Asahi Kogaku Kogyo Kabushiki Kaisha

Yoshio Sawada

Masahiro Kawasaki

Harumi Aoki

Eiichi Tano

Katsuhiko Miyata

Yukio Takaoka

Fumio Urano

Seijiro Tokutomi

An automatic focus indicating device especially adapted for use with a single lens reflex camera in which a contrast signal is produced by scanning the image of an object being viewed through the photographing lens of the camera. This signal is converted into an indication signal which may be either an audio or a visual signal. As the lens is moved to positions near the focus point, the indicating device is activated to a first mode. As the lens is set precisely upon the point of focus, the indicating device operates in a second mode. In this manner, the camera is well adapted for both hand-held and fixed position usage.

Automatic focus indicating device for camera

A focus detecting device for a camera utilizing a self-scanning type photoelectric element array composed of a plurality of minute photoelectric elements. The input signal from the photoelectric element array is held by first and second memory circuits at opposite phases from one another with the holding time for the memory circuit corresponding to twice the scanning time for a single minute photoelectric element within the array. Signals representing the difference and sum of the output of the memory circuits are formed and the absolute value of the difference signal is taken. The sum signal is connected as the divisor signal to a divider circuit while the absolute value of the difference is utilized as the dividend. The peak value of the signal thus formed is utilized as a contrast detection signal. This signal is substantially unaffected by vibration of the camera or movement of the object being photographed.

Focus detecting device

An automatic focus detecting device for a camera in which a contrast signal is produced which is made independent of variations and brightness of the object being viewed and of vibrations of the camera by utilizing an out-of-focus image on an average illumination detecting photoelectric element. The average illumination detecting photoelectric element is disposed in a plane perpendicular to the optical axis of an optical image of the camera. A pulse generator produces an output clock pulse signal having a frequency which is controlled by the output signal from the average illumination detecting photoelectric element. A self-scanning type photoelectric element array is scanned with this variable frequency clock pulse train wherein the frequency of the clock pulses is increased when the brightness of the object being viewed increases to thereby increase the dynamic range of the device.

Camera focus detecting device

An automatic focus detecting and indicating device for an camera in which a contrast signal is coupled through first and second analog switches directly to a difference circuit and through a peak hold circuit, respectively. A third analog switch is coupled so as to discharge the value stored in the peak hold circuit. The three switches are operated by a control circuit which in turn operates in accordance with the direction of movement of the lens and the detection of a rising edge of the contrast signal so as to prevent the generation of a false focus signal at other than the point of true focus.

A focusing system for a camera using an array of photoelectric elements to sense the level of light at points in the image plane of an objective lens. The output of the elements are scanned in sequence to form a train of pulses whose amplitudes correspond to the level of light at the respective elements as they are scanned. The pulse train is split into two pulse trains of alternate pulses. The two pulse trains are separately converted to two analog signals and applied to a differential amplifier. The difference output is clamped to a reference potential and applied to a peak detector. When the objective is in focus, the output of the peak detector is at a maximum.

Focus detecting device for photographic camera

An automatic focus detecting device for a camera in which a self-scanning photoelectric element array is scanned at a rate depending upon the average amount of light reflected from an object being photographed so that accurate focus detection is maintained over a wide range of illumination conditions. An average illumination detecting element is disposed at a position near or at a position optically equivalent to that of the microphotoelectric elements of the element array. A low-pass filter couples the output of the average illumination detecting element to a clock pulse generator which produces clock pulse signals of which the frequency varies according to the smoothed output signal from the low-pass filter representing the average illumination. As the brightness of the object increases the frequency of the clock pulse signal correspondingly increases to compensate for variations in brightness of the object.

An automatic focus detecting device for a camera including a self-scanning type photoelectric element unit including plural minute photoelectric elements disposed in a plane corresponding to the position of the image forming plane of the photographing lens of the camera. The photoelectric element unit is scanned and the output signals from the unit are sampled and held over a scanning time period. The output signals from second adjacent ones of the elements are coupled to differential circuits the outputs of which are multiplexed onto a single output line. The peak value of the multiplexed signal is detected. When the peak value signal is at its maximum, the camera will be in proper focus.

A power supply maintaining circuit in a camera having an electric source, and a power switch provided between the electric source and a shutter control circuit or a display circuit. The power supply maintaining circuit comprises a timer circuit connected in parallel to the shutter control or display circuit and a transistor is connected in parallel to the power switch. The transistor is controlled by the timer circuit.

Camera power supply maintaining circuit

A signal indicating that the correct exposure value has been achieved and a signal indicating the completion of flash are logically summed to provide a shutter closing signal. This ensures that the shutter will be closed even when the light emitted by the flash is insufficient to achieve the proper level of exposure.

Long time exposure preventing device for camera with electronic flash

A novel photometric circuit for a camera is disclosed wherein the operational amplifiers common to conventional photometric circuits are eliminated from that part of the circuit which solves the exposure Apex indication equation: S.sub.v +B.sub.v =A.sub.v +T.sub.v. The variable resistors which are used to convert the film sensitivity and aperature settings into electrical quantities are positioned in the feedback circuit of the transistor which is connected to the electro-optical transducer and which develops a voltage dependent upon scene brightness.

Photometric circuit

An electrically controlled camera device is disclosed which includes a counter for counting the number of pulses representative of the preferentially selected one exposure condition of a shutter speed and a diaphragm aperture level to control the preferentially selected one exposure condition, and a digital operation circuit for calculating the other exposure condition in the form of a number of digital pulses in accordance with the output pulses from the counter and with digital data signals representative of the sensed scene brightness and the film sensitivity used. During automatic exposure, the number of pulses counted by the counter is controlled by the combination of a pulse generator and a single-throw mechanical switch connected between the pulse generator and the counter, and the number of output digital pulses from the digital operation circuit is counted by another counter for controlling the other exposure condition. During manual exposure, the number of pulses representative of the other exposure condition is controlled by the combination of the pulse generator and another single-throw mechanical switch and counted by the other counter coupled to the pulse generator through an automatic/manual change-over switch and the other single-throw mechanical switch and controlling the other exposure condition. Both the single-throw mechanical switches are arranged to be operated by corresponding push buttons mounted outside the camera housing, and two sets of indicator lamps for displaying both the exposure conditions are arranged within the field of view of the camera finder.

Electrically controlled camera device

An exposure control operation involving diaphragm adjustment is performed in first and second phases. During the first phase, a drag mechanism controls the rate of change of diaphragm value. During the second phase, a braking mechanism cooperates with the drag mechanism to control the rate of change of diaphragm value.

Diaphragm-type exposure control system having braking arrangement

An auxiliary brake control device for use in an automatic exposure camera of the lens stop value control type permits the lens stop operation to be controlled with high accuracy without substantially increasing the lens stop operation time. The auxiliary brake control device is controlled by comparing the variation rate in the measured light which passes through the lens stop with a preset value. In this way, lenses which have different characteristic variation rates can be freely interchanged.

Lens stop auxiliary brake control device in automatic exposure camera of

An analog-to-digital converter circuit for a photographic exposure meter includes a plurality of parallel connected transistors 51, 54, 57 and 60 whose bases are connected to the logarithmic output of a light measuring circuit A. The transistor collectors are driven by constant current sources comprising an equal plurality of transistors 50, 53, 56 and 59 having emitter area ratios of 1:2:4:8, whereby the collector voltages of the transistors represent a digital threshold conversion of the light measuring circuit output.

Digital display circuit for a photographic exposure meter

A novel photometric circuit for a camera is disclosed wherein the operational amplifiers common to conventional photometric circuits are eliminated from that part of the circuit which solves the exposure Apex indication equation: S.sub.v + B.sub.v = A.sub.v + T.sub.v. The variable resistors which are used to convert the film sensitivity and aperature settings into electrical quantities are positioned in the feedback circuit of the transistor which is connected to the electro-optical transducer and which develops a voltage dependent upon scene brightness.

Growing community of inventors

Tokyo, Japan

Yoshio Sawada