JP3448349B2 - Lens shutter trigger detection level adjustment mechanism - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for adjusting a detection level of a trigger signal in a lens shutter for a camera of a type in which a photo sensor detects a movement of a shutter blade to obtain a trigger signal, and particularly to cost reduction. The present invention relates to a trigger detection level adjustment mechanism that can be downsized, and can be adjusted with high accuracy.

[0002]

BACKGROUND OF THE INVENTION shutter blade pivotally mounted on one side of the exposure opening is reciprocating, a camera to be controlled by the exposure control circuit that closed during machine with thereby to open and close the exposure opening Shutters are known. In this type of shutter, the control start signal of the exposure control circuit, that is, the trigger signal is obtained by detecting the operating position of the shutter blade in the initial stage of its operation. As the detecting means, usually, a photosensor called a photoreflector, a photointerrupter or the like is often used.

By the way, the detection level of the trigger signal by the photosensor (hereinafter referred to as "trigger detection level") and the timing for obtaining this signal (hereinafter referred to as "trigger timing") are provided in the exposure control circuit and the camera. In consideration of various control circuits currently used, it is required to obtain a predetermined detection level and a predetermined timing. However, it is difficult to obtain this trigger signal at a predetermined detection level and at a predetermined timing because there are variations in the light emission intensity of individual photosensors, errors in the mounting positions of the photosensors, and deviations of the optical axis of the photosensors. Is.

In order to correct the variation in the trigger timing, a method of incorporating a delay circuit into the exposure control circuit and adjusting the delay circuit has been conventionally used, but this makes the exposure control circuit complicated and reduces the manufacturing cost. It had the drawback of increasing. Therefore, as a conventional example for solving this problem, a trigger timing adjusting mechanism as shown in FIGS. 5 and 6 is disclosed in Japanese Utility Model Laid-Open No. 122429/1993.

According to this trigger timing adjusting mechanism, the guides 64, 64 formed on the shutter base plate 61 for guiding the photosensor (photointerrupter) 65 in the tangential direction of the peripheral edge of the shutter blade 63, and the photosensor 65. The adjustment shaft 66 pivotally mounted and having the eccentric shaft portion 66b is formed on the shutter base plate 61 so that the longitudinal direction thereof coincides with the direction intersecting the tangential direction, and the eccentric shaft portion 66b is slidably fitted thereto. The photo sensor 65 is composed of a long hole 67, and the adjustment shaft 66 is rotated to finely move the photo sensor 65 along the guide.
By changing the relative position with respect to the peripheral portion of No. 3, it is possible to correct the variation of the trigger timing with an extremely simple mechanical configuration without using a delay circuit.

On the other hand, in order to correct the variation in the trigger detection level, it is necessary to deal with the variation in the output level of the photo sensor itself. In order to keep the output level within the desired range, it is conceivable to purchase a photosensor with a high selection rank that is carefully selected so that the received light level falls within the specified range. If a photosensor with a light receiving level within a predetermined range is adopted after purchasing a photosensor with a relatively large level variation, the proportion of photosensors that can be adopted will decrease, and in any case, the manufacturing cost of the lens shutter device will be reduced. Will increase. Therefore, in order to cope with the variation in the light receiving level of the photo sensor itself while achieving a significant cost reduction, it is possible to purchase a photo sensor with a relatively gentle selection rank and to use almost all of them. There is a need. for that purpose,
It is necessary to adjust the light receiving level of the photo sensor having a light receiving level higher than this by adjusting the reference to the one having the lowest light receiving level among the purchased sensors.

As described above, as a conventional example for correcting the variation of the trigger detection level, for example, an actual flat plane 1
An adjusting circuit as disclosed in FIG. 2 of Japanese Patent No. 59231 is provided, and the resistance provided inside the adjusting circuit is adjusted (selected or changed) in order to correspond to the level of the light receiving level of the photosensor. Things are known.

[0008]

However, if the trigger detection level is corrected by providing the adjustment circuit as described above, in order to improve the accuracy of the trigger detection level, it is possible to cope with the high and low light receiving levels of the photosensor. Therefore, it is necessary to prepare a plurality of resistors, which results in an increase in manufacturing cost of the lens shutter device and an increase in space.

Although it is possible to adjust the trigger detection level by using a variable resistor without preparing a plurality of resistors, it is necessary to prepare an expensive variable resistor, and in this case also, the lens shutter device. However, there is a drawback that the manufacturing cost and the space are increased.

Further, it is conceivable that the detection level of the trigger signal is adjusted by the trigger timing adjusting mechanism, but in the above configuration, the relative position of the photo sensor and the peripheral edge of the shutter blade is set to the peripheral edge of the shutter blade. It can only be adjusted tangentially and the detection level of the trigger signal cannot be varied. Therefore, the detection level of the trigger signal cannot be adjusted by the trigger timing adjusting mechanism.

Furthermore, the photosensor used in the above-mentioned trigger timing adjusting mechanism has a U-shaped cross section as shown in FIG. 6, and the light receiving section directly receives the light from the light emitting section. Although it is a so-called photo interrupter that receives light, it is extremely difficult to finely mechanically adjust the light receiving state of the light receiving portion and adjust the detection level in the photo sensor of this type.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the prior art, and its purpose is to:
This is to make the adjustment circuit of the trigger detection level unnecessary, and to reduce the manufacturing cost of the lens shutter device and to downsize the lens shutter device by making the adjustment possible mechanically.

Another object is to make unnecessary the selection work of the photosensors on the basis of the predetermined light receiving level, and to make all the photosensors in the predetermined light receiving level rank purchased usable. Yes, this also reduces the manufacturing cost of the lens shutter device.

Still another object is to enable easy and highly accurate adjustment of the trigger detection level.

[0015]

In order to achieve the above object, the present invention provides a control start signal for an exposure control circuit.
In the photo sensor, the light receiving section receives the reflected light of the light emitted from the light emitting section to the traveling area of the shutter blades,
Areas of the emission surface of the light emitting portion and the incident surface of the light receiving portion due to changes in relative positions of the light emitting portion and the light receiving portion of the photo sensor
And a shutter base plate formed with a hole for adjusting the intensity of light in the light receiving section, and a means capable of moving the photosensor with respect to the shutter base plate in a direction substantially parallel to the traveling surface of the shutter blades. It is characterized by having and.

Still further, according to the present invention, means capable of moving the photosensor in the parallel direction with respect to the shutter base plate guides the photosensor so as to be movable in predetermined forward and reverse directions. Therefore, a guide portion formed on the shutter base plate, an adjustment shaft pivotally attached to the shutter base plate and having an eccentric shaft portion, and a movable unit provided to carry the photo sensor and intersect the forward and reverse directions. It is preferable that the substrate has a long hole which is formed so that the longitudinal direction thereof coincides with the above-mentioned direction and which is slidably fitted to the eccentric shaft portion.

Further, in the present invention, it is preferable that the forward and reverse directions are tangential directions of the exposure aperture.

[0018]

In the lens shutter trigger detection level adjusting mechanism according to the present invention, the photosensor fixed to the substrate is rotated along the guide portion formed on the shutter base plate by rotating the adjusting shaft on the shutter base plate. The photo sensor is moved in a direction parallel to the shutter base plate, for example, by slightly moving the photo sensor to change the relative positional relationship between the light emitting / receiving parts of the photo sensor and the holes formed in the shutter base plate.
As a result, the light receiving level of the photo sensor is adjusted and a predetermined trigger detection level by the photo sensor is obtained.

[0019]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a plan view showing an initial state before a shutter of a lens shutter device having a trigger detection level adjusting mechanism of the present invention is opened, and FIG. 2 is a plan view mainly showing the trigger detection level adjusting mechanism. 3 is A of FIG.
-A arrow sectional view, FIG. 4 is a BB arrow sectional view of FIG.

First, the structure of the lens shutter device will be described. An exposure opening 1a and a substantially arc-shaped hole 1b are formed in the shutter base plate 1. On the plane portion of the shutter base plate 1, pedestals 1c and 1d, convex portions 1e and 1f are formed, and a side surface portion 1g extending rearward in the drawing is formed. A pair of guide portions 1h directed in the tangential direction of the exposure opening 1a are formed between the convex portions 1e and 1f. In order to easily assemble the photo sensor 5 in a stable manner, it is preferable that the guide portion 1h has a convex portion 1h-1 and a concave portion 1h-2 as shown in FIGS. 3 and 4. In this embodiment, as long as the photosensor 5 can be guided movably in the tangential direction, the photosensor 5 may have either the convex portion 1h-1 or the concave portion 1h-2.

Also, the shutter base plate 1 has a long hole 1i.
Is provided so that its longitudinal direction is a direction intersecting the tangential direction. Further, the convex portion 1f has a structure shown in FIG.
Shaft 1j is planted as shown in, and the convex portion 1e has
A hole 1k is provided. Further, as is well known, the base plate 1 and the cover plate 7 shown in FIGS. 3 and 4 form a blade chamber.

The shutter blades 3 and 4 are housed in the above-mentioned blade chamber, and the shutter base plate 1 is provided with respective shafts 3a and 4a.
Is pivotally attached to. The shutter blades 3 and 4 are formed with slots 3b and 4b, and the outer edge 4c of the shutter blade 4 is formed with a protruding portion 4d as a detected portion.

A photosensor 5 for detecting the protrusion 4d is arranged between the protrusions 1e and 1f formed on the shutter base plate 1. The photosensor 5 is a photoreflector whose reflected light of the light emitted from the light emitting portion 5a is received by the light receiving portion 5b, and has a maximum level when the line 5c connecting the light emitting / receiving center is located at the center of the hole 1i. It is configured to generate a trigger signal. And
The photo sensor 5 is connected to an exposure control circuit (not shown), and the trigger control signal activates the exposure control circuit. The light emitting section 5a and the light receiving section 5b
Is not particularly limited to the arrangement as shown in FIG. 2, and may be mutually replaced arrangements. Further, the photosensor 5 has four terminals 5d, and as shown in FIG. 3, the terminals 5d are carried by being fixed to the substrate 8 with solder or the like, and as shown in FIG. The shutter base plate 1 is arranged so as to cover the hole 1i and can be slid in the tangential direction by being guided by the guide portion 1h.

FIG. 1 shows a moving magnet type motor 6 known as an actuator for opening and closing the shutter blades 3, 4. This motor 6 has its substrate 6
It is attached to the pedestals 1c and 1d at a. Rotor 6b
A coil 6d is wound around the stator 6c that rotatably supports the rotor 6b so as to cover the bearing portion of the rotor 6b, and a yoke 6e is provided outside the coil 6d. A drive pin 6g is provided in the arm 6f formed integrally with the rotor 6b in a direction perpendicular to the paper surface.
The drive pin 6g is provided on the shutter base plate 1
Through the arc-shaped hole 1b formed in the shutter blade 3,
4 slots 3b, 4b are fitted. The motor 6 rotates the rotor 6b in the forward direction when a current is supplied to the coil 6d in the forward direction, and rotates the rotor 6b in the reverse direction when a current is supplied in the reverse direction. There is.

The substrate 8 is attached to the convex portion 1e and the convex portion 1f. The substrate 8 is provided with elongated holes 8a such that the longitudinal direction thereof intersects the tangential direction described above. The substrate 8 is also provided with a long hole 8b that slides on a shaft 1j planted in the convex portion 1f of the shutter base plate 1 so that the longitudinal direction thereof coincides with the tangential direction.

As shown in FIG. 3, the adjusting shaft 9 includes a tip central shaft portion 9b pivotally attached to a hole 1k provided in the convex portion 1e of the shutter base plate 1 and an elongated hole formed in the substrate 8. 8a
And an eccentric shaft portion 9a that is slidably fitted to the. A groove 9c is provided on the head of the adjusting shaft 9 so that a driver or the like can be engaged to rotate the adjusting shaft 9.

As shown in FIGS. 3 and 4, a reflection sheet 10 is attached to the cover plate 7 so that the light emitted from the light emitting portion 5a of the photosensor 5 can be reflected to the light receiving portion 5b. It is arranged. And the reflection sheet 1
0 and the light emitting portion 5a and the light receiving portion 5b are connected to each other by the protruding portion 4d.
Is configured to generate a trigger signal by passing.

Next, the operation of the shutter configured as described above will be described. When the release button of the camera is pressed at the time of shooting, first, the distance to the subject is measured, and a stepping motor (not shown) is rotated according to the distance measurement signal to extend the lens and set it at a predetermined focus position. . At this focus adjustment stage, the photo sensor 5 is energized, and the light emitted from the light emitting portion 5a passes through the long hole 1i provided in the shutter base plate 1 and reaches the cover plate 7 without being blocked by the shutter blades 4. Attached reflective sheet 1
The reflected light is reflected by 0, and the reflected light passes through the long hole 1i provided in the shutter base plate 1 and is received by the light receiving portion 5b of the photo sensor 5. Therefore, the photo sensor 5 at this stage has obtained a predetermined light receiving level and outputs a predetermined signal (for example, a HIGH signal).

Thereafter, when a forward current is supplied to the coil 6d of the motor 6, the rotor 6b is rotated counterclockwise in FIG. At this time, the arm 6f also rotates counterclockwise, so the drive pin 6g
Thus, the shutter blade 3 is rotated counterclockwise about the shaft 3a, and the shutter blade 4 is rotated clockwise about the shaft 4a.
The shutter blade 4 has the outer edge 4 at the initial stage of its opening operation.
covering more holes 1i the protrusion 4d which is formed to c. Therefore, the light receiving section 5b of the photosensor 5 is shielded from the light from the light emitting section 5a and outputs, for example, a LOW signal. This signal becomes the trigger signal. At this time, the exposure opening 1a is not yet opened by the shutter blades 3 and 4. Then, when this trigger signal is generated, an electronic circuit (not shown) starts control for the exposure time. Shutter blades 3, 4
Then reaches the pinhole position and opens the exposure opening 1a.

When a predetermined time has elapsed according to the photometric value of the object, the coil 6 is activated by the signal from the electronic circuit described above.
An electric current in the opposite direction different from the above is supplied to d. Therefore, the rotor 6b is rotated clockwise, and the drive pins 6g actuate the shutter blades 3 and 4 in the opposite direction to the above to close the exposure opening 1a. After that, the power supply to the coil 6d is cut off, and the shutter blades 3 and 4 stop at the initial position shown in FIG. In this way, the exposure is completed.

Next, the adjustment of the trigger signal detection level in the above shutter will be described. In FIG. 2, if a screwdriver or the like is engaged with the groove 9c provided on the head of the adjustment shaft 9 to rotate the adjustment shaft 9, the eccentric shaft portion 9a thereof is formed.
The eccentric action of the
Finely moves in the direction guided by h. As a result, the relative positional relationship between the light emitting portion 5a / light receiving portion 5b of the photosensor 5 and the long hole 1i formed in the shutter base plate 1 changes,
The areas of the emission surface and the incidence surface of the light emitting portion 5a and the light receiving portion 5b change. As a result, the intensity of the light emitted from the light emitting unit 5a reaching the reflection sheet 10 and the intensity of the light reflected by the reflection sheet 10 received by the light receiving unit 5b of the photosensor 5 are changed. To be That is, the trigger detection level is changed.

After being adjusted to a predetermined level position,
The substrate 8 is fixed to the shutter base plate 1 with, for example, an adhesive. This is to prevent the level from changing again after adjusting the trigger detection level. Further, as long as it can be fixed to the shutter base plate 1, a screw or the like (not shown) may be used without using an adhesive agent, or a combination thereof may be used for fixing.

As described above, according to this embodiment, it is possible to adjust the variation in the trigger detection level with a simple mechanical structure without using an adjusting circuit. In this case, since the relative position between the hole 1i provided in the shutter base plate 1 and the shutter blade 4 is kept constant, the photo sensor 5 is used to adjust the variation in the trigger detection level.
In the case of (1), if it is moved in the direction of the axis 1j, the trigger timing will not shift.

Further, in FIG. 1, the shutter blades 3,
Since a moving magnet type motor 6 is used as a drive device for driving No. 4, since there is a sufficient space between the peripheral edge portion 4d of the shutter blade 4 and the outer diameter portion of the shutter base plate 1, there is no particular problem. Depending on the configuration of the drive device for the blades 3 and 4, the photosensor 5 is configured to be guided in the tangential direction of the exposure opening 1a as shown in this embodiment, so that the substrate 8 may cover the exposure opening 1a. Since it does not exist, it is possible to suppress the radial dimension of the shutter base plate 1 from increasing, which is advantageous for downsizing the lens shutter device.

However, if there is no problem in space, unlike the above, the guide portion 1h is formed so as to guide the photosensor 5 in the optical axis direction, and the elongated hole 8a formed in the substrate 8 is formed. A long hole 1i formed in the shutter base plate 1 so that its longitudinal direction coincides with the tangential direction.
May be configured such that its longitudinal direction coincides with the tangential direction.

Further, as shown in the present embodiment, the hole 1i formed in the shutter base plate 1 is a long hole whose longitudinal direction extends in the direction intersecting the adjusting movement direction of the substrate 8, which is a long hole. This is because, in consideration of the manufacturing cost of the shutter base plate 1, unlike the present embodiment, the light emitting section 5a.
Two holes 1i may be provided for each light receiving portion 5b. Further, the long hole 1i may be a round hole if there is no concern about light leakage.

Further, in this adjusting mechanism, the photo sensor 5 is arranged in the direction parallel to the shutter base plate 1, that is, the shutter blades 3, 3.
The configuration of the present embodiment is not limited as long as it is a configuration that uses a unit that can move in a direction parallel to the traveling surface of No. 4. For example, the guide portion 1h may be removed from the configuration of the present embodiment to allow movement in multiple directions. In that case, when the adjustment shaft 9 is rotated,
The photo sensor 5 follows the eccentric action of the eccentric shaft portion 9a.
It slightly moves in the optical axis direction and slightly moves in the tangential direction of the exposure opening 1a.

Further, from the configuration of this embodiment, the guide portion 1h
Alternatively, instead of the elongated hole 8a, a round hole having a diameter slightly larger than that of the eccentric shaft portion 9a fitted into the eccentric shaft portion 9a may be provided. In that case, when the adjustment shaft 9 is rotated, the photosensor 5 finely moves in the optical axis direction or in the tangential direction of the exposure opening 1b due to the eccentric action of the eccentric shaft portion 9a.

Further, from the structure of this embodiment, the guide portion 1h,
The long hole 8a and the adjusting shaft 9 may be removed, and instead of the long hole 8b, a round hole that allows the shaft 1j planted in the shutter base plate 1 to pass therethrough may be provided. In this configuration, the photosensor 5 can move in the concentric direction about the axis 1j.

Similarly, the guide portion 1h, the elongated hole 8b and the shaft 1j are removed from the construction of this embodiment, and the eccentric shaft portion 9a of the adjusting shaft 9 is made to be a concentric shaft portion. Good. In this configuration, the photo sensor 5 can move in the concentric direction about the concentric shaft portion.

Further, the substrate 8 may be removed from the structure of this embodiment, and a structure may be used in which the photosensor 5 can be directly moved in parallel to the shutter base plate 1. In this case, the above-mentioned means may be an adjusting shaft having an eccentric shaft portion, and after the photosensor 5 is moved and adjusted to a predetermined level position, the photosensor 5 is fixed to the shutter base plate 1 with, for example, an adhesive. Is preferred.

In short, in the present invention, the light receiving level of the photosensor 5 is changed by changing the relative positions of the light emitting portion 5a / light receiving portion 5b of the photosensor 5 and the elongated hole 1i formed in the shutter base plate 1. Other configurations than the above may be used as long as they can be adjusted.

[0043]

As described above, the present invention can correct the variation in the trigger detection level with an extremely simple mechanical structure without using the circuit for adjusting the trigger detection level. As a result, the manufacturing cost of the lens shutter device can be reduced, and the lens shutter device can be downsized.

Furthermore, since the allowable light-reception level range can be widened, the selection of photosensors based on the predetermined light-reception level can be eased, and as a result, the manufacturing cost of the lens shutter device can be reduced. effective.

Furthermore, in changing the relative positions of the light emitting / receiving parts of the photosensor and the holes formed in the shutter base plate in order to adjust the light receiving level of the photosensor, parallel movement in multiple directions is possible. Therefore, there is an effect that the trigger detection level can be adjusted variously and elastically.

Furthermore, when an adjusting shaft having an eccentric shaft portion is provided, the relative position between the light emitting portion / light receiving portion of the photosensor and the hole formed in the shutter base plate is rotated by rotating the adjusting shaft. The light receiving level of the photo sensor can be changed to a predetermined level, and as a result, the trigger detection level can be adjusted with high accuracy by a simple operation.

As described above, according to the present invention, it is possible to dramatically improve the manufacturing cost, work efficiency and manufacturing quality of the lens shutter device, and eventually to supply a high quality product at a low price to the market. Therefore, the industrial effect is extremely large.

[0048]

[Brief description of drawings]

FIG. 1 is a schematic plan view showing an embodiment of an entire lens shutter device provided with a trigger detection level adjusting mechanism according to the present invention, showing a shutter closed state.

FIG. 2 is an enlarged plan view of a trigger detection level adjusting mechanism according to the present invention.

FIG. 3 is a sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view taken along the line BB of FIG.

FIG. 5 is a plan view showing a conventional example of a trigger timing adjusting mechanism.

6 is a cross-sectional view taken along the line CC of FIG.

[Explanation of symbols]

1 Shutter base plate 1a Exposure aperture 1h Guide section 1i, 8a long hole 3,4 shutter blades 5 Photo sensor 5a light emitting part 5b Light receiving part 5c Line connecting the centers of light emission and light reception 7 Cover plate 8 substrates 9 adjustment axis 9a Eccentric shaft 10 Reflective sheet

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03B ^7/ 00-7/28 G03B 9/08-9/54

Claims (3)

(57) [Claims] 1. To obtain a control start signal of an exposure control circuit
In the photo sensor, the light receiving section receives the reflected light of the light emitted from the light emitting section to the traveling area of the shutter blade, and the relative position of the light emitting section and the light receiving section of the photo sensor changes the light emitting section. Area of exit surface and entrance surface of the light receiving part
And a means for moving the photo sensor in a direction substantially parallel to the traveling surface of the shutter blades with respect to the shutter base plate, the shutter base plate having a hole for adjusting the intensity of light at the light receiving portion. And a trigger detection level adjusting mechanism for a camera lens shutter. 2. A means capable of moving the photosensor in the parallel direction with respect to the shutter base plate is provided on the shutter base plate so as to guide the photosensor so as to be movable in predetermined forward and reverse directions. A guide portion formed, an adjustment shaft pivotally attached to the shutter base plate and having an eccentric shaft portion, a photosensor is movably provided while being carried, and a longitudinal direction in a direction intersecting the forward and reverse directions. 2. The trigger detection level adjusting mechanism for a lens shutter according to claim 1, further comprising: a substrate having elongated holes that are formed so as to coincide with each other and that are fitted to the eccentric shaft portion. 3. The trigger level adjusting mechanism for a lens shutter according to claim 2, wherein the forward and reverse directions are tangential directions of the exposure aperture.