JPH0722663Y2 - Single-lens reflex camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a single-lens reflex camera using a focusing screen having electrical connection, and more particularly to a single-lens reflex camera having a detachable focusing screen.

[Prior Art] A single-lens reflex camera is provided with a focusing screen for focusing a subject. Exchangeable and removable focusing screens are well known in single-lens reflex cameras. A single-lens reflex camera using these focusing screens can select an optimum screen according to various shooting conditions.

In addition, as described in Japanese Examined Patent Publication No. 61-60420, liquid crystal is used for the matte surface on which the image of the subject is formed and liquid crystal is also used for the display device that displays shooting information. Focusing screens with are known. In such a focusing screen, liquid crystal is electrically driven. When a voltage is applied to the liquid crystal, the directions of the liquid crystal molecules change, so that the light incident on the liquid crystal is scattered by the liquid crystal. As a result, a matte surface of liquid crystal is formed on the focusing screen, and light is scattered to form a subject image. Further, a liquid crystal is also used to display photographing information on the screen, and a voltage is applied to the liquid crystal to display information. The photographer observes this focusing screen and focuses on it. Further, when it is desired to transmit light as much as possible such as when a screen is dark due to a small amount of incident light from the photographing lens, the light is transmitted as much as possible by reducing scattering by the liquid crystal.

[Problems to be Solved by the Invention] A focusing screen of a type that is electrically driven according to shooting conditions must be externally applied with a voltage for driving a liquid crystal. For this reason, a large number of transparent electrodes are connected, which makes it difficult to attach and detach a focusing screen using liquid crystal.

Further, since various focusing screens are exchanged and electrically connected, the type of information displayed by each screen is often different, and therefore an appropriate voltage must be applied for each type of information.

The present invention has been made in view of the above problems, and an object thereof is to provide a single-lens reflex camera to which a focusing screen having an electrical connection can be attached and detached.

[Means for Solving the Problems] In this invention, in the single-lens reflex camera, the focusing screen is detachable from the camera body, and
The focusing screen and the camera body are provided with connection terminals that come into contact with each other when the focusing screen is mounted, and a drive voltage corresponding to the display mode of the screen is supplied from the camera body to the focusing screen through the connection terminals.

[Operation] In this single-lens reflex camera, the focusing screen is electrically connected to the camera body through the connection terminal, so that the focusing screen for performing an electrical display can be attached and detached. Further, since the type of the screen attached to the camera can be automatically determined, it is possible to apply a voltage for displaying according to the screen.

[Embodiment] FIG. 3 shows a schematic configuration of an optical system of a single lens reflex camera according to an embodiment of the present invention. A taking lens 2 is provided to form an image of light from the outside on a film surface (not shown). A reflecting mirror 4 is provided to reflect the light from the taking lens 2 toward the finder. The reflecting mirror 4 is lifted during photographing and the film is exposed by a shutter (not shown). A focusing screen 6 is provided to form an image of the light reflected by the reflection mirror 4. The focusing screen 6 is made of glass and has therein a liquid crystal 7 which is changed from a state of transmitting light to a state of diffusing light according to an applied voltage. This liquid crystal 7
A pentaprism 8 is provided to reflect the light from the focusing screen 6 having an angle of view toward the finder. A locking member 26 is fixed to the pender prism 8 with a screw as shown in FIG.
An eyepiece lens 10 is provided for focusing the light reflected by the pentaprism 8 and allowing the photographer to observe it.

Focusing screen 6 of one embodiment according to the present invention
Are shown in FIGS. 1 and 3. The focusing screen 6 has a liquid crystal 7 inside. The focusing screen 6 is provided with an electrode mounting portion 12 for supplying a voltage to be applied to the liquid crystal 7. The electrode mounting portion 12 is provided with a plurality of first transparent electrodes 13a. Further, three second transparent electrodes 13b are also provided in order to determine the type of the focusing screen 6. First
The number of transparent electrodes 13a can be changed depending on the type of focusing screen used. These first transparent electrodes
A conductive rubber 14 is provided to be in contact with the electrode mounting portion 12 having the 13a and the second transparent electrode 13b. The conductive rubber 14 has a plurality of first conductive portions 15a and second conductive portions 15b which are in contact with the first transparent electrode 13a and the second transparent electrode 13b, respectively.
Is provided. The number of the first conductive portions 15a corresponds to the maximum number of the first transparent electrodes included in various focusing screens. First conductive portion 15a and second conductive portion 1
A terminal plate 16 is attached to the conductive rubber 14 having 5b. The terminal board 16 has a first conductive portion 15 of a conductive rubber 14
A plurality of first terminals 17a and a plurality of second terminals 17b are provided corresponding to a and the second conductive portion 15b, respectively. The first terminal 17a and the second terminal 17b are made of copper foil.
Further, a screen holding frame 18 is provided to bring the electrode mounting portion 12 of the focusing screen 8 into contact with the conductive rubber 14. The screen holding frame 18 has a protrusion 20 and a hinge portion 22 protruding outward for fixing the focusing screen 6 in the camera. Further, the screen holding frame 18 is provided with a bottom portion 19 that is brought into close contact with the vicinity of the peripheral portion of the focusing screen 6.

The focusing screen 6 is attached to and detached from the camera body as follows. The focusing screen 6 is inserted so as to contact the bottom portion 19 of the screen holding frame 18. Screen holding frame with the focusing screen 6 inserted
18, a hinge portion 22 is engaged with a shaft 24 provided inside the camera body. Therefore, the screen holding frame 18 becomes rotatable around the shaft 24. When the screen holding frame 18 is rotated in the direction of arrow A, the electrode mounting portion 12 of the focusing screen 6 comes into contact with the conductive rubber 14 provided inside the camera.
Even after the electrode mounting portion 12 comes into contact with the conductive rubber 14, the screen holding frame 18 is further rotated, and the projection 20 comes into contact with the locking member 26 fixed to the pendant prism 8, so that the locking member 26 moves in the direction of arrow A. Is elastically deformed. When the screen holding frame 18 is further rotated, the projection 20 enters the locking hole 28 of the holding member 26, and the projection 20 is locked in the locking hole 28 of the locking member 26. In this locked state, the screen holding frame 18 is attached to the camera. In this state, the electrode mounting portion 12 of the focusing screen 6 is pressure-bonded to the conductive rubber 14. Therefore, the first terminal 17a and the second terminal 17b provided on the terminal plate 16 are connected to the first conductive portion 15
It is electrically connected to the first transparent electrode 13a and the second transparent electrode 13b via a and the second conductive portion 15b, respectively. When replacing with another focusing screen, the locking member 26, to which the projection 20 of the screen holding frame 18 is locked, is elastically deformed in the direction of arrow A to remove the projection 20 from the locking hole 28. Then, the screen holding frame 18 is removed from the camera body. After that, the focusing screen in the screen holding frame 18 is changed to another type, and the screen holding frame 18 is again locked to the camera body. In this way, the focusing screen can be replaced with various types.

An embodiment of the focusing screen used in this invention is shown in FIG. The focusing screen 6 is a screen mainly used for autofocus. The focusing screen 6 has a liquid crystal 7 inside, and the liquid crystal 7 can change from a transmission surface that transmits light to a diffusion surface that diffuses light according to an applied voltage. On the focusing screen 6, the liquid crystal 7 displays a frame 30 showing the autofocus range and a data display section 32 showing the measurement distance. The focusing screen 6 is provided with ten first transparent electrodes 13a for supplying a voltage to be applied to each liquid crystal 7 for display and three second transparent electrodes 13b for discriminating the type of screen. ing. The second transparent electrode 13b is provided to determine the type of the focusing screen depending on whether or not the other two are electrically connected to one transparent electrode. That is, two bits are formed by the three second transparent electrodes 13b,
It is possible to distinguish four types of screens. Since the type of focusing screen is determined by the second transparent electrode 13b, the type of applied voltage and the number and position of the first transparent electrodes 13a to which the voltage is applied are determined at the same time. As a result, a voltage is applied from the predetermined first transparent electrode 13a to the liquid crystal 7 and the liquid crystal 7 becomes cloudy, and the frame 30 or the data display 32 is displayed.

FIG. 5 shows another type of focusing screen 6. The focusing screen 6 is mainly used for manual focusing. This focusing screen 6 has four first transparent electrodes 13a and three second transparent electrodes 13b, and is provided with a central portion 34 and a peripheral portion 36 of the screen on which the liquid crystal 7 can be changed separately. As with the focusing screen 6 shown in FIG. 4, the type of the focusing screen 6 is determined by the connection state of the second transparent electrode 13b, and a predetermined voltage is applied to the predetermined first transparent electrode 13a. When a single-lens reflex camera in which the focusing screen 6 shown in FIG. 5 is used is equipped with a wide-angle lens, the amount of light around the screen decreases, so the peripheral area of the screen becomes dark when shooting a dark subject. In order to make it difficult for the photographer to see, the voltage applied to the peripheral portion 36 is reduced to reduce the white turbidity. Further, when a telephoto lens is attached to this single-lens reflex camera, since the depth of field is shallow and accurate focusing is required, the central portion 34 and the peripheral portion 36 both have high turbidity to form a full mat. Since various focusing screens provided with the connection terminals to be electrically connected in this way can be used by being exchanged according to various shooting conditions, it is possible to shoot as intended by the photographer.

Next, a circuit configuration including the focusing screen 6 will be described with reference to FIG. Focusing screen 6
The first transparent electrode 13a is connected to the LCD driver 40 for driving the liquid crystal 7, and the second transparent electrode 13b is connected to the discrimination circuit 42 for discriminating the type of the focusing screen 6. The LCD driver 40 and the discrimination circuit 42 are connected to a CPU 44 to which various information is input. The CPU 44 has an AF (autofocus) sensor 46 for autofocus, an AE sensor 48 for automatic exposure, a lens information sensor 50 for detecting a lens state, and a mode such as a shooting mode. The mode information sensor 52 is connected. Therefore, various kinds of information are input to the CPU 44, whereby the CPU 44 provides the LCD driver 40 with information according to the type of the focusing screen, and according to the information, the driving voltage is supplied from the LCD driver 40 to the focusing screen 6. It As a result, predetermined information corresponding to the type of focusing screen is displayed on the focusing screen.

Although the three transparent electrodes for discriminating the type of the focusing screen are provided in the above-described embodiment, the number of the transparent electrodes is not limited to this, and any number of transparent electrodes may be provided depending on the discriminating type.
In addition, the number of conductive parts and terminals provided for driving the liquid crystal of the focusing screen can be set variously to correspond to various focusing screens.

[Advantages of the Invention] There is provided a single-lens reflex camera in which a focusing screen having an electrical connection can be replaced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the configuration of an embodiment according to the present invention, FIG. 2 is a side view showing a focusing screen mounted, and FIG. 3 is a focusing screen mounted. Sectional view showing an optical system of the single-lens reflex camera in a state, FIG. 4 is a plan view showing an embodiment of a focusing screen, FIG. 5 is a plan view showing another embodiment of the focusing screen, and FIG. FIG. 3 is a circuit diagram schematically showing a circuit having a focusing screen according to the present invention. 6 ... Focusing screen, 12 ... Electrode mounting part, 13a ... First transparent electrode, 13b ... Second transparent electrode, 14 ...
... conductive rubber, 15a ... first conductive part, 15b ... second conductive part,
16 …… Terminal plate, 17a …… First terminal, 17b …… Second terminal, 18
…… Screen holding frame, 19 …… Bottom, 20 …… Protrusions, 22…
… Hinge part.

Claims (3)

[Scope of utility model registration request] 1. A focusing screen detachably attached to a camera body, liquid crystal display means provided on the focusing screen for changing display by being excited by an electric signal, and on one surface of the focusing screen. ,
A plurality of contacts arranged side by side so as to be exposed along at least one side outside the field of view of the focusing screen and electrically connected to the liquid crystal display means; A conductive rubber that is provided between a connection terminal for supplying a drive voltage to the display means, the camera body and the focusing screen, and electrically connects the plurality of contacts to the connection terminal. A single lens reflex camera comprising: 2. A focusing screen detachably attached to a camera body, and on one surface of the focusing screen,
By contacting at least one electric contact provided so as to be exposed along at least one side outside the field of view of the focusing screen and the electric contact provided on the camera body and on the focusing screen, A single-lens reflex camera, comprising: an identification unit for identifying the type of the focusing screen. 3. A focusing screen detachably attached to a camera body, wherein liquid crystal display means provided on the focusing screen for changing display by being excited by an electric signal is provided on one surface of the focusing screen. ,
A conductive rubber which is arranged side by side so as to be exposed along at least one side outside the visual field range of the focusing screen, is electrically connected to the liquid crystal display means, and is provided between the camera body and the conductive rubber; A focusing screen for a single-lens reflex camera, comprising: a plurality of contacts to which a driving voltage for the liquid crystal display means is supplied from the camera body when brought into contact with each other.