JPS6045233A - Release malfunction preventing device - Google Patents

Abstract

PURPOSE:To prevent the malfunction of a release in an exposure controlling circuit, etc. by supplying automatically an operable signal only when a lens is installed completely in accordance with attachment and detachment of lens. CONSTITUTION:When a lens is not installed completely to a body mounting surface 4, terminals 2, 5, and 3, 6 do not abut on each other; then a lens installing signal to an OR gate circuit 7 goes to H level, but L level when said lens is installed completely. When a release switch S9 is in an opened state, the release button signal of an input terminal 10 goes to H level. When the S9 is closed by operating a release button, the release button signal goes to L level. Accordingly, a release signal inputted to an exposure controlling circuit 14 from an output terminal 13 of the circuit 7 goes to L level for the first time in a state that a lens installing signal inputted to the input terminal 8 of the circuit 7 and the release button signal inputted to the input terminal 10 have attained to L level simultaneously, then the circuit 14 is operated.

Description

[Detailed description of the invention] The present invention is a single-lens reflex camera, an electronic reflex camera.

The present invention relates to a release malfunction prevention device for cameras with interchangeable lenses, such as video cameras.

In cameras with interchangeable lenses, in order to prevent the exposure control circuit from being activated by accidentally pressing the release button, it is conventional practice to turn off the power to the release device with a switch, or to mechanically lock the release button. Measures were taken to protect the area.

However, operations such as turning off the power to the release device and mechanically fixing the release button when attaching and detaching the lens are cumbersome and become an obstacle when quick lens replacement is required, so the malfunction prevention means described above There are many inconveniences such as not operating or forgetting to operate the shutter release button, and inconveniences such as pressing the release button by mistake and activating the exposure control circuit, and furthermore, if the lens is not fully attached, the aperture cannot be controlled accurately. Normal exposure is not achieved because the resistance value corresponding to the aperture aperture is not accurately transmitted from the lens side to the rebody side, but conventional photographic devices have means for detecting the incomplete attachment of the lens. Because the photographer was not aware of this, there were times when he or she would expose the subject without realizing it.

The present invention has been made in view of the above points, and the exposure control circuit is prevented from operating when the lens is detached or incompletely attached, and is activated only when the lens is completely attached. It is an object of the present invention to provide a device that prevents a release from malfunctioning by automatically giving a signal enabling the exposure control circuit to an exposure control circuit as a lens is attached or detached.

Hereinafter, the apparatus of the present invention will be explained based on the drawings.

FIG. 1 shows an embodiment of the apparatus of the present invention. In FIG. 1, the lens indicated by the symbol l is provided with two terminals 2 and 3, which are short-circuited to each other. On the other hand, terminals 5 and 6 are also connected to the lens side terminals 2 and 3 on the body side mounting surface 4 when the lens 1 is completely attached.
Terminal 5 and terminal 6 are not short-circuited via mounting surface 4, and terminal 5 is connected to GND.
In addition, the terminals 6 are connected to input terminals 8 of an OR gate circuit 7, respectively. Further, a release switch 9, which is linked to the operation of a release button (not shown) and is closed by pushing the release button, is connected to an input terminal 10 of an OR gate circuit 7, GN, D.
It is located in the middle of the. The input terminal 8 and the input terminal IO of the OR gate circuit 7 are connected to Vcc through a resistor 11 and a resistor 12, respectively, which are set to II level, and the output terminal 13 of the OR gate circuit 7 is connected to the Game 1 - Well-known exposure control circuit 1 that operates when the output of the circuit is at L level
Connected to 4.

In the device of the present invention configured as described above, when the lens 1 is detached from the body-side mount surface 4 or in an incompletely attached state, the terminals 2 and 5 and the terminals 3 and 6 do not come into contact with each other. The lens mounting signal inputted to the input terminal 8 of the OR gate circuit 7 is at the I] level, and when the lens 1 is completely mounted, the lens mounting signal becomes the L level. On the other hand, when the release switch 9 is open, the release button signal input to the input terminal lO of the OR gate circuit 7 is high.
When the release switch 9 is closed in conjunction with the operation of a release button (not shown), the release button signal becomes L level. Therefore, the release signal inputted from the output terminal 13 of the OR gate circuit 7 to the exposure control circuit 14 is the same as the lens attachment signal inputted to the input terminal 8 of the OR gate circuit 7, and the release button inputted to the input terminal 10. It becomes L level only when the signals are both L level at the same time.
': Exposure control circuit 14 is activated.

FIG. 2 shows the sequence of an embodiment of the invention.

As mentioned above, when the lens is detached or incompletely attached, the lens signal is 1 level, and even if the release switch is closed at this time and the release button signal goes to L level, the release signal remains for Illll, so there is no exposure. Control circuit is not activated.

On the other hand, when the lens is fully attached, the 1 nons attachment signal is L.
At this time, when the release button signal goes to L level, the release signal which is the output of the OR gate circuit goes to L level and activates the exposure control circuit to perform exposure.

As described above, in the device of the present invention, when the lens is removed during lens exchange, etc., even if the "C" release button is pressed by mistake, the exposure control circuit does not operate, making it possible to prevent an involuntary release. Since there is no need to operate the release malfunction prevention device each time, it is possible to quickly change lenses.Furthermore, since the exposure control circuit does not operate even if the lens is not fully attached, it is possible to accidentally make an incorrect exposure without the photographer noticing. The effects are great, such as being able to prevent photographing.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an embodiment of the present invention, Fig. 2 (↓A Sequence of an embodiment of the invention. 1... Lens 2, 3... Lens side terminal 5.6.
・・Camera side terminal 7・・op) y'-1~INI j
! 33.10...Input terminal of OR gate circuit 9...Release switch 13...OR gate 1~Output terminal of circuit

Claims (1)

[Claims] Prevention of release malfunction in a camera with interchangeable lenses. The device inputs a lens attachment signal that determines whether the lens is completely attached to the camera body, and a release button signal that determines whether the release switch is closed, and outputs a release signal that starts exposure. 1. A release malfunction prevention device comprising a logic circuit.