JPH04281684A - Exposure device - Google Patents

Abstract

PURPOSE:To obtain a slow shutter speed and a fast shutter speed by a single exposure method. CONSTITUTION:With a mechanical shutter drive motor (a) energized, a mechanical shutter (c) starts closing when a prescribed time T3 required for a prescribed mechanical operation elapses from the point of time, and after the mechanical shutter drive motor is energized, a trigger pulse (b) is outputted, and when an exposure control time T1 calculated by a photometry circuit elapses from the point of time, a CCD electronic shutter (d) is opened in this timing, a region shown in hatched lines indicates am effective exposure quantity and when the exposure control time T1 is 0 sec, the shutter speed is slowest and as the exposure time T1 gets larger, the shutter speed gradually gets faster and the end period of the exposure control time T1 takes a point of time after the point time when the mechanical shutter starts closing.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus for an electronic still camera.

0002

2. Description of the Related Art An exposure device for an electronic still camera equipped with a CCD image pickup device, etc. is equipped with a CCD electronic shutter and a mechanical shutter. The time until it closes is the exposure time.

FIG. 3 shows an exposure time chart of such a conventional exposure apparatus. With this exposure equipment,
Typically, the mechanical shutter (FIG. 3c) is opened and the CCD electronic shutter (FIG. 3d) is closed. When the shutter button is pressed, an exposure control time T1 is calculated by a photometry circuit built into the electronic still camera, and a trigger pulse (FIG. 3a) is then output. When the trigger pulse is output, the CCD electronic shutter (FIG. 3d) is opened at this timing. When the exposure control time T1 calculated by the photometry circuit has elapsed since the trigger pulse was output, the mechanical shutter actuator (Fig. 3b) is turned on at this timing, and when the mechanical operation delay time T2 has elapsed from this point, Mechanical shutter (Figure 3c)
begins to close. As shown by diagonal lines in FIG. 3, the range in which both the mechanical shutter (FIG. 3c) and the CCD electronic shutter (FIG. 3d) are open becomes the effective exposure amount (effective exposure time). By the way, in this exposure apparatus, the mechanical shutter (Fig. 3c) starts to close when the mechanical operation delay time T2 has elapsed from the time when the mechanical shutter actuator (Fig. 3b) is turned on, so the exposure control Even if the time T1 is 0 seconds, a mechanical operation delay time T2 is required from the time the mechanical shutter actuator (Fig. 3b) is turned on until the mechanical shutter (Fig. 3c) begins to close. Assuming that the operation delay time T2 is 2 msec, 1/500 sec
Therefore, it is not possible to obtain a shutter speed faster than .

FIG. 4 shows that the mechanical operation delay time T2 is 2 mse.
This figure shows an exposure time chart of a conventional exposure apparatus that can obtain a shutter speed faster than 1/500 sec even if the shutter speed is 1/500 sec. Even with this exposure equipment,
The mechanical shutter (FIG. 4c) is opened and the CCD electronic shutter (FIG. 4d) is closed. When the shutter button is pressed, an exposure control time T1 is calculated by a photometry circuit built into the electronic still camera, and a trigger pulse (FIG. 4a) is then output. When the trigger pulse is output, the mechanical shutter actuator (Fig. 4b) is turned on at this timing, and when the mechanical operation delay time T2 has elapsed from this point, the mechanical shutter (Fig. 4b) is turned on.
c) begins to close. On the other hand, when the exposure control time T1 calculated by the photometry circuit has elapsed since the trigger pulse was output, the CCD electronic shutter (Fig. 4d
) will be opened. As shown by diagonal lines in FIG. 4, the range in which both the mechanical shutter (FIG. 4c) and the CCD electronic shutter (FIG. 4d) are open becomes the effective exposure amount (effective exposure time). In this way, in this exposure apparatus, the mechanical shutter actuator (FIG. 4b) is turned on at the time the trigger pulse (FIG. 4a) is output, so the effective exposure time can be kept below the mechanical operation delay time T2. Therefore, even if the mechanical operation delay time T2 is 2 msec, a shutter speed faster than 1/500 sec can be obtained. However, in this exposure apparatus, since the mechanical shutter actuator (FIG. 4b) is turned on at the time when the trigger pulse (FIG. 4a) is output, the effective exposure time cannot be made longer than the mechanical operation delay time T2. Mechanical operation delay time T2 is 2mse
c, it means that it is not possible to obtain a shutter speed slower than 1/500 sec.

Conventionally, the exposure method shown in FIG. 3 and the exposure method shown in FIG. 4 are used together, and when the shutter speed is slow, the exposure method is switched to the one shown in FIG. If the exposure method is fast, the exposure method is switched to the one shown in FIG.

[0006]

[Problems to be Solved by the Invention] However, in such a conventional exposure apparatus, the shutter speed at which the exposure method is to be changed is longer than the mechanical operation delay time T2 (for example, 2 msec).
Since the range is extremely narrow within the range c), it is necessary to switch to the exposure method shown in Figure 3 in order to slow down the shutter speed, for example, due to the delicate individual operating errors of each component. Nevertheless, the exposure method as shown in Figure 4 may remain the same, making switching the exposure method unstable and causing a large error in the effective exposure amount before and after the shutter speed at which the exposure method should be switched. There was a problem that it could happen. SUMMARY OF THE INVENTION An object of the present invention is to provide an exposure apparatus that can obtain both slow and fast shutter speeds, regardless of conventional mechanical operation delay times and without switching exposure methods.

[0007]

[Means for Solving the Problems] The present invention provides an exposure apparatus in which the exposure time is the time from when the electronic shutter opens to when the mechanical shutter closes while the mechanical shutter is open. , a mechanical shutter closing means that starts closing the mechanical shutter after a certain mechanical operation when turned on, and a trigger that is triggered at the time the mechanical shutter closing means is turned on or before the mechanical shutter starts closing after being turned on. A trigger pulse output means for outputting a pulse, and an electronic shutter opening means for opening an electronic shutter when a certain exposure control time calculated by a photometric circuit has elapsed from the time when the trigger pulse output means outputs a trigger pulse. It was designed to do so.

[0008]

[Operation] According to the present invention, when the mechanical shutter closing means is turned on, the mechanical shutter begins to close after a certain period of time required for a certain mechanical operation has elapsed from this point on.
On the other hand, the trigger pulse output means outputs a trigger pulse when the mechanical shutter closing means is turned on or after turning on and before the mechanical shutter starts to close, and from the time when this trigger pulse is output, the photometry circuit calculates the When a certain exposure control time has passed, the electronic shutter will be opened at this timing, so the exposure control time will be 0s.
ec, the shutter speed is the slowest, and as the exposure control time increases, the shutter speed gradually becomes faster, and the end of the exposure control time can be set at a time later than the time when the mechanical shutter begins to close. Therefore, both slow and fast shutter speeds can be obtained regardless of the mechanical operation delay time and without switching the exposure method as in the prior art.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the main parts of an exposure apparatus according to an embodiment of the present invention.

This exposure apparatus is equipped with a motor 1 that serves as an actuator for opening and closing shutter blades of a mechanical shutter (not shown). A small gear 3 is attached to the output shaft 2 of the motor 1. A large gear 5 of a two-stage reduction gear 4 is meshed with the small gear 3. A gear 8 provided on the lower surface of a cam 7 is meshed with the small gear 6 of the reduction gear 4 . The cam 7 is rotatably provided around a shaft 9. A first cam surface 10 made of a circular arc surface centered on the shaft 9 is formed on approximately three-fourths of the outer circumference of the cam 7, and one end of the first cam surface 10 is formed on the remaining approximately one-fourth. A second cam surface 11 is formed as a curved surface whose diameter gradually decreases from the end, and a step surface 12 is formed between the other end of the first cam surface 10 and one end of the second cam surface 11. has been done. Furthermore, a protrusion 13 is provided at a predetermined location on the upper surface of the cam 7. A trigger switch 14 is provided at a predetermined location corresponding to the protrusion 13.
A pair of leaf spring contacts 15 and 16 are arranged. An opening/closing lever 17 for opening and closing shutter blades of the mechanical shutter is arranged at a predetermined location corresponding to the outer peripheral surface of the cam 7. The opening/closing lever 17 is rotatably provided around a shaft 18. The opening/closing lever 17 is a spring 1
A protrusion 20 normally provided at a predetermined location on the upper surface of the cam 7 is biased clockwise by the cam 7.
It is positioned at a position where it touches zero. In this state, the shutter blade of the mechanical shutter is open, and when the opening/closing lever 17 is rotated counterclockwise, the shutter blade of the mechanical shutter is closed. In addition,
A CCD electronic shutter (not shown) is placed at a position where it is exposed to light when the shutter blades of the mechanical shutter are opened.

Next, the exposure operation of this exposure apparatus will be explained in conjunction with the exposure time chart shown in FIG. In this exposure apparatus, the shutter blades of the mechanical shutter (Fig. 2c
) is opened and the CCD electronic shutter (Fig. 2d) is closed. Then, when the shutter button is pressed, the exposure control time T1 is calculated by the photometry circuit built into the electronic still camera, and the motor 1 (FIG. 2a) is turned on and begins to drive. When the motor 1 is driven, the cam 7 begins to rotate clockwise in FIG. When the cam 7 rotates clockwise, the protrusion 13 of the cam 7 first comes into contact with one leaf spring contact 15 of the trigger switch 14, and as a result, one leaf spring contact 15 is elastically deformed and contacts the other leaf spring contact 16. Upon contact, the trigger switch 14 is turned on and a trigger pulse (FIG. 2b) is output. When the exposure control time T1 calculated by the photometric circuit has elapsed since the trigger pulse was output, the CCD electronic shutter (FIG. 2d) is opened at this timing. The cam 7 further rotates clockwise, and the stepped surface 12 of the cam 7 touches the protrusion 2 of the opening/closing lever 17.
0, the opening/closing lever 17 is rotated clockwise by the force of the spring 19, and its projection 20 is rotated clockwise by the force of the spring 19.
is the second cam surface 11 near the step surface 12 of the cam 7
comes into contact with. Then, as the opening/closing lever 17 rotates clockwise, the shutter blade (FIG. 2c) of the mechanical shutter closes. As shown by diagonal lines in FIG. 2, the range in which both the shutter blades of the mechanical shutter (FIG. 2c) and the CCD electronic shutter (FIG. 2d) are open becomes the effective exposure amount (effective exposure time). When the cam 7 further rotates clockwise, the protrusion 20 of the opening/closing lever 17 slides relatively on the second cam surface 11 of the cam 7 and then comes into contact with the first cam surface 10, so that the opening/closing lever 17 It is rotated counterclockwise against the force of the spring 19. Then, as the opening/closing lever 17 rotates counterclockwise, the shutter blade (FIG. 2c) of the mechanical shutter closes. Then, in the initial state shown in FIG. 1, the motor 1 stops. Possible methods of stopping the motor 1 include a method of stopping the motor 1 after a preset time has elapsed from the time when the trigger pulse (FIG. 2b) is output, or a method of using a stop position detection switch. The CCD electronic shutter (FIG. 2d) closes when a preset time has elapsed from the time when the shutter blades of the mechanical shutter (FIG. 2c) begin to close.

By the way, in this exposure apparatus, the motor 1 (
The time T3 from the time when the shutter blade (FIG. 2c) of the mechanical shutter starts to close from the time when the shutter blade (FIG. 2a) is turned on and begins to drive is mainly due to the step surface 12 of the cam 7 in the initial state shown in FIG. is determined by the relative positional relationship between and the protrusion 20 of the opening/closing lever 17 and the rotational speed of the cam 7,
Not only is it unrelated to the mechanical operation delay time T2 as shown in FIGS. 3 and 4, but it is also considerably longer (for example, 1 sec) than the mechanical operation delay time T2 (for example, 2 msec). The effective exposure time is longest when the exposure control time T1 is 0 sec, and becomes gradually shorter as the exposure control time T1 increases. Therefore, the shutter speed is set so that the exposure control time T1 is 0 sec.
The closer the exposure control time T1 is to the point where the shutter blades of the mechanical shutter (FIG. 2c) are completely closed, the faster the exposure control time T1 is. In this way, in this exposure apparatus, the shutter speed is the slowest when the exposure control time T1 is 0 sec, and as the exposure control time T1 increases, the shutter speed gradually becomes faster.
1 can be set at a later point in time than the shutter blade of the mechanical shutter (FIG. 2c) begins to close, and therefore, regardless of the conventional mechanical operation delay time T2, and by changing the exposure method. Both slow and fast shutter speeds can be obtained without switching, thereby making it possible to stabilize the effective exposure amount especially at fast shutter speeds.

Note that in this exposure apparatus, the exposure control time T
When 1 is 0 sec, the shutter speed is the slowest, but
If you want to make it slower than this, the motor 1 can be temporarily turned off after the trigger switch 14 is turned on and the trigger pulse (Fig. 2b) is generated, until the shutter blades of the mechanical shutter (Fig. 2c) begin to close. It may also be possible to incorporate a sequence such as stopping the process automatically. In this case, the shutter speed is slowed down to, for example, 1 second or more, so there is a considerable amount of time to spare.Therefore, there are subtle operating errors in each component, and even if the switching of the exposure method becomes unstable. However, the error in effective exposure amount can be almost ignored.

Further, as an actuator for opening and closing the shutter blade of the mechanical shutter, an actuator capable of pulse control such as a step motor may be used. When using an actuator capable of pulse control, instead of using the trigger switch 14 in the above embodiment, the trigger pulse is generated by a pulse applied at the time the actuator is turned on or after the actuator is turned on. Good too. Furthermore, if the shutter speed is desired to be slower than the shutter speed when the exposure control time T1 is 0 sec, this can be achieved by changing the width of the pulse applied to the actuator as necessary.

[0015]

As explained above, according to the present invention, when the mechanical shutter closing means is turned on, the mechanical shutter closes when a certain period of time required for a certain mechanical operation has elapsed from this point on. On the other hand, the trigger pulse output means outputs a trigger pulse when the mechanical shutter closing means is turned on or after the mechanical shutter starts to close, and from the moment this trigger pulse is output, the photometry circuit Since the electronic shutter is opened at this timing when a certain exposure control time calculated by has elapsed, the shutter speed is the slowest when the exposure control time is 0 seconds, and the shutter speed increases as the exposure control time increases. It gradually becomes faster, and the end of the exposure control time can also be set to a point later than the time when the mechanical shutter begins to close. Therefore, the exposure method can be switched without regard to the conventional mechanical operation delay time. without any
Both slow and fast shutter speeds can be obtained, and thus the effective exposure amount can be stabilized especially at fast shutter speeds.

[Brief explanation of the drawing]

FIG. 1 is a plan view of essential parts of an exposure apparatus in an embodiment of the present invention.

FIG. 2 is an exposure time chart of this exposure apparatus.

FIG. 3 is an exposure time chart when the shutter speed of a conventional exposure apparatus is slow.

FIG. 4 is an exposure time chart when the shutter speed of a conventional exposure apparatus is fast.

[Explanation of symbols]

1 Motor 7 Cam 14 Trigger switch 17 Opening/closing lever

Claims (2)

[Claims] 1. An exposure apparatus in which the exposure time is the time from when an electronic shutter opens with a mechanical shutter open to when the mechanical shutter closes, and when turned on, a certain mechanical Mechanical shutter closing means that starts closing the mechanical shutter after the operation, and a trigger that outputs a trigger pulse when the mechanical shutter closing means is turned on or after turning on and before the mechanical shutter starts closing. It comprises a pulse output means, and an electronic shutter opening means that opens the electronic shutter when a certain exposure control time calculated by a photometric circuit has elapsed from the time when the trigger pulse output means outputs the trigger pulse. Exposure equipment. 2. The mechanical shutter closing means includes an actuator, a cam rotated in one direction by the actuator, and a cam that rotates in the forward direction as the cam rotates in one direction and then rotates in the opposite direction. 2. The mechanical shutter according to claim 1, further comprising an opening/closing lever that closes the mechanical shutter when the mechanical shutter is rotated in the forward direction and opens the mechanical shutter when the mechanical shutter is rotated in the reverse direction. exposure equipment.