JPH04172877A - Electronic still camera - Google Patents

Abstract

PURPOSE:To eliminate the problem of finder parallax from the title camera by providing a holder fitted with a relay lens and image sensor between an image pickup lens and eyepiece along a plane perpendicular to the optical axis and alternatively positioning the relay lens and image sensor on the optical axis. CONSTITUTION:When each section of this electronic still camera is initialized by turning on a power supply switch which is not shown in the figure, a holder 8 is set to an observing position and a relay lens 7 is positioned between an image pickup lens 3 and eyepiece 4. Such state is monitored by discriminating whether or not the rotated position of a stepping motor 14 is at its initial position. Since the image picked up by the lens 3 can be observed through the eyepiece 4, the image of an object can be observed in a state where no influence is received from finder parallux. When a release button 15 is pressed thereafter, the holder 8 is lowered to an image pickup position and the lens 7 is retreated from the optical axis 5. Then the image sensor 5 is positioned on the optical axis 5 in place of the lens 7 so that an optical image can be taken.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a low-cost electronic still camera that is free from finder balax.

[Conventional technology]

Commercial electronic still cameras use TTL finders that use reflex mirrors and beam splitters. However, electronic still cameras that use TTL viewfinders tend to be expensive, and the cameras themselves are large, so it is currently difficult to use them in popular -g electronic still cameras. . For this reason, popular models are equipped with a finder lens separate from the imaging lens.

[Problem to be solved by the invention]

Electronic still cameras use solid-state image sensors (area-type image sensors) that utilize COD, etc., as image sensors;
As the light sensitivity of 2018 has improved considerably, even a relatively dark lens (with a large F number) is now sufficient as an imaging lens. As the F number of the imaging lens becomes smaller and the depth of focus becomes deeper, the range that can be imaged also expands to the short distance side. Considering these circumstances, it has become desirable to eliminate finder balax even in popular electronic still cameras.

[Purpose of the invention]

The present invention has been made in consideration of the above background, and an object of the present invention is to provide a low-cost electronic still camera that eliminates finder balax without hindering the miniaturization of electronic still cameras.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a holder that is movable along a plane perpendicular to the optical axis between an imaging lens and an eyepiece lens, and also attaches a relay lens and an image sensor to this holder. , the relay lens and the image sensor are alternatively arranged on the optical axis by moving the holder.

[Effect]

According to the above configuration, a TTL finder is constructed by moving the holder and arranging the relay lens on the optical axis, and it is possible to capture the subject and determine the composition without finder balax. Also,
During imaging, the image sensor is moved onto the optical axis instead of the relay lens by the movement of the holder, so that the object image observed through the finder can be directly captured. Hereinafter, the present invention will be explained according to the illustrated embodiments.

【Example】

In FIG. 1, which schematically shows a cross section of essential parts of an electronic still camera using the present invention, an imaging lens 3 is attached to the front of a camera body 2, and an eyepiece lens 4 is attached to the back. By using a well-known autofocus mechanism, it is also possible to automatically move the imaging lens 3 along the optical axis 5 and perform focusing. A holder 8 holding an image sensor 6 and a relay lens 7 is provided between the imaging lens 3 and the eyepiece lens 4. The image sensor 6 converts an optical image formed on its photocathode by the imaging lens 3 into an electrical signal and outputs the electrical signal. Further, the relay lens 7 functions to relay the image formed by the imaging lens 3 to the eyepiece lens 4. The camera body 2 includes a signal processing circuit that converts the electrical signal from the image sensor 6 into a video signal, and a recording device that writes the video signal from the signal processing circuit onto a medium such as a still video floppy or an IC memory card. Although it is built in, it is not directly related to the present invention and is therefore not shown. A guide arm 10 is integrally formed on the holder 8,
A pair of guide bars 11 fixed to the camera body 2 are inserted into the pair of guide holes formed in the guide arm 10. II is fitted. Further, a rack gear 10a is formed on the guide arm 10, and a pinion 13 is meshed with this rack gear 10a. When the pinion 13 is driven by the stepping motor 14, the holder 8 can be moved along a plane perpendicular to the optical axis 5. The operation of the electronic still camera described above will be explained below. By turning on a power switch (not shown), each part of the electronic still camera is set to its initial state. In this initial state, the holder 8 is placed at the observation position as shown in FIG. 1, and the relay lens 7 is positioned between the imaging lens 3 and the eyepiece lens 4. The position of the relay lens 7 in this initial state can be monitored by checking whether the rotational position of the stepping motor 14 is at the initial position. When the relay lens 7 is positioned behind the imaging lens 3 as shown in Fig. 1, the image obtained by the imaging lens 3 is observed through the eyepiece 4, so the subject image can be observed without finder balax. can do. When the release button 15 is pressed, the stepping motor 14 momentarily rotates by a certain amount, lowering the holder 8 to the imaging position shown in FIG. 2 via the pinion 13 and rack gear 10a. As a result, the relay lens 7 is retracted from the optical axis 5, and the image sensor 6 is positioned on the optical axis 5 instead. When the stepping motor 14 rotates by the predetermined amount, a drive signal is supplied to the image sensor 6, and the optical image taken by the imaging lens 3 is captured by the image sensor 6. The electrical signal obtained as a result of this imaging is transferred to a signal processing circuit, which performs well-known signal processing. The recording process causes the video signal to be written to the recording medium. When one screen is captured by the image sensor 6,
The stepping motor 14 reverses, and the holder 8 returns to the first position.
The camera returns to the observation position shown in the figure, thereby completing one imaging sequence. In the case of the above embodiment, since the holder 8 is moved up and down along a plane perpendicular to the optical axis 5, the thickness of the camera body 2 tends to increase. To solve this problem, in addition to having the holder 8 slide laterally, it is also possible to use a rotating holder as shown in FIG. 3, for example. In FIG. 3, the holder 20 is connected to a stepping motor 21.
It is fixed perpendicularly to the axis 22 of. The axis 22 is parallel to the optical axis 5, so when the stepping motor 21 is driven, the holder 20 rotates along a plane perpendicular to the optical axis 5. The relay lens 7 is attached to the holder 20.
Since the image sensor 6 is fixed, either the relay lens 7 or the image sensor 6 can be positioned on the optical axis 5 by drive control of the stepping motor 21. Although the above has been explained according to the illustrated embodiment, it is not necessarily necessary to use a stepping motor to move the holder along a plane perpendicular to the optical axis; for example, an electromagnetic drive device such as a solenoid may be used. It is possible.

【Effect of the invention】

As explained above, the electronic still camera of the present invention has a relay lens and an image sensor behind the imaging lens.
When the relay lens is placed on the optical axis, the image sensor, relay lens, and eyepiece constitute a finder optical system. Since it is positioned behind the camera, it is possible to observe the subject image without viewfinder parallax. In addition, the body size of the camera is different from that of conventional TT cameras using reflex mirrors and beam splitters.
Compared to L-finder type electronic still cameras, it is easier to make smaller and the cost burden is lower.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts of an electronic still camera using the present invention in a viewfinder observation state. FIG. 2 is a sectional view of a main part of the electronic still camera shown in FIG. 1 in an imaging state. FIG. 3 is a front view showing another example of the holder portion used in the electronic still camera of the present invention. 3...Imaging lens 4...Eyepiece lens 6...Image sensor 7...Relay lens 8.20...Holder 14.21...Stepping motor. Figure 1 Figure 2 cl

Claims (1)

[Claims] (1) A holder that is movable along a plane perpendicular to the optical axis between the imaging lens and the eyepiece, a relay lens and an image sensor held in this holder, and the relay lens is inserted on the optical axis. An electronic still camera comprising: a holder moving mechanism that selectively moves the holder between an observation position and an imaging position where the image sensor is inserted on an optical axis.