JPS63121367A - Electronic still camera - Google Patents

Abstract

PURPOSE:To prolong the life of a battery by starting a disk motor after a current conducted to a constant-voltage regulated power supply reaches a constant state at the time of photographing, and operating a focus driving means and a shutter driving means in such a way that start current are not timely overlapped. CONSTITUTION:With the pressing operation in the first stage of a release button 9 distance information from an AF sensor 25 an object is inputted to a system control circuit 10. With the pressing operation in a second stage, a release signal (a) is inputted to the circuit 10. The circuit 10 turns on a DC/DC converter 22. If a voltage detection circuit 24 detects that an output from the converter 22 reaches the constant state, the disk motor 17 is started and a delay circuit 23 is operated. If the circuit 10 finds that a prescribed time has passed by the circuit 23, it starts a focus motor 6. An enco.der 8 detects the focus position and the motor 6 is stopped A shutter motor 5 is started after a surbo lock signal (q) is recognized. Thus, the titled camera is operated by a small and light battery, and the life of the battery can be prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electronic still camera that records instantaneous images of a subject on a magnetic disk.

Conventional technology Generally speaking, one of the major features of electronic still cameras that record and reproduce video signals on recording media such as magnetic disks is that, unlike photographic cameras that use silver halide film, recorded images can be instantly reproduced. If the recorded image fails or is unnecessary, the recorded image can be erased and recorded again as many times as desired.

FIG. 3 is a block diagram showing the configuration of a conventional electronic still camera. IQl, 102 is a lens for forming an image of the subject on the imaging surface of the imaging device placed on the 7-ocal plane;
103 is a lens shutter that also serves as an aperture for controlling the amount of exposure during exposure (hereinafter simply referred to as a shutter), 105 is a stepping motor that drives the shutter 103 (hereinafter referred to as a shutter motor), and 104 is a shutter motor drive circuit that drives the shutter motor 106. , 106 is a DC motor (hereinafter referred to as a focus motor) that moves the front lens portion 101 of the lens back and forth in order to focus the subject image on the imaging surface;
107 is a focus motor drive circuit that drives the focus motor 106; 108 is an encoder which is a well-known mechanical position sensor for detecting the position of the lens 101; and 109 is a control circuit for operating the AF sensor 125, which will be described later, and for photographing. A two-stage action release button that provides a trigger; 110 a system control circuit that controls the entire system; 111 an image sensor configured by mXn COD elements arranged two-dimensionally in a matrix; 112 a reference signal A video signal processing circuit 113 outputs, as a video signal to be recorded on a magnetic disk, accumulated charges corresponding to the brightness of picture elements corresponding to each division of the image sensor 111 that are taken out synchronously. 116 is a head drive circuit for moving the magnetic head 115 to form a plurality of recording tracks on the magnetic disk 114; 117 is a head drive circuit for recording on the magnetic disk 114;
118 is a disk motor control circuit for stably rotating the disk motor 117; 119 is a servo lock detection circuit for detecting that the rotation of the disk motor 117 has reached a stable state; 120; 121 is a rotation detector for detecting the rotational phase of the magnetic disk 114; 121 is a battery for supplying power to the entire system; and 122 is a regulator that receives power from the battery 121 and supplies stable voltage to each circuit system. A DC-DC converter 126, which is a voltage power supply, has an infrared light emitting part and a light receiving part, and is a well-known AF that measures the distance to the subject.
It is a sensor. Here, directly from the battery 121 D”;-DC
In addition to the converter 122, a disk motor 117° and a shutter motor 1o6. Power is also supplied to the focus motor 1o6° head drive circuit 116 and system control circuit 11Q. FIG. 4 is an operational waveform diagram of the electronic still camera configured as described above.

a' is a release signal generated by the second pressing operation of the release button 109, b' is an input current waveform from the battery 121 consumed by the DC-DC converter when the DC-DC converter 122 is turned on, and d' is the disk motor drive current waveform consumed when the disk motor 117 is turned on, θ' is the focus motor drive current waveform when the focus motor 106 is driven, and i' is the waveform of the focus motor drive current when the lens 101 is moved to the in-focus position by the encoder 108. The focus detection signal q', which is generated in the system control circuit 110 at a high level when the disc motor 117 is stabilized to steady rotation, is output from the servo lock detection circuit 119 which becomes a high level when the disk motor 117 is stabilized at a steady rotation. Servo lock signal, h' shutter 1 by shutter motor 105
A shutter drive period signal indicating a period in which 03 is operating;
i' is delayed as much as possible based on the rotation phase signal generated by the rotation detector 120 to become a timing signal for generating a recording gate such that the phase of the video signal recorded on the magnetic disk 114 becomes a predetermined value. j' is the recording gate signal for recording the video signal on the magnetic disk 114 approximately in synchronization with the PG signal i', and k' is the signal after recording. magnetic head 1
This is a head movement signal for moving the head 16 to the next recording track.

In the conventional electronic still camera configured as described above, by pressing the first step of the release button 109, the A
Distance information to the subject is input from the F sensor 125 to the system control circuit 110, and the information is stored. When the series signal a' is input to the system control circuit 110 by pressing the second stage of the release button 109, the system control circuit 110 supplies stabilized voltage to each circuit (DC-DC converter 122 , simultaneously activate the disk motor 117 through the disk motor control circuit 118 and the focus motor 106 through the focus motor drive circuit 107 to move the lens 101 to the focusing position based on the previous distance information.Lens 10
1 moves and the image of the subject at a certain distance is captured by the image sensor 111.
encoder 10B
When detected by , the system control circuit 11Q controls the focus motor 1oθ to apply a brake and then stops the focus motor 1oθ at that position. Next servo lock detection circuit 119
After confirming that the servo lock signal q' output from the shutter motor drive circuit 1 is at high level,
04 to drive the shutter motor 105 and open/close the shutter 103. The time during which the shutter motor 105 is driven, ie, the shutter drive period T3, changes depending on the brightness of the subject at the time of image capture, and is the time during which the imaging surface of the image sensor 111 is properly exposed.

When the exposure is completed, charges accumulated in each pixel of the image sensor 111 according to the luminance are taken out in time series in synchronization with a certain reference clock, and output as a video signal by the video signal processing circuit 112. This video signal is transmitted to the system control circuit 11
The data is recorded on the magnetic disk 114 by the recording circuit 113 via the magnetic head 116 in response to the recording gate signal j' synchronized with the PG signal i' formed by n. After this recording is completed, the system control circuit 110 sends a head transport signal h' to the head drive circuit 116 to move the magnetic head 115 to the next recording track. Thereafter, the DC-DC converter and each drive circuit are turned off, and the series of photographing sequences ends.

Problems to be Solved by the Invention However, in the above configuration, the release button 1
In order to shorten the time from the second pressing operation in Step 09 to exposure, the DC-DC converter 122, disk motor 117, and focus motor 106 are operated simultaneously after pressing the release button 109. For this reason, immediately after startup, a steady current and a fairly large transient current are combined, resulting in a large amount of current being consumed from the battery 121. In order to perform these operations normally, it is necessary to use a battery with a sufficiently large capacity, which becomes a major obstacle to miniaturizing the device. Furthermore, passing a large current intermittently, even instantaneously, shortens the life of the battery, and there is a practical problem in that the number of images taken per battery replacement or charging is small.

In view of the above, an object of the present invention is to provide an electronic still camera that can be driven with a small, low-capacity battery and that can capture a large number of images with a single battery replacement or charge.

Means for Solving the Problems The present invention forms a subject image using an optical system on the imaging surface of a solid-state imaging device that has both a photoelectric conversion function and a charge transfer function, and forms each pixel on the imaging surface. an imaging means for generating a corresponding video signal; a shutter and driving means for driving a lens shutter for controlling the exposure amount of the imaging surface; and an optical system for focusing the subject image on the imaging surface. a focusing drive means for driving; a focus detection means for detecting that the optical system is arranged to be in focus; a recording means for recording the video signal on a recording medium via a recording head; a disk motor for rotating a medium, a servo lock detection means for detecting that the disk motor has reached steady rotation, and a head moving means for moving the recording head so as to have a plurality of tracks on the recording medium; A constant voltage power supply that receives power from a battery and supplies a stable voltage to each circuit, a voltage detection means that detects whether this constant voltage power supply is outputting a predetermined voltage, and an output of this voltage detection means. a means for operating the disc motor by means of a motor; and a means for operating the focus drive means after a predetermined period of time has elapsed after starting the disc motor, and a shutter drive means for operating the focus drive means in accordance with the outputs of the servo lock detection means and the focus detection means. It is an electronic still camera that operates.

According to the above-described configuration, the present invention starts the disk motor after the current flowing through the constant voltage power supply during photography reaches a substantially steady state from a transient state, and after this starting current decreases to a predetermined value or less, the focus motor starts. is driven, and then an exposure operation is performed in which the shutter is driven.

Embodiment FIG. 1 is a block diagram showing the system configuration of an electronic still camera in an embodiment of the present invention. In Figure 1,
1.2 is a lens, 3 is a shutter, 4 is a shutter motor drive circuit, 5 is a shutter motor, 6 is a focus motor,
1 is a focus motor drive circuit, 8 is an encoder, 9 is a release button, 11 is an image sensor, 12 is a video signal processing circuit, 13 is a recording circuit, 14 is a magnetic disk, 16 is a magnetic head, 16 is a head drive circuit, 17 18 is a disk motor, 18 is a disk motor control circuit, 19 is a servo lock detection circuit, 20 is a rotation detector, 21 is a battery, 22 is D
These are a C-DC converter and an AF sensor 25, and their operations are the same as those of the conventional electronic still camera described above, so a description thereof will be omitted.

23 is a delay circuit that measures the time until the starting current, which flows several times the steady state after the disc motor 17 starts, reaches a predetermined value or less (substantially steady state); 24 is the DC-DC converter 2;
A voltage detection circuit 2 detects that the output reaches a predetermined voltage value, and a system control circuit 10 controls the entire system.

FIG. 2 is an operational waveform diagram of the electronic still camera of this embodiment.

The operation of the electronic still camera of this embodiment configured as described above will be described below.

By pressing the first stage of the release button 9, distance information to the subject is input from the AF sensor 26 to the system control circuit 10, and the information is stored. When the series release signal is input to the system control circuit 10 by pressing the second stage of the release button 9, the system control circuit 10
should supply a stabilized voltage to each circuit (turn on the DC-DC converter 22. At this time, the voltage detection circuit 24 monitors the output voltage of this DC-DC converter 22, and when it detects that it has reached a predetermined voltage, As shown in FIG. 2, a high level voltage detection output signal C is output to the system control circuit 10. This voltage detection output signal C being at a high level means that the current supplied from the battery 21 to the DC-DC converter 22 is As shown in FIG. 2 (b), it shows that the system has settled down from the rush (transient) state after startup to a steady state.

When the voltage detection output signal C becomes high level, the system control circuit 10 drives the disk motor 17 via the disk motor control circuit 18. At this time, the delay circuit 23 for measuring time is also operated. The delay circuit 23 indicates that the time T1 has elapsed until the current in the disk motor 17 becomes less than a certain predetermined value (this value depends on the capacity of the battery), as shown in the disk motor current waveform in FIG. 2d. Once the system control circuit 10 knows this, it then starts the focus motor 6 via the focus motor drive circuit 7 in order to move the lens 1 to the in-focus position based on the previous distance information. When the encoder 8 detects that the lens 1 has moved to the focused position, and the focus detection signal shown in FIG. (reverse current is applied) and then stopped at that position.

The drive current waveform of the focus motor 6 is shown in FIG. 2e.

Next, after confirming the high-level servo lock signal q indicating that the disk motor 17 is rotating stably, the shutter motor 5 is driven to open and close the shutter 3 to expose the imaging surface of the image sensor 11. . Thereafter, video signals are recorded on the magnetic disk 14 and the magnetic head 15 is moved as in the conventional example.

As described above, this embodiment focuses on the fact that a large current flows when the DC-DC converter, disk motor, and focus motor are started, but the current decreases significantly after that. Instead, the configuration is such that each starting current flows at different timings so that they do not overlap in time, so the battery capacity is not the sum of all starting currents, but the value when the starting current is the largest. It is only necessary to consider the battery capacity, which is extremely small compared to the capacity of the battery used in conventional electronic still cameras, and the current taken out from the battery can be averaged, making it possible to minimize the decrease in battery capacity. It is also possible to extend the life of the battery.

By the way, in the above embodiment, after the disc motor is started, a delay circuit is used to set the time during which the starting current becomes less than a certain predetermined value, but a current detection circuit is provided to detect the current value of the disc motor. The same is true when K is used to drive the focus motor after detecting that the value is below the value.

There is a concern that the time from when the release button is pressed until the start of photographing will be longer than in the past, but in reality, the increased time is about 100 mg, and there is no problem in practical use.

As described in detail, according to the present invention, the capacity can be made extremely small compared to the batteries used in conventional electronic still cameras, so a smaller battery can be used, and the battery life can be reduced. can also be extended. Therefore, it is possible to provide an electronic still camera that is small and lightweight and can take a large number of images with just one battery replacement or charging, and its practical effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an electronic still camera according to an embodiment of the present invention, FIG. 2 is an operation waveform diagram of the same embodiment, and FIG. 3 is a block diagram showing the configuration of a conventional electronic still camera. FIG. 4 is an operational waveform diagram of the conventional example. 1.2... Lens, 3... Lens shutter, 5... Shutter motor, e...
Focus motor, 13... Recording circuit, 14.
...Magnetic disk, 15...Magnetic head, 16...Head drive circuit, 1A...
Disc motor, 19...Servo lock detection circuit, 2o...PG, 21...Battery, 2
3... Delay circuit, 24... Voltage detection circuit. Name of agent: Patent attorney Toshio Nakao Nika 1 person 2nd person
Illustrated) Hetsu R phantom foam -

Claims (2)

[Claims] (1) Imaging means that uses an optical system to form a subject image on the imaging surface of a solid-state imaging device that has both a photoelectric conversion function and a charge transfer function, and generates a video signal corresponding to each pixel on the imaging surface. a shutter driving means for driving a lens shutter for controlling the exposure amount of the imaging surface; a focusing driving means for driving the optical system to focus the subject image on the imaging surface; a focus detection means for detecting that the system is arranged to be in focus; a recording means for recording the video signal onto a recording medium via a recording head; a disk motor for rotating the recording medium; servo lock detection means for detecting that the motor has reached steady rotation; head movement means for moving the recording head so as to have a plurality of tracks on the recording medium;
A constant voltage power supply that receives power from a battery and supplies a stable voltage to each circuit, a voltage detection means that detects whether this constant voltage power supply is outputting a predetermined voltage, and a voltage detection means that detects whether or not the constant voltage power supply outputs a predetermined voltage. means for operating the disk motor; and after a predetermined time has elapsed after starting the disk motor, operating the focus drive means and operating the shutter drive means in accordance with outputs of the servo lock detection means and the focus detection means. An electronic still camera characterized by being able to operate. (2) The electronic still camera according to claim 1, wherein the predetermined time is a time until the current flowing through the disk motor decreases to a predetermined value or less.