JP2936621B2 - Electronic still camera - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic still camera, and more specifically, to an electronic still camera that records a captured image on a rotating recording medium.

[Prior art] A still camera that records a still image captured by a solid-state imaging device such as a CCD on a recording medium such as a magnetic disk,
A so-called electronic still camera has been proposed, in which a still image recorded on the magnetic disk is reproduced and displayed on a monitor device or printed on paper by a printer.

Such an electronic still camera does not require chemical processing such as development compared to a conventional still camera using a silver halide film, and the captured image can be immediately confirmed on a monitor device or a hard copy. It also has the advantage that it can be transmitted to remote locations.

[Problems to be Solved by the Invention] However, an electronic still camera consumes a large amount of power for rotating a magnetic disk as a recording medium and driving an image sensor. Further, when a focal length adjusting mechanism for electrically adjusting the focal length of the photographing optical system is incorporated, much power is consumed for adjusting the focal length.

As described above, when there are a plurality of circuits that consume a large amount of power during operation, it is theoretically sufficient to prepare a battery having a sufficiently large capacity. However, in practice, there is a limit in battery capacity and battery accommodation space.

Further, when the driving of the image sensor and the above-mentioned focal length adjustment are performed at the same time, there is a problem that the output video signal of the image sensor is disturbed due to a decrease in power supply voltage.

Therefore, an object of the present invention is to provide an electronic still camera that solves such a problem.

[Means for Solving the Problems] An electronic still camera according to the present invention includes an imaging optical system having a variable focal length, imaging means for converting an optical image by the imaging optical system into an electric signal, and imaging by the imaging means. Recording means for recording an image on a recording medium, focal length adjusting means for adjusting the focal length of the photographing optical system by electrical driving, a first release switch for starting driving of the imaging means, and recording A second release switch for starting the recording operation by the means, and the first release switch.
And a first release switch, which is provided separately from the second release switch, and which is manually operated to start a focal length adjustment operation by the focal length adjustment means by the focal length adjusting means, and the first release switch. Thus, after the driving of the imaging unit is started, until the operation of the first release switch is stopped, the focal length adjusting operation by the focal length adjusting unit can be performed by manually operating the focal length adjusting operation member. Control means for prohibiting the start.

[Operation] The operation of adjusting the focal length of the photographing optical system by the focal length adjusting means consumes a large amount of power at a time and temporarily lowers the power supply voltage. The decrease in the power supply voltage makes the operation of the imaging unit unstable, and causes disturbance in the output video signal. By the above means, the focal length adjustment operation and the driving of the imaging means are not performed simultaneously, and the imaging means always operates stably.
Therefore, a good video signal without disturbance can be obtained from the imaging means. Further, by not operating the imaging means and the focal length adjusting means at the same time, it is not necessary to prepare a power supply having an unnecessarily large capacity.

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

FIG. 1 is a schematic block diagram of an embodiment of the present invention. 10a is a focusing lens, 10b and 10c are focal length adjusting lenses, and 10d is a fixed lens, which constitute a photographic optical system. Reference numeral 12 denotes a focusing lens holding frame that holds the focusing lens 10a, and includes a gear portion 12a and a screw portion 12b. 14,1
Reference numeral 6 denotes a lens holding frame for holding the focal length adjusting lenses 10b and 10c. Reference numeral 18 denotes a cam cylinder having a cam groove for determining the positions of the lens holding frames 14 and 16 in the optical axis direction, and is rotatably held by a fixed portion 20 of the camera. 22, 24 are rollers fixed to the lens holding frames 14, 16, pass through the cam groove of the cam cylinder 18, fit into the long groove 20a in the optical axis direction of the camera fixing part,
The lens holding frames 14, 16 are positioned. In addition, cam cylinder 1
When 8 rotates, the lens holding frames 14 and 16 move in the optical axis direction due to the cam grooves.

26 is an aperture and 27 is a shutter. Reference numeral 28 denotes a finder optical system, and lenses 28a and 28 fixed to the fixed portion 20 of the camera.
c, and a lens 28b movably held along the optical axis of the lenses 28a, 28c. An image sensor 30 converts an optical image into an electric signal.

Reference numeral 32 denotes a focus motor for rotating the focusing lens frame 12, and the number of rotations is detected by an encoder 32a. The gear 32b of the motor 32 meshes with the gear portion 12a of the focusing lens frame 12. Since the screw portion 12b of the focusing lens holding frame 12 is engaged with the screw portion 20b of the fixing portion 20 of the camera, the rotation of the motor 32 moves the focusing lens holding frame 12 in the optical axis direction.

34 is a zoom motor whose rotation speed is
Detected by 34a. The gear 34b of the motor 34 meshes with the gear 18a of the cam barrel 18. When the zoom motor 34 rotates, the cam cylinder 18 rotates about the optical axis of the photographing optical system by the gears 34b and 18a, and the focal length adjusting lenses 10b and 10c
Due to the lift of the cam groove, it moves in the optical axis direction together with the lens holding frames 14 and 16.

Reference numeral 36 denotes a finder motor, the rotation speed of which is detected by an encoder 36a. A screw 36b rotated by the motor 36 is engaged with a screw portion 38a of a lens holding frame 38 that holds the movable lens 28b, and the rotation of the motor 36 moves the lens holding frame 38, and thus the movable lens 28b, in the optical axis direction. It has become.

40 is a zoom button, 42 is a photometry circuit, 44 is a distance measurement circuit,
46 is a recording circuit for recording a captured image on a recording medium, 48 is a camera control circuit for controlling the whole, and 50 is a power supply composed of a battery. Reference numeral 52 denotes a display device (for example, a liquid crystal display device) that displays an operation state and the like. The camera control circuit 48
As shown in the figure, a so-called shutter control circuit, focus control circuit, aperture control circuit, zoom control circuit, image sensor control circuit, and the like are provided. In FIG. 2, reference numeral 54a denotes a release switch which is turned on when a shutter release button (not shown) is depressed by a half stroke, and 54b.
Is a release switch that is turned on at the further depressed position. Reference numeral 40a denotes a zoom switch for instructing zooming to the telephoto side, and reference numeral 40b denotes a zoom switch for instructing zooming to the wide side.

Next, the operation will be described with reference to FIG. When a power switch (not shown) is operated to turn on the power, the camera control circuit 48 first sets the aperture 26 to the open state,
Is closed, and the focusing lens 10a is moved to a position for focusing on infinity (S1). In this state, the photographer determines the composition. That is, while looking through the viewfinder, the zoom button
Press one of the 40 switches 40a, 40b. When the switch 40a is pressed (S2), the motors 34 and 36 rotate forward, and the photographing optical system and the finder optical system are adjusted to the telephoto side (S3).
When 40b is pressed (S4), the motors 34 and 36 are reversed, and the photographing optical system and the finder optical system are adjusted to the wide image side (S5).

After the composition is determined in this way, the photographer presses a release button (not shown). When the release switch 54a is turned on when the release button is pressed half a stroke (S6), the camera control circuit 48 measures the brightness of the subject by the photometry circuit 42, and measures the distance to the subject by the distance measurement circuit 44. And adjust the white balance (S7). After that, the driving of the image sensor 30 is started (S8). The aperture value and the shutter speed are determined based on the photometric information, the amount of movement of the focusing lens 10a is determined based on the distance measurement information (S9), and the focusing lens 10a is moved to the determined position by the motor 32 (S10).

After S10, while the release switch 54a is on, it waits for the release switch to be further depressed and the release switch 54b to be turned on (S11, 12). When the release switch 54a is turned off (S12), which means that no image is captured, the focusing lens 10a is moved to a predetermined standby position (infinity in-focus position), and the driving of the image sensor 30 is stopped. (S13) Return to S2. When the release switch 54b is turned on, a shooting operation is started. That is, the diaphragm 26 is driven to have the aperture value determined in S9 (S14), and the shutter 27 is opened for the determined shutter time (S15). The charge stored in the image sensor 30 is read out by opening and closing the shutter 27 and transferred to the recording circuit 46 (S16), and the captured image is recorded in the unrecorded area of the rotating recording medium (S17).

Thereafter, if the release switch 54b remains on, the photographing and recording (S15 to 17) are repeated (S18). Even if the switch 54b is turned off, if the switch 54a remains on (S19), the focusing lens 10a is stopped at that position, and the imaging element 30 is kept in a driven state.
Wait for 54b to turn on (S19). When the switch 54a is turned off, the aperture 26 is opened (S20), the focusing lens 10a is moved to a predetermined standby position (infinity in-focus position), and the image pickup device
Driving 30 is stopped (S13), and the shooting ends.

In this embodiment, the zoom button 40 (switches 40a, 40
When the drive of the image sensor 30 is started while the focal lengths of the photographing optical system and the finder optical system are adjusted according to b), the focus adjustment operation is stopped. Also, the image sensor 30
If the zoom button 40 is pressed during the driving of the camera, if the captured video is being recorded, after the recording is completed, the driving of the image sensor is stopped and the optical system movement for adjusting the focal length starts, If the captured video is not being recorded, the driving of the image sensor is immediately stopped and the optical system is moved for adjusting the focal length. Of course, the imaging device 30 is driven during the shooting and recording operation.

It goes without saying that the recording medium for the captured image may be a solid-state memory such as a semiconductor memory.

In the above embodiment, a zoom lens capable of continuously changing the focal length is used. However, the same applies to a lens capable of selecting, for example, bifocal or multifocal. It goes without saying that the lens (group) that moves for focusing is not limited to the illustrated example. When a lens (group) for adjusting the focal length (hereinafter referred to as a variable power lens group) is also used as a focusing lens, each of the variable power lens groups is moved independently in the optical axis direction. It is necessary that the movement can be controlled individually. A mechanism for this is described, for example, in U.S. Pat.
It is described in No. 1.

[Effects of the Invention] As can be easily understood from the above description, according to the present invention, since the driving of the imaging element and the focal length adjustment of the imaging optical system are not performed at the same time, the power supply voltage fluctuation due to the focal length adjustment is reduced. The operation of the image sensor is not adversely affected, and a good video signal can be obtained. In addition, the power supply in the camera can be used efficiently.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a block diagram of the camera control circuit 48 and its peripheral circuits in FIG. 1, and FIG. 3 is an operation flowchart of FIG. 10a: Focusing lens, 10b, 10c: Focal length adjustment lens, 10
d: Fixed lens, 12: Focusing lens holding frame, 12a: Gear part, 12
b: screw part, 14, 16: lens holding frame, 18: cam cylinder, 18a: gear part, 20: camera fixing part, 20a: long groove part, 20b: screw part, 22,
24: roller, 26: aperture, 27: shutter, 28: finder optical system, 28a, 28c: lens, 28b: movable lens, 30: image sensor, 3
2: Focus motor, 32a, 34a, 36a: Encoder, 32b,
34b: gear, 34: zoom motor, 36: finder motor, 36b: screw, 38: lens holding frame, 38a: screw part, 40: zoom button, 40a, 40b: zoom switch, 54a, 54b: release ·switch

Claims (2)

(57) [Claims] 1. An imaging optical system having a variable focal length, imaging means for converting an optical image from the imaging optical system into an electric signal, recording means for recording an image captured by the imaging means on a recording medium, and the imaging optical system Focal length adjusting means for adjusting the focal length of the system by electrical driving, a first release switch for starting the driving of the imaging means, and a second release switch for starting a recording operation by the recording means. A release switch; a focal length adjusting operation member provided separately from the first and second release switches, for manually starting a focal length adjusting operation by the focal length adjusting means; After the driving of the imaging unit is started by operating the first release switch, the operation of the first release switch is stopped until the operation of the first release switch is stopped. Control means for prohibiting the focal length adjusting means from starting the focal length adjusting operation even when the focal length adjusting operation member is manually operated. And a controller for manually operating the focal length adjusting operation member to perform the focal length adjusting operation by the focal length adjusting unit.
2. The electronic still camera according to claim 1, wherein even if the release switch is operated, the start of driving of the imaging unit is prohibited.