). However, since these configurations are all well known, they are schematically shown so as not to complicate the drawings and to make it possible to understand only the basic configurations. First, the photodetector of the present embodiment is a photoreflector 4, in which a light emitting portion 4a and a light receiving portion 4b face a long hole 1b. The light emitted from the light emitting unit 4a is reflected in the blade chamber, and the reflected light is received by the light receiving unit 4b.

The motor of this embodiment has a rotor 5 of a permanent magnet magnetized to two poles, a coil 6 of a stator, and a magnetic member 7 attached to the stator. A drive pin 5a is provided at a position protruding from the rotor 5 in the radial direction. The drive pin 5a is connected to the window 1c.
The shutter blades 2 and 3 are inserted into the elongated holes 2a and 3a of the shutter blades 2 and 3 so as to open the shutter blades 2 and 3 in accordance with the rotation direction of the rotor 5,
The closing operation is performed.

Further, the control system of the motor includes a power source 8 and
Constant voltage circuit 9, voltage adjustment circuit 10, voltage selection circuit 1
1, a motor drive circuit 12, an exposure control circuit 13, and an information processing circuit 14, and the voltage selection circuit 11
The constant voltage circuit 9 can be directly connected to the motor drive circuit 12 or can be connected via the voltage adjustment circuit 10. Also, needless to say, the case where the connection is made via the voltage adjustment circuit 10 is better than the case of the constant voltage circuit 9.
Are directly lower than the voltage applied to the motor drive circuit 12.

Next, the operation of this embodiment will be described with reference to the timing chart of FIG. FIG. 1 shows a closed state of the shutter. At this time, the coil 6 is not energized. However, the rotor 5 is given a rotating force in the counterclockwise direction by the magnetic force of the permanent magnet. This is because the attractive force is exerted by the magnetic force of the permanent magnet such that the peripheral central portion of the S pole of the rotor 5 is located on the line connecting the rotation axis of the rotor 5 and the magnetic member 7.

Then, the rotational force in the counterclockwise direction is transmitted to the shutter blades 2 and 3 via the drive pin 5a, and rotates the shutter blade 2 counterclockwise on the shaft 1d.
The shutter blades 3 function to rotate the shutter blades 3 clockwise about the shaft 1e.
Since c and 3c are in contact with stoppers 1f and 1g, this closed state is maintained. The drive pin 5a may be brought into contact with the upper edge of the window 1c in order to prevent the rotor 5 from rotating in the counterclockwise direction.

When a power switch (not shown) is closed prior to photographing, the exposure control circuit 13 controls the exposure time based on information such as the brightness of the subject and the film sensitivity. (Not the exposure time) can be started, and various warning circuits can be activated. Further, at this time, since the photoreflector 4 is also energized, the light emitted from the light emitting section 4a is reflected by the reflection means in the blade chamber,
The reflected light enters the light receiving unit 4b. In FIG. 2, such an incident state is referred to as “light transmission” for convenience, and a state where no light is incident is referred to as “shielded”.
Note that the control time can be changed in accordance with a change in subject brightness during shooting.

Next, when the shutter is released, an automatic focusing device (not shown) operates to perform focusing. When the focusing is completed, a shutter blade opening operation start signal is sent from the information processing circuit 14 to the motor driving circuit 12. Given to. At this time, since the voltage selection circuit 11 connects the motor drive circuit 12 to the constant voltage circuit 9 via the voltage adjustment circuit 10, the motor drive circuit 12 Therefore, a low adjustment voltage is applied, and a current corresponding to the adjustment voltage is supplied to the coil 6 in the forward direction. Thereby, the rotor 5 is rotated clockwise, and the shutter blades 2 and 3 are started to open by the drive pin 5a.
The arrows between the circuits in FIG. 1 indicate the information transmission directions.

When the shutter blades 2 and 3 open, the detected portion 2b of the shutter blade 2 blocks the optical path of the photo reflector 4 until the opening 1a is brought into the pinhole state. Therefore, the exposure control circuit 13 starts counting the number of exposure seconds in response to a signal from the information processing circuit 14 based on the detection signal of the start of cutoff. Thereafter, when the state becomes substantially pinhole, the detected portion 2b of the shutter blade 2
Releases the light-shielding state of the photo-reflector 4 and opens the opening 1a.
And then the detected part 3b of the shutter blade 3
Cuts off the optical path of the photoreflector 4, and then, just before the opening 1a is fully opened, the light blocking state is released. The opening operation of the shutter blades 2 and 3 performed in this manner is stopped after the drive pin 5a comes into contact with the lower edge of the window 1c after the opening 1a is fully opened.
As can be seen from FIG. 2, even in such a stopped state, energization of the coil 6 continues.

Next, when the counting of the exposure time by the exposure control circuit 13 is completed, the end signal is sent to the voltage selection circuit 1.
1, the voltage of the constant voltage circuit 9 is directly applied to the motor drive circuit 12, and the voltage of the coil 6 is
Electric power is supplied from the motor drive circuit 12 in the reverse direction.
Therefore, the rotor 5 is rotated in the counterclockwise direction more quickly than in the opening operation, and the shutter blades 2 and 3 are operated by the drive pin 5a to close the opening 1a. Immediately after closing the opening 1a, the shutter blades 2,
Reference numeral 3 denotes a power supply to the coil 6 after a lapse of a predetermined time from when the light-shielding state of the photoreflector 4 by the detected portion 2b of the shutter blade 2 is released by stopping the tip portions 2c and 3c against the stoppers 1f and 1g. Is cut off to obtain the state shown in FIG. In the present embodiment, it has been described that, in the state of FIG. 1, the voltage selection circuit 11 has already been in the selected state of the voltage adjustment circuit 10, but this state is the shutter blade opening operation start signal. It goes without saying that the selection may be made by the user.

Therefore, next, in addition to FIGS. 1 and 2, FIG.
The method of adjusting the individual difference of the rise time at the time of manufacturing the present embodiment, and how the problem of the present invention is solved in the present embodiment, The description will be made so as to be easily compared with the case.
First, in the case of the present embodiment, the set voltage of the constant voltage circuit 9 is 1.5V. In addition, as in the case of the above-described conventional example, when the voltage of 1.3 V is applied to the motor drive circuit 12, the open / close operation characteristics of the design standard are as shown by the solid line in FIG. Stipulated. In order to measure the actual rise time, a special measuring device must be prepared. Therefore, in this embodiment, the measurement target of the rise time is the photoreflector 4 by the detected portion 2b of the shutter blade 2. The time from the end of the light-shielding state to the end of the light-shielding state of the photoreflector 4 by the detected portion 3b of the shutter blade 3 is defined as t (see FIG. 2).

Therefore, at the time of manufacture, a voltage of 1.3 V is applied to the motor drive circuit 12 of each shutter via the voltage adjustment circuit 10, and the rise time defined as described above is measured. . If the measured value is shorter than the rise time t of the design standard, the voltage applied via the voltage adjustment circuit 10 is set lower than 1.3 V, and if longer, the voltage is set higher than 1.3 V. Thus, the same rise time t as the design standard is obtained.

When the measured rise time is shorter than the design standard, as indicated by the dashed line in FIG. 3, the voltage applied to the motor drive circuit 12 by the voltage adjustment circuit 10 is 1. Adjust to 2V, and
As shown by the broken line, when the voltage is longer than the case of the design standard, the voltage applied to the motor drive circuit 12 is adjusted to 1.4 V so that the rise time t of the design standard is obtained. This is exactly the same as the conventional case. However, as described above, if such adjustment is made, even if the variation in the rise time can be eliminated, the variation width in the fall time becomes large as shown by B in FIG.

Therefore, in the case of this embodiment, in the closing operation, a voltage of 1.5 V is directly applied from the constant voltage circuit 9 to the motor drive circuit 12. Then, in the case of the dashed line, the applied voltage is 0.3 V higher than the applied voltage at the time of the opening operation, and in the case of the broken line, it is 0.1 V higher. Then, there is a difference in the plus voltage value between the two, and the shorter the fall time, the smaller the amount of time reduction for a given plus voltage value. As shown in FIG. 3, the closing operation characteristic of
, And the broken line is shown as △ -2. Therefore, the one with the dashed line has a fall time much shorter than that of the case of ―-1, and the one with the broken line becomes slightly shorter than the case of △ -1. Not only is it small, but also smaller than A before the rise time is adjusted.

[0028]

As described above, according to the present invention, the shutter blades are opened and closed by the reciprocating rotation of the current control motor having the permanent magnet rotor, and the closed state is set between the rotor and the stator. In a motor-driven camera shutter that is maintained by utilizing the magnetic attraction that acts,
When performing the opening operation, a voltage adjusted at the time of manufacturing is applied to the motor drive circuit, and when performing the closing operation, a voltage higher than the adjusted voltage is applied from the constant voltage circuit. Therefore, even if the variation in the rise time of the shutter is electrically adjusted, the variation in the fall time can be suppressed to be small.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment.

FIG. 2 is a timing chart for explaining the operation of the embodiment.

FIG. 3 is an opening / closing operation characteristic diagram for explaining variation in fall time of shutter blades in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shutter base plate 1a Opening 1b, 2a, 3a Slot 1c Window 1d, 1e Shaft 1f, 1g Stopper 2, 3 Shutter blade 2b, 3b Detected portion 2c, 3c Tip 4 Photoreflector 4a Light emitting portion 4b Light receiving portion 5 Rotor 5a Drive pin 6 Coil 7 Magnetic member 8 Power supply 9 Constant voltage circuit 10 Voltage adjustment circuit 11 Voltage selection circuit 12 Motor drive circuit 13 Exposure control circuit 14 Information processing circuit

Claims (2)

[Claims] 1. A reciprocating operation includes a predetermined number of shutter blades for opening and closing an exposure opening, and a permanent magnet rotor that rotates by a predetermined angle range in a direction different depending on a current supply direction, and performs opening and closing operations on the shutter blades. Motor to
Detecting means for detecting a plurality of operating positions of the shutter blade in order to measure the opening speed of the shutter blade, and supplying currents in different directions to the motor during the opening operation and the closing operation of the shutter blade Motor drive circuit,
An exposure control circuit that outputs a close signal at a timing corresponding to the exposure condition; a constant voltage circuit that can apply a predetermined voltage to the motor drive circuit; and a shutter that manufactures a shutter based on a detection result of the detection unit. A voltage adjusting circuit capable of adjusting a voltage applied from the voltage circuit to the motor driving circuit; and a voltage adjusted by the voltage adjusting circuit applied to the motor driving circuit during the opening operation of the shutter blade when the shutter blades are opened. A camera shutter, comprising: a voltage selection circuit for directly applying a voltage from the constant voltage circuit to the motor drive circuit when receiving a close signal. 2. The camera shutter according to claim 1, wherein an initial position detection signal of said shutter blade by said detection means is a control start signal of said exposure control circuit.