Abstract: Positioning of a magnetic head for recording a signal on a magnetic recording medium is performed in accordance with an absolute track address system. However, due to mechanical errors, expansion or contraction of the magnetic recording medium caused by changes in temperature or humidity, or small variations between recording apparatuses, a deviation can occur between a position recorded on in the past and a absolute track position thereof. Accordingly, with regard to at least one track that has already been recorded on, the amount of deviation between the peak position of the envelope of a signal on this track and an absolute track position is measured. Then, based upon the measured amount of deviation, the position at which the magnetic head is stopped on the track to be recorded on next is corrected.

Abstract: A white balance correction apparatus for electronic cameras is provided with a first photosensor which photometries a first light from the environment including a scene to be taken and a second photo sensor which photometries a second light from the scene. First and second identification circuits electrically identify the light sources of the first and second lights respectively based on electrical signals from the first and second photosensors. From the result of the identification of the light sources, an operation mode of a white balance correction circuit is selected from among three operation modes: one of a normal mode is which white balance correction is carried out according to a color temperature of the first light, a fluorescent lamp mode in which white balance correction is carried out to avoid a tinged image due to a fluorescent lamp, and a manual mode in which white balance correction is carried out according to a color temperature which is manually set is selected.

Abstract: A camera changeable between an ordinary photographic mode and a flash photographic mode includes a light source identifying device for identifying the illumination light provided from a fluorescent lamp based on an output from a light measuring device. The light source identifying device is detects ripple components of the output from the light measuring device to provide a flash control signal if the detected ripple components are higher than a predetermined level. The camera is changed into a flash photographic mode in response to the presence of the flash control signal in spite of the brightness of the subject field.

Abstract: A camera having an ordinary automatic exposure function which automatically decides a proper shutter speed and f-stop based on the results of photometry is additionally provided with a slow-photography mode. When the camera is set to the slow-photography mode, a predetermined shutter speed and f-stop outside a range of shutter speeds and f-stops capable of being set by ordinary automatic exposure control is set. This makes it possible to photograph night scenes, fireworks displays and the like. Photography is possible even in a light-value region in which the camera shutter would be locked against release in ordinary automatic exposure control owing to too little light.

Abstract: In an electronic still-video camera capable of frame recording using a shutter, read-out is controlled in such a manner that dark currents generated in an imaging device will be equal in both first and second fields. Thereby, the recording of a still-video signal that will provide an excellent and easy-to-view reproduced image that is free of flicker is made possible.

Abstract: A magnetic recording/reproducing device which has a track search function to discriminate a recorded track from an unrecorded track for all tracks formed in a magnetic disc. In the magnetic recording/reproducing device, in accordance with signals output from a magnetic head when the magnetic head is moved to positions lying at least adjacent to the central position of a track accessed, with a predetermined position on the magnetic disc designated as a reference position, it is determined whether each accessed track is a recorded track or an unrecorded track. Data representing the check results are stored in memory corresponding to the track numbers respectively given to the tracks. This assures an accurate track search.

Abstract: An apparatus for positioning a recording or playback head over a rotating recording medium, such as a magnetic disk. When access to a desired track is attempted, the head is quickly moved and placed within a range close to the track under open loop control. When the head enters the range close to the desired track, the head control is switched to servo feed under closed loop control. During the servo feed, the head is moved according to a head position signal representing the actual position of the head, the head position signal being given by a head position detector having a portion moving together with the head. The head is thus directed to a predetermined position according to an error signal corresponding to the deviation of the head position. When the head has passed through the desired position, driving force in the reverse direction is generated and the head is forced back toward the desired position. The head thus oscillates around the desired position but converges to it.

Abstract: For the purpose of detection of a zero-cross point of an input signal, the input is applied to one of two input terminals of a comparator which has an inverted input terminal and a non-inverted input terminal, the same bias voltage is applied to each of two input terminals of the comparator from a bias voltage supplying circuit, the value of the bias voltage applied to either the inverted input terminal or the non-inverted input terminal of the comparator is changed by a bias voltage changing circuit from that determined by the bias voltage supplying circuit depending on whether the output of the comparator is in its high or low level, the output of the comparator is a detection signal of the zero-cross point of the input signal.

Abstract: A camera control device connected with an electronic still camera, a master camera and a strobo device, in which the shutter release operation of both camera is controlled so that, when a release switch of the camera control device is turned on, shutters of the electronic still camera and the master camera open, and the strobo device is caused to emit light while both shutters are opened.

Abstract: A light source discriminating apparatus includes three photosensors, two of which have similar spectral sensitivity characteristics to each other. The apparatus senses the difference in the energy distribution of light sources by comparing the ratios of the light intensity sensed by these photosensors. In this manner, the type of a light source having a spectrum peak in the energy distribution of the light emanating from the source may be discriminated as a fluorescent light source, for example. The results of discrimination may be used effectively for adjusting white balance or shutter speed of a video or electronic still camera.

Abstract: A data signal is modulated by an exclusive-OR operation applied to a carrier signal and a data signal to be recorded. Demodulation is similarly performed by an exclusive-OR operation applied to the carrier signal and signal indicative of read data. This makes it possible to construct the modulating/demodulating circuit in the form of a digital circuit.

Abstract: A white balance adjusting device for use in a camera which photographs a field and forms a video signal representing the field. In the white balance adjusting device, while a sequential photographing is under way, updating of the color temperature data to be used for adjusting a white balance is prohibited. Therefore, the hues of main objects in the respective frames of still images photographed by the sequential photographic operation remain unchanged, thereby maintaining the homogeneity of the main objects. Also, in the white balance adjusting device, control a device is used to provide a short response time for a quick response property in a still mode and to provide a longer response time in a movie mode when compared with the still mode. As a result, the white balance can be adjusted according to the photographic modes of the camera.

Abstract: A video camera is arranged adjacent to a master camera with a silver halide film so as to pick up an image of the same subject as that to be taken by the maser camera. The video signals of a plurality of fields supplied from the video camera are stored in a memory. The video signals of fields of a predetermined number corresponding to the memory capacity are stored in such manner that a new input video signal is stored with erasing the oldest video signal stored therein. The video signal delayed by a predetermined fields from the oldest video signal stored in the memory is read out to supply the read out signal to a video monitor device.

Abstract: A rotary magnetic disc device suitable for use in a magnetic recording/reproducing apparatus in an electronic still camera or the like. In the rotary magnetic disc device, a cover lock mechanism, a regulation plate drive mechanism and a center core push drive mechanism can be operated by use of a movable plate the movement of which can be controlled by a cam and, therefore, an operation to remove the locking of a cover, an operation to retreat a regulation plate and an operation to remove the pushing against a center core can be performed by a single drive source, so that a compact rotary magnetic disc device can be obtained.

Abstract: A device for tracking a rotary recording medium includes a playback head for reading a signal from any of a plurality of tracks which are formed on the rotary recording medium, which is rotating at a predetermined constant speed, such that a beginning and an end of a recording in each of the tracks coincide with each other, a head support mechanism supporting the head such that the head is movable along the recording medium, an arrangement for detecting an envelope of a signal which is read out of the recording medium by the head, and a controller for controlling the head support mechanism to move the head to a position where a desired one of the tracks is located. An arrangement for detecting a position of the head relative to the recording medium and an arrangement for detecting a rotation phase of the recording medium are provided.

Abstract: A still video camera includes a color temperature sensor for detecting the color temperature of ambient light which is used in the color balance adjustment of video signals outputted from an image pickup system. The camera further includes a strobe emission circuit which produces a signal indicating when strobe emission is capable of being performed. A control circuit controls the adjustment of the color balance of the video signals on the basis of the color temperature detected by the color sensor in the absence of a strobe ready signal. Upon the activation of a shutter release switch, the control unit determines whether or not a strobe ready signal is present. If a strobe ready signal is present, the control unit fixes the color temperature to a predetermined constant value for color balance adjustment.

Abstract: When a disc pack containing a magnetic disc is loaded in a still video camera, all tracks on the magnetic disc are searched to determine whether each track has been recorded on or is blank, and the results of the search are stored in memory. If a continuous picture-taking mode has been set, the magnetic head is fed forwardly from a home position and is positioned on a track next to the last track recorded on. Since all of the remaining tracks from the track at which the head has been positioned to the final track of the disc will be blank, feeding of the magnetic head during the continuous picture-taking operation is simplified. In other words, in the continuous picture-taking mode, it will suffice merely to feed the head one track at a time each time a still picture is taken.

Abstract: An apparatus for positioning a recording or playback head over a rotating recording medium, such as a magnetic disk. When access to a desired track is attempted, the head is quickly moved and placed within a range close to the track under open loop control. When the head enters the range close to the desired track, the head control is switched to servo feed under closed loop control. During the servo feed, the head is moved according to a head position signal representing the actual position of the head, the head position signal being given by a head position detector having a portion moving together with the head. The head is thus directed to a predetermined position according to an error signal corresponding to the deviation of the head position. When the head has passed through the desired position, driving force in the reverse direction is generated and the head is forced back toward the desired position. The head thus oscillates around the desired position but converges to it.

Abstract: A data signal is modulated by an exclusive-OR operation applied to a carrier signal and a data signal to be recorded. Demodulation is similarly performed by an exclusive-OR operation applied to the carrier signal and signal indicative of read data. This makes it possible to construct the modulating/demodulating circuit in the form of a digital circuit.

Abstract: A motor control apparatus includes a driving unit having a motor for rotating a body at a predetermined rotating speed; a reference position detecting unit for determining a reference position in a rotation of the body and for generating a phase signal representing the reference position; a phase controller for controlling the driving unit by use of the bias signal as a reference so that a generation of the phase signal causes the rotation of the body to be brought within a predetermined range with respect to a reference signal; and a bias control unit interconnected to the phase controller for determining a difference in phase of the phase signal from the reference signal to provide the phase controller with the bias signal according to the determined difference.