JPH0341425A - Camera system - Google Patents

Abstract

PURPOSE:To save power consumption at the time of driving by independently setting the drive/control of a focus lens in photographing and finder systems and driving/controlling only an object focus lens based on a signal from a focus detecting system. CONSTITUTION:When first-stage switching is detected by a release switch detecting circuit 28, a signal relating to a subject distance which is found by the control circuit unit 21 in the focus detecting system 103, is transmitted to only a driving means 22 in the finder system 102; consequently the focus lens 8 is driven. Then, when a release switch second-stage is detected, a signal relating to the subject distance from the control circuit unit 21 is transmitted to the driving means 25 in the photographing system 1; thereby the focus lens 1 is driven and controlled. After the focus lens 1 is driven to the prescribed position, a photosensitive surface 7 is exposed, and photographing is completed.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a camera system in which a finder system and a focus detection system are provided independently for a photographing system, and in particular, the present invention relates to a camera system in which a finder system and a focus detection system are provided independently for a photographing system. The present invention relates to a camera system suitable for photographic cameras, still video cameras, etc., in which a focus lens in a camera system and a focus lens in a photographic system are independently driven and controlled.

(Prior art) Conventionally, a finder system and a focus detection system are provided independently for the photographing system, and while observing the subject image with the finder system,
Various camera systems have been proposed in which the focus of a photographing system is adjusted based on an output signal from a focus detection system. In such a camera system, when the photographing system has a variable magnification means, the finder system is also provided with a variable magnification means, and the magnification is changed in conjunction with the variable magnification means of the photographing system. This ensures that the photographic screen photographed on the photosensitive surface and the subject image observed in the viewfinder field coincide.

In addition, in many cases in such camera systems,
In order to prevent the camera from becoming larger and more complex, the viewfinder system does not have a focus section, and the viewfinder image is focused at a fixed distance from the object.

Furthermore, many of the recent camera systems use a focus detection system, and drive and control the focus lens of the photographing system based on an output signal from the black spot detection system. This makes it easy to take quick and good photographs.

(Problem to be solved by the invention) On the other hand, the shooting screen of recent still video cameras is approximately 1/4 to 115.5 times smaller than that of 35mm film, and for this reason, the shooting system used in still video cameras is a lens system. The overall size can be easily reduced, and it has the feature that it can easily be made smaller while obtaining a high zoom ratio of 3 or more, for example.

At this time, with the increase in magnification of the photographing system, an optical system with a similarly high magnification is used for the finder system, but unless the finder system is equipped with the same focusing function as before, it is necessary to There was a problem in that the diopter change became too large, making it difficult to observe a good viewfinder image.

To solve this problem, there is a method of providing a diopter adjustment means in a part of the finder system, but this method is not very preferable in terms of simplicity and quick shooting performance.

Another possibility is to drive the focus lens of the finder system in conjunction with the focus lens of the photographing system, but this method requires a large drive source to drive both at the same time, and has problems such as slow drive speed. There was a point.

In a camera system in which a finder system and a focus detection system are independently provided for the photographing system, the present invention drives only the focus lens necessary for viewfinder observation and photographing operations based on, for example, an output signal from the focus detection system. control, save power consumption when driving,
The purpose of the present invention is to provide a camera system that can perform focus operations quickly.

(Means for Solving the Problems) The camera system of the present invention is a camera system in which a finder system and a focus detection system are each independently provided for a photographing system, and a focus lens of the photographing system and a focus detection system of the finder system are provided. Each lens is independently driven and controlled by a driving means, and the viewfinder is controlled based on the output signal from the focus detection system by the first stage switch operation of a two-stage release switch provided for the photographing system. The present invention is characterized in that the focus lens of the photographing system is driven and controlled based on the output signal from the black spot detection system by the second stage switch operation of the release switch.

In particular, the present invention is characterized in that the drive stop pitch of the focus lens of the finder system is made coarser than the drive start pitch of the focus lens of the photographing system.

(Embodiment) FIG. 1 is a schematic diagram of a main part of an optical system according to an embodiment of the present invention.

In the figure, 101 is a photographing system, and 102 is a finder system, which is a secondary imaging type real image finder system. 10
3 is a focus detection system. The finder thread 102 and the focus detection system 103 are each provided independently of the photographing system 101.

The photographing system 101 includes, in order from the object side, a focus lens 1, a variator 2 for variable magnification that moves linearly on the optical axis, a compensator 3 that moves non-linearly on the optical axis to correct image plane fluctuations due to variable magnification, an aperture 4, Relay lens 5 for fixed imaging during zooming
, optical members 6 such as a low-pass filter and an infrared cut filter, and a CCD sensor 7.

The variator 2 and the compensator 3 constitute a variable power means 104.

Reference numeral 25 denotes a driving means, which drives and controls the focus lens 1 based on an output signal from the focus detection system 103.

Reference numeral 27 denotes a pulse plate unit, which is movably provided on the focus lens l.

26 is a photo ink clubter and a pulse plate unit 2
The number of stripes in the black and white pattern No. 7 is detected, and the amount of extension (movement) of the focus lens I is detected from the signal at this time.

In this embodiment, the amount of movement of the focus lens 1 is controlled by the driving means 25 while a signal based on the pulse plate unit 27 is detected by the photointerrupter 26.

The finder system 102 includes, in order from the object side, a focus lens 8, a variator 9 for variable magnification that moves linearly on the optical axis, a compensator 0 that moves non-linearly on the optical axis to compensate for image plane fluctuations due to variable magnification, and a first placed near the focus plane 12,
A first field lens 11 that guides the light beam from the front lens group in a predetermined direction. A secondary imaging lens 13 re-images the first finder image on the first focus surface 12 onto the secondary focus surface 15 as a second finder image via the second field lens 4; It has an eyepiece lens 16 for observing a second finder image of soil.

The variator 9 and the rotor 10 constitute a variable magnification means +05.

Reference numeral 22 denotes a driving means that drives and controls the focus lens 8 based on an output signal from the focus detection system 103. 2
A pulse plate unit 4 is provided in conjunction with the focus lens 8.

23 is a photointerrupter and pulse plate unit 2
The number of stripes in the black and white pattern based on 4 is detected, and the amount of extension (movement) of the focus lens 8 is detected from the signal at this time.

In this embodiment, a focus lens 8 similar to the photographing system 101 is used.
The amount of feed is controlled by the drive means 24 while a signal based on the pulse plate unit 24 is detected by the photointerrupter 24.

The magnification change means 105 of the finder system 102 is the photographing system 101
The magnification changing means 104 and the magnification changing means 104 are interlocked with each other.

Focus lens 8 of finder system 102 and photographing system 1
The focus lenses l of No. 01 are driven independently of each other. The depth of focus of the finder system 102 is the same as that of the photographing system 101.
Since the distance is deeper than that of the focus lens in the finder system, the drive stop pitch of the focus lens in the finder system is set to be coarser than that in the shooting system.

The finder system 102 according to this embodiment includes a focus lens 8, a magnification variable means 105, and a first field lens 11.
A first finder image is formed at the first focus surface 12 through the secondary imaging lens 13 and the second field lens 14.
5 as an erect second finder image, and the second finder image is observed using the eyepiece lens 16.

The focus detection system 103 includes a pair of detection lenses 17a and 17b that form a subject image on a sensor surface (to be described later), a pair of mirrors 18a and 18b that reflect light beams from the detection lenses 17a and 17b, and a reflecting prism 19. , and a pair of line sensors 20a, 20b.

Note that 20c is a dead zone member that separates the 1 pair of line sensors 20a and 20b.

21 is a control circuit unit, which includes a line sensor 20a.
, 20b is used to determine the subject distance.

Focus detection by the focus detection system 103 of this embodiment is performed by the method proposed in, for example, Japanese Utility Model Application No. 59-161012. That is, the subject image is captured by l pairs of line sensors 2.
Two separated images are formed on planes 0a and 20b, and the relative positional relationship of the separated images is measured by the control circuit unit 21 to determine the object distance.

Reference numeral 28 denotes a shutter release switch detection circuit, which is configured to detect two-step switch operations related to photographing and transmit them to the control circuit unit 21.

Next, we will discuss the drive operation of the camera system of this example in the second section.
This will be explained using the flowchart shown in the figure.

First, when the release switch detection circuit 28 detects the first-stage switch operation for preparation for shooting, the focus detection system 1
The signal related to the object distance determined by the control circuit unit 21 of 03 is sent only to the drive means 22 of the finder system 102. Thereby, the driving means 22 controls the driving of the focus lens 8 by referring to the signal from the photointerrupter 23.

Next, when the second stage switch operation for photographing is detected by the release switch detection circuit 28, a signal regarding the object distance from the control circuit unit 21 is sent to the driving means 25 of the photographing system 101.

Thereby, the driving means 25 controls the driving of the focus lens 1 by referring to the signal from the photointerrupter 26. After the focus lens 1 is driven and controlled to a predetermined position, exposure 12 to the photosensitive surface 7 is performed, and photographing is completed.

As described above, the present embodiment is characterized in that the focus lenses of the photographing system 101 and the finder system 102 are set independently from each other, and only the target focus lens is driven and controlled by the signal from the focus detection system 103.

Generally, when the screen size of a still video camera is 1/2 inch, the diagonal length is 8 mm, and when the screen size is 2/3 inch, the diagonal length is 11 mm. For example, in a variable power system with a variable power ratio of 4, which uses a 1/2 inch CCD and includes a variable power range from standard to telephoto, the focal length is 9 to 36 mm, which is shorter than when using 35 mm film. For this reason, the imaging system can also be downsized.

Further, in an external finder system like this embodiment, the finder magnification is generally about 0.5 times at a standard angle of view. 2
The imaging magnification of the next imaging system is 1x, and the focal length of the eyepiece is 1
If it is 8 mm, the focal length of the objective system will be 9 to 36 mm, which is equivalent to the photographing system.

The shooting range of the shooting system is from 0.7m to infinity2, and the diopter of the finder system is on the telephoto side (close distance equivalent to 1 dayopter).
day focus amount).

In viewfinder systems, either the viewfinder field of view and the information display inside the viewfinder, including the field frame, are observed at the same time, or the information display is fixed at a constant diopter.

For this reason, it is better to have a smaller difference from the viewfinder field of view, and the viewfinder diopter will be blurry if it is less than the appropriate diopter.
After IJI'ip is applied, the deviation from the appropriate diopter needs to be, for example, about 0.5 to 1 diopter. If there are more than 10 changes in diopter, it is necessary to include a focus function in the viewfinder system.

In this embodiment, if a method is adopted in which the focus lens of the finder system is driven in conjunction with the focus lens of the photographing system in a camera system as described above, the finder system! Note: Every time you change the image, you have to move the focus lens, which is a relatively heavy camera, which increases the power consumption of the camera, and also makes the movement less smooth, which is not good, so as mentioned above, the viewfinder Only the focus lens of the camera system is moved independently of the focus lens of the photographic system at the first stage of the release switch.

Also, set the F number of the shooting system to F2.8, for example, and set the CCD
If the permissible circle of confusion of the photographing system is set to about 0.02 mm from the number of pixels, etc., the number of stop positions N of the focus lens of the photographing system is 700 0.02 x 2.828 x 2 = 16.4 (pieces). Based on this and the diopter change calculated above, the drive stop pitch of the finer type focus lens should be 5 to 6 points.

For this reason, for example, as described above, the drive stop+L pitch of the focus lens of the finder system is set to be coarser than that of the photographing system, so that quick drive control can be achieved.

In this embodiment, the amount of deviation in the finder diopter is proportional to the square of the focal length of the objective system, so on the wide-angle side, even if no focus operation is performed, the deviation in the finder diopter is small and does not pose a problem.

Therefore, in this embodiment, the focus lens of the finder system may be driven and controlled only within a predetermined zoom range on the telephoto side.

For example, if we allow the amount of change in the viewfinder diopter to be up to 2 day optics, the focal length will be 9 in the above-mentioned shooting system.
Since a good viewfinder image can be observed in the range of ~21 mm, the focus lens of the finder system may not be driven in this range.

(Effects of the Invention) According to the present invention, in a camera system in which a finder system and a focus detection system are independently provided for the photographing system, drive control of the focus lens of the finder system and the focus lens of the photographing system can be set independently. Based on the signal from the focus detection system, we have created a camera system that can save power consumption of the camera by controlling the drive of only the target focus lens as described above, and has a simplified focus mechanism. can be achieved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the main parts of an optical system according to an embodiment of the present invention, and FIG.
The figure is a flowchart of one embodiment of the present invention. In the figure, 101 is a photographing system, 102 is a finder system, 103 is a focus detection system, 104, lO5 is a variable magnification means, 1.8 is a focus lens, 2.9 is a variator, 3.10 is a compensator, 4 is an aperture, 5 is a relay lens, 7 is a CCD,
11.14 are first and second field lenses, 13 is a secondary imaging lens, 16 is an eyepiece, 23.26 is a photointerrupter, 224 and 27 are pulse plate units, 22
．． 25 is a driving means, 21 is a control circuit unit, 25 is a release switch 6, and b is a line sensor.

Claims (3)

[Claims] (1) In a camera system in which a finder system and a focus detection system are each provided independently for the photographing system, the focus lens of the photographing system and the focus lens of the finder system are independently driven and controlled by driving means. ,
The focus lens of the finder system is driven and controlled based on the output signal from the focus detection system by the first stage switch operation of a two-stage release switch provided for the photographing system, and the focus lens of the finder system is driven and controlled based on the output signal from the focus detection system. A camera system characterized in that a focus lens of the photographing system is drive-controlled based on an output signal from the focus detection system by a two-step switch operation. (2) The camera system according to claim 1, wherein the driving stop pitch of the focus lens of the finder system is made coarser than the driving stop pitch of the focus lens of the photographing system. (3) The photographing system and the finder system have variable magnification means that are linked to each other, and the focus lens of the finder system is used only in a zoom range on the telephoto side from the preset zoom position of the variable magnification means of the finder system. 2. The camera system according to claim 1, wherein the camera system is configured to drive and control.