Abstract: An automatic exposure camera in which any one of four modes, specifically, an aperture-priority automatic exposure mode, a shutter-speed-priority automatic exposure mode, a programmed automatic exposure mode and a manual exposure mode, can be readily set with reduced danger of improper selection. An automatic/manual switch is operated in association with a lens aperture ring to select one of an automatic aperture mode and a manual aperture mode for a lens of the camera. A mode A counter responds to the output of the automatic/manual switch to be made active when the automatic aperture mode is selected, and a mode M counter responds to the automatic/manual switch to be made active when the manual mode is selected. The output of one of the mode A counter and the mode M counter is selected for counting signals from the up or down switch to thereby set the exposure mode according to a count value so obtained.

Abstract: An automatic focus detecting camera in which the full-aperture f-number of a lens mounted on the camera is automatically detected and applied to a focus detecting circuit. The lens is provided with indicating pins in a pattern indicative of a full-aperture f-number of the lens. Switch contact pins are provided on the lens mount of the camera positioned corresponding to the positions of the indicating pins, with the switch contact pins being operated in accordance with the presence or absence of the corresponding indicating pins. The states of the switch contact pins are decoded to provide data indicative of the full-aperture f-number of the lens. If the lens does not have any indicating pins, the decoding circuitry outputs a fixe value, which can be shifted by a manual switch on the body of the camera. Also, a manual switch may be provided on the body of the camera for instructing the full-aperture f-number in the case that the lens does not have any indicating pins.

Abstract: A manual aperture value setting circuit for a camera in which digital values corresponding to the full-aperture value and the minimum aperture value of a lens mounted on a camera are applied from the lens in digital form to a logic circuit which operates so that, with the range of aperture value set on the side of the camera being maintained in the aperture value range of the lens, the aperture value which has been set is changed to the full-aperture value or the minimum aperture value of the lens when it is out of the aperture value range of the lens.

Abstract: A photographing mode selecting circuit for a camera having a very low power consumption. A mechanical switch is provided for each possible photographing mode of the camera. Each mechanical switch is coupled in series with a resistor and an analog switch between the power source terminals. The analog switches are periodically pulsed to close them, thereby allowing current to flow through the corresponding resistor and mechanical switch if the mechanical switch is closed. The outputs formed at the junctions between the analog switches and the resistors are applied to flip-flop circuits for storage.

Abstract: A device for controlling a light source in a viewfinder of a camera, such as may be used for illuminating a liquid crystal display unit, having a simple operation and which is saving of power. An operating switch is provided for operating the light source. A timer is initiated when the operating switch is turned off. The light source is maintained turned on while the operating switch is turned on and while the timer is operating, and the light source is turned off when the operating switch is turned on during the operation of the timer.

Abstract: In an automatic diaphragm stop down operation square wave pulses are generated, the number of which represents the extent of diaphragm stop down. Short pulses are generated responsive to the leading and trailing edges of the square wave pulses. The short pulses are counted. After a predetermined number of short pulses are counted, diaphragm stop down is arrested. In one embodiment, when a periodic input signal representative of the extent of diaphragm stop down rises above a first threshold, the square wave pulses are produced at a first level and when the input signal drops below a second threshold lower than the threshold, the square wave pulses are produced at a second level.

Abstract: A photographic camera of interchangeable lens type has an interchangeable objective that can be removably mounted on a camera body and a plurality of switches each capable of assuming a first or a second state. The switches all assume the same state when the objective is removed from the camera body and selectively assume the first and second states according to the value of at least one lens characteristic when the objective is mounted on the camera body. An automatic exposure control mechanism is operated responsive to the selectively assumed states of the switches when the objective is mounted on the camera body. A shutter release mechanism is disabled responsive to said same state of all the switches.

Abstract: A shutter speed display device for a camera in which light emitting diodes are arranged in a viewfinder of the camera with one light emitting diode corresponding to each of a plurality of shutter speed indicating numerals. The light emitting diodes are connected in a matrix format and driven in a time division manner so that one or more of the light emitting diodes can be simultaneously activated so as to display both the selected shutter speed and to indicate whether the picture would be under-exposed or over-exposed. In one embodiment, both the shutter indicating light emitting diode and the under-exposure and over-exposure diodes are switched on and off at a high rate of speed so that their light output appears to be stable to the operator. In a second embodiment, the light emitting diodes for indicating the under-exposure and over-exposure conditions are made to flicker.

Abstract: An electric source circuit for a camera in which the voltage of a power source is automatically applied to the exposure control and display circuit of a camera when the electronic flash is fully charged. A first switch circuit is operatively coupled between a power source and the exposure control and display circuit. A photometric switch for controlling the conduction and non-conduction of the first switching circuit is coupled in parallel with the second switching circuit. The second switching circuit is coupled to detect when the electronic flash mounted on the camera is fully charged. A third switching circuit can be provided for activating an indicating device such as an LED or piezoelectric transducer.

Abstract: A circuit for controlling an exposure time of a camera which operates depending on whether or not an electronic flash used with the camera is charged and ready for operation. An arithmetic operation circuit operates upon signals representing object brightness, film sensitivity, and aperture value and exposure factor compression values to calculate an automatic exposure time. The output of the arithmetic operation circuit is multiplexed with the output of a manual exposure time setting circuit to an expansion time determination circuit. The manual exposure time setting device output is multiplexed through a first gating means with the output of a counter which operates in response to an oscillator. Multiplexed outputs are coupled to an input port of a digital-to-analog converter the output of which is coupled to one input of an analog-to-digital converter and the other input of which is coupled to the output of the arithmetic operation circuit.

Abstract: A combined manual and automatic exposure time control circuit for a camera in which automatic exposure data produced through photometric techniques and manual exposure data set manually are coupled through a switching circuit to a time determination circuit which controls the camera exposure time. The automatic exposure data is produced by a calculation circuit which receives inputs relating to the logarithmic compression values of the object brightness, the film sensitivity, aperture value and exposure setting to thereby digitally calculate the proper exposure time. The output of the calculator is selectively coupled through a switching circuit along with the analog-to-digitally converted manual exposure time setting data to an expansion time determination circuit.

Abstract: A digital exposure display circuit operates a display element to display exposure information in a camera employing selectable photographing systems including a lens stop priority system, a shutter speed priority system and a manual photographing system. The display circuit includes a first circuit for outputting a voltage proportional to the sum of the brightness of an object to be photographed and a film sensitivity and a second circuit for outputting a voltage proportional to a value obtained by substracting a lens stop value from the output of the first circuit. The display circuit also includes a constant voltage source and a voltage source for providing a voltage corresponding to a manually set shutter speed. A single analog-to-digital converter is provided to generate part of the address of a read only memory.

Abstract: Full and minimum aperture information is transmitted to a camera body from an interchangeable lens by coding possible combinations of the two values into various discrete single values and transmitting the single value to a decoder in the camera body. For instance, a projection may be provided on the lens barrel having a height corresponding to a particular combination of full and minimum aperture values.

Abstract: A display device in the view finder of a camera with display capability in which a read only memory is addressed by photographing data of the camera which have been converted into digital data. A display element is driven by output data from the read only memory to visually display the data such as shutter speed, f-stop, etc. The instruction which will completely turn off the display element is stored in said read only memory, and turning off the display element is controlled by addressing said read only memory.

Abstract: A display device in the view finder of a camera in which relevant photographing information is displayed digitally by display elements. A logical product of an electrical signal is generated by a switch operated when said camera is set for self-timer photographing or, when the camera is set for bulb photographing. This signal and an electrical signal provided upon start of photographing, are employed and the lighting of the display elements in the finder is stopped in synchronization with the start of self-timer photographing or with the start of bulb photographing.

Abstract: An indication device in a single lens camera of through-the-lens automatic exposure control type. The device comprises an aperture control device for controlling an aperture value by utilizing an object brightness (B), a film sensitivity (S) and a manual shutter speed (T). Also, a shutter control device is employed in which stopped-down metering is carried out by using an aperture value (A) controlled by the aperture control device. An actual aperture value controlled by the aperture value (A) and a shutter speed are automatically set according to the object brightness and film sensitivity to have a suitable exposure value according to the following equation:A.sub.V =S.sub.V +B.sub.V -T.sub.Vwhere: A.sub.V is the APEX indication value of the aperture value, S.sub.V is the film sensitivity, B.sub.V is the object brightness, and T.sub.V is the manual shutter speed. When the aperture value controlled is at the full-aperture value (A.sub.

Abstract: A digital display device is disclosed which is used for digitally displaying correct exposure time. The display device includes a repetitive pulse generator for generating repetitive pulses to control the charging-discharging operation of an integration capacitor. The number of clock pulses produced by a clock pulse oscillator during the period in which the charged voltage level on the capacitor is increased to the output level of a light measuring circuit which is proportional to the logarithmic value of the brightness of an object to be photographed starting from the voltage level of a reference voltage source is counted by a counter. An LED display is energized by the counter output through a decoder.

Abstract: A digital exposure meter display circuit for a camera includes a first oscillator 1 whose output controls the charging of an integrating capacitor 28 from a constant current source 3. When the capacitor charge reaches the level of a reference voltage from source 7, as detected by a first comparator 6, a counter 10 is enabled and begins to register clock pulses from a second oscillator 8 through an AND gate 31. When the capacitor charge subsequently reaches the output level of a light measuring circuit 4, which is proportional to the apex value of the sensed object brightness, a second comparator 5 disables the AND gate and enables an LED display 12 supplied with the decoded counter value.

Abstract: In a camera, a numerical indication of the shutter speed is displayed thru the viewfinder. Numerals corresponding to the several shutter speeds are arranged to be illuminated, and therefore visible, by light emitting diodes associated therewith. The array of light emitting diodes have their cathode and anode terminals coupled together in groups arranged to reduce the total number of external connections to the diode array. The shutter speed is converted to a digital value which is applied to a decoder. The decoder energizes the external terminals of the diode array to selectively energize only one diode, corresponding to the shutter speed.

Abstract: A circuit for disabling the LED display L1-L5 in the light meter of a single lens reflex camera in response to mirror movements. When the mirror 21 is raised the switch 17 is closed which reverse biases the LEDs. After the mirror is lowered the switch 17 is opened to enable the LEDs, but a short time delay is provided to allow transients to settle out by reason of a capacitor 18 which must first charge through a grounding resistor 19.