JP2592813B2 - Display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a display device.

[Conventional technology]

2. Description of the Related Art Conventionally, there are various imaging devices that can reproduce an imaging signal from an imaging device on a display device as shown in, for example, an electronic viewfinder of a video camera and know what kind of subject is actually being imaged. ing.

[Problems to be solved by the invention]

In the above-described image pickup apparatus, the power consumed by the image pickup device and the circuit for reproducing the image pickup signal from the image pickup device on the display device occupies a relatively large proportion in view of the power consumption of the entire device. If the power consumption of such a portion is large, the life of the power supply of the imaging apparatus is shortened, which is not preferable.

Accordingly, a first object of the present invention is to provide a display device with low power consumption.

It is another object of the present invention to provide a display device having a function of displaying the state of the power supply when the capability of the power supply is reduced, so that the state can be easily understood.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a display unit for displaying an image signal, a power supply unit, a unit for determining the capacity of the power supply unit, and the display unit according to a determination result of the determination unit. Control means for controlling, wherein the control means variably sets a display cycle in the display means in accordance with the result of the determination, and displays a still image which is a part of the moving image from a moving image display with a sufficient power supply capacity. It is intended to provide a display device characterized in that it can be changed step by step until the display.

[Action]

According to the present invention described above, the display state of the display unit is changed stepwise from a moving image to a still image which is a part of the moving image according to the level of the power supplied by the power supply unit.

〔Example〕

Hereinafter, a camera according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of a camera according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of the camera shown in FIG.

1 and 2, a camera body exterior 2, a photographing lens 2 for forming a subject image on a film held by a film pressure plate 10, and a reference numeral 3 for forming a subject image on a CCD chip 6. It is a liquid crystal viewfinder lens. In this embodiment, the taking lens 2 is a so-called auto-focus controlled lens which is automatically moved to a focus position by the distance measurement information obtained by the distance measurement unit 11 composed of 11A and 11B. Lens for fronter 3
Is a so-called pan-focus optical system that always forms a subject image on the CCD chip 6 in a sharp manner.

Reference numeral 4 denotes a low-pass filter which is provided on the CCD chip 6 and which cuts a high spatial frequency component of a subject image to prevent aliasing from being generated in a video signal obtained by the CCD chip 6. Reference numeral 5 denotes a CCD chip. A cover glass 6 for preventing dust from entering is the CCD chip, but in addition to using a CCD chip as in this embodiment, M
Of course, an OS-type solid-state image sensor, a solid-state image sensor called BASIS, or another type of image sensor may be used.

Reference numeral 7 denotes a circuit mounting unit which processes a signal of the CCD chip 6 and is provided with a circuit unit for driving the liquid crystal finder unit 8.
Denotes a liquid crystal finder provided above a finder of the camera. Although the liquid crystal is used in this embodiment, other display elements, for example, a functional optical element such as an ECD may be used.

Reference numeral 9 denotes a shutter for controlling whether or not to guide the light beam passing through the photographing lens onto the film, 10 denotes the film pressure plate, 11A, 11
B is a light projecting unit and a light receiving unit, both of which constitute a distance measuring unit. In this embodiment, a so-called active type distance measuring method is used, but a passive type distance measuring method may be used.

Reference numeral 12 denotes a photometer, and the shutter 9 is controlled based on photometric information obtained by the photometer.

Reference numeral 13 denotes a strobe for lighting when the luminance of the subject is lower than a predetermined value.

 14 is an objective lens for an optical finder, and 15 is an eyepiece for an optical finder.

In this embodiment, in addition to the liquid crystal finder section 8,
There is also an optical finder consisting of 4,15. Therefore, when performing framing, appropriate framing can be performed using an optical finder in the same manner as usual.

Reference numeral 16 denotes a release button. When the first step is pressed, photometric distance measurement and display by the liquid crystal viewfinder unit 8 are performed. When the second step is deeper than the first step, the lens barrel of the photographing lens 2 is driven and the shutter 9 is pressed. , And film winding is performed in this order.

Reference numeral 17 denotes a barrier opening / closing lever for opening / closing the barrier 18. By opening the barrier 18, power is supplied to each part of the camera.

Next, the electric circuit of the camera configured as above
This will be described with reference to the block diagram shown in FIG.

In FIG. 3, elements having the same functions as the elements shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 3, reference numeral 21 denotes a sequence control circuit for sequentially controlling the operation of each part of the camera, and 22 outputs to the sequence control circuit 21 data for controlling the shutter 6 in accordance with the output of the light receiving element provided in the photometry unit 12. A photometric circuit 25 drives the photographing lens 2 based on distance measurement information output from the distance measurement unit 11 by a lens barrel drive circuit.

26 is a shutter drive circuit for controlling the shutter 6 shown in FIG. 1 based on the output of the photometric circuit 22, and 28 is a shutter opening detection circuit for detecting the start of opening of the shutter and the fully opened state. 29
1 is a strobe circuit showing the circuit portion of the strobe shown as 13 in FIG. 1, 30 is an ISO detection circuit for detecting the DX code information of the film or ISO information of the film set manually, 31 is the CCD chip 6 and the CCD chip An imaging unit 32 composed of a driving circuit for driving the chip 6 is an image processing circuit for processing an imaging signal output from the imaging unit 31, and is provided to the A / D converter 35, the D / A converter 38, and the imaging unit 31. CCD chip 6 included
A control circuit 42 for controlling the drive timing of the switch and switches 36, 37 and 41 are configured.

Reference numeral 33 denotes a memory whose reading and writing are controlled by the sequence control circuit 21, and a switch 36 when writing is instructed from the sequence control circuit 21.
Then, the output of the A / D converter 35 is written via the switch 37, and when a read command is issued, the video signal stored in the memory is read via the switch 37.

Switches 36 and 37 are switches for switching between a still image display mode and a moving image display mode.
It is controlled by 21 control signals. Reference numeral 39 denotes a timer circuit, which is driven by the sequence control circuit 21. The switch 41 is a switch for turning on and off the display of the image on the display unit 8.

In other words, when the switch 36 is on and the switch 37 is switched to the a side while the switch 41 is on, the output of the imaging unit 31 is output from the A / D converter 35, the switches 36, a-c and D of the switch 37. The voltage is applied to the liquid crystal finder 8 via the / A converter 38 and the switch 41. Therefore the imaging unit
If 31 is driven continuously, the liquid crystal
Becomes the moving image display mode.

When the switch 36 is off and the switch 37 is switched to the b side, the output of the memory 33 is applied to the liquid crystal finder section 8 through the b-c D / A converter 38 and the switch 41 of the switch 37. You. Therefore, the still image stored in the memory 33 is displayed on the liquid crystal finder 8.

S-1 is a switch which is turned on when the shutter release button is pushed in the first stage, and S-2 is a switch which is turned on when the shutter release button is pushed in the second stage.

An oscillator 43 generates a reference clock for the operation of the sequence control circuit 21. 44 is a power supply battery, 45 is a power supply circuit for converting the voltage generated by the power supply battery 44 to a constant voltage, 46 is a difference amplifier that outputs a difference between the voltage V _DD output from the power supply circuit 45 and a predetermined voltage Vref generated by the battery 47. The predetermined voltage Vref is set to a voltage indicating that the imaging device is inoperable.

Reference numeral 48 denotes an A / D converter for A / D converting the output of the difference amplifier 46 and inputting it to the sequence control circuit 21.

Reference numeral 42 denotes the aforementioned control circuit, the details of which are shown in FIG. 4. In FIG. 4, reference numeral 42-1 denotes a maximum value detection circuit which detects the maximum value of the digital signal output from the A / D converter 35 and detects the maximum value. A maximum value detection circuit for holding a value for a predetermined time until a pulse φT described later is obtained, a window comparator 42-2, and a value held by the maximum value detection circuit 42-1 within a predetermined range, that is, a video signal It is determined whether or not the level of the video signal is at an appropriate level. If the level of the video signal is low, the signal at the terminal UP is set to "1", the accumulation time of the CCD chip 6 is extended, and the level of the video signal becomes high. Control the imaging unit 31 so that the video signal level is high
The DOWN signal is set to "1", the storage time of the CCD chip 6 is shortened, and the video section 31 is controlled so that the level of the video signal becomes low.

When the level of the video signal is appropriate, the signal at the terminal OK is set to “1”, and the imaging unit 31 is controlled so as not to change the accumulation time. Further, the signal of the terminal OK is connected to the preset counter 42-3, and the Q10 terminal of the counter 42-3 is changed to "Q10" until the level of the video signal becomes appropriate after the power is turned on by opening the barrier 18 where the POC pulse is applied. Inverter 42-4 as 1 "
The switch 41 is turned off by a signal of "0" through the switch, thereby prohibiting the liquid crystal finder 8 from performing display based on an inappropriate level signal.

Also, once the video signal becomes appropriate, the counter 42
-3 is reset and the output of the terminal Q10 becomes "0". Accordingly, the switch 41 is turned on by the inverted output "1" via the inverter 42-4, and the display on the liquid crystal finder 8 is performed.

Note until also 10 pulse counts pulses phi _T, which will be described later, as was the signal "0" level of the pin OK after changing the level of the video signal after the video signal becomes once appropriate in this embodiment The output of the terminal Q10 of the counter 42-3 remains "0". Therefore, the switch 41 is kept on by the inverted output "1" via the inverter 42-4, and the display of the liquid crystal finder unit 8 continues to be performed.

Therefore, the liquid crystal finder unit 8 does not perform display until the video signal level becomes appropriate after the barrier 18 is opened,
After the display of the liquid crystal finder unit 8 is performed after the level becomes appropriate, the liquid crystal finder unit 8 is displayed only when the luminance of the subject is too bright or too dark to control the CCD accumulation time. Since the display is stopped, the display of the liquid crystal finder section 8 is prevented from flickering. 10 pulse counts phi _T in Note embodiment, i.e. prohibits the display of the liquid crystal Fuainda portion 8 when be changed 10 times the accumulation time based on the signal read out 10 times video signal from CCD6 video signal is not appropriate However, other means, such as a photometric circuit,
Alternatively, the detection may be performed based on the output of 22.

In addition, in the control circuit 42 shown in FIG. 4, the accumulation time of the CCD chip 6 is controlled based on the level of the video signal. However, instead of the video signal, the output of the photometric circuit is indicated as shown by a dotted line in FIG. The accumulation time may be controlled. In such a case, there is an effect that the circuit shown in FIG. 4 becomes unnecessary and the configuration is simplified.

Next, the configuration of the CCD chip 6 used in the image pickup section 31 and a drive circuit for driving the chip 6 will be described in detail with reference to FIG.

FIG. 5 is a diagram showing a configuration of the CCD chip 6 and a drive circuit for driving the chip 6. In FIG. 5, reference numeral 50 denotes a photosensitive portion for forming a pixel, which is arranged in a matrix such as 500 in the vertical direction and 500 in the horizontal direction.

The signal accumulated in the photosensitive section 50 is read by a read gate 52.
Is transferred to the vertical transfer CCD 51 via the
It is read out sequentially by 56.

That applying a read pulse phi _T the read gate,
By opening the gate, the signal stored in the photosensitive unit 50 is transferred to the vertical transfer CCD 51. Vertical transfer CCD51
Is driven by a vertical transfer pulse φ _V. Each time one pulse is applied, a horizontal transfer pulse φ _H equal to the number of pixels in the horizontal direction is applied to the horizontal transfer CCD 56, and a signal accumulated in the photosensitive portion is applied. They are sequentially read out and output to the A / D converter 35.

Numeral 53 denotes a drain gate, which is opened by applying a clear pulse φ _CL , and the signal accumulated in the photosensitive section 50 flows into the drain 57 and is cleared. Therefore, the time from applying the pulse φ _CL to the drain gate 53 to clear the photosensitive section 50 to applying the pulse φ _T to the read gate 52 and reading the signal stored in the photosensitive section is CCD6.
Storage time.

Reference numeral 58 denotes a drive circuit that outputs the pulses φ _CL , φ _T , φ _V , and φ _H described above, according to the signal output from the control circuit 42, that is, according to the level of the video signal output from the imaging unit 31. By controlling the output timing of the clear pulse φ _CL , the accumulation time of the photosensitive section 50 is controlled so that the level of the video signal does not overflow.

The pulses generated by the drive circuit 58 are shown in the time chart of FIG.

In FIG. 6, AC indicates the level of the signal stored in the photosensitive unit 50, and φ _CL , φ _T , φ _H , and φ _V indicate the generation timing of the aforementioned pulse. Note that both φ _H and φ _V are continuously generated in the interval T at which the read pulse φ _T is output. Although they are pulses and have significantly different frequencies from each other, both pulses are shown as similar pulses in FIG. 6 for simplicity.

Sixth time accumulation time of the photosensitive unit 50 is represented by t ₁ shown in t ₂ in Figure is a period abandon even signals stored accumulated by the clear pulse phi _CL signal to the drain.

Here, the generation timing of the clear pulse φ _CL will be described with reference to FIG. Drive circuit 58 to lengthen the shorter t ₂ where t ₁ is high level of the video signal results overexposed read the video signal shown as _{l-1, (t 1 +} t 2 = T is constant) video in underexposure level signal to adjust the timing of the clear signal as if a longer t ₁ low. Therefore, the l-th exposure can be controlled to be properly adjusted.

Therefore, according to the present embodiment, a video signal of an appropriate level is obtained by controlling the accumulation time of the CCD chip 6, so that the finder optical system constituted by the finder lens 3 is provided in accordance with the luminance of the subject. This has the effect that it is not necessary to provide a stop whose aperture is controlled.

Next, the operation of the embodiment configured as described above will be described in the seventh.
This will be described with reference to the flowchart of FIG.

First, even if the barrier 18 is opened, the release button 16 of the camera is not pressed down, and nothing is displayed on the liquid crystal finder unit 8 when the switches S-1 and S-2 are turned off (click on # -1). return).

Next, when the release button is pushed down to the first stroke, the switch S-1 is closed, the photometry circuit 22 is operated by the sequence control circuit 21, the brightness of the subject is measured, and the timer circuit 39 is reset (#-).
2). Here, when the photometric value is equal to or more than the predetermined value, the switch 37 is turned to the a side, the switch 36 is turned on, and the switch 41 is turned on (# -4). At this point, the output of the A / D converter 48 is captured, and if the output of the A / D converter 48 is equal to or more than a predetermined value, that is, if a sufficient driving voltage is applied to the imaging device, the #- Go to 5. When the output of the A / D converter 48 is equal to or less than a predetermined value and is equal to or greater than 0, that is, when the voltage applied to the imaging device is near the minimum operating voltage, the operation proceeds to # -22. If the output of the / D converter 48 is 0 or less, the flow branches to # -23 (# -21).

If the voltage applied to the imaging device is near the minimum operating voltage, the drive frequency of the imaging unit 31 and the liquid crystal finder unit 8 is halved in # -22. This is oscillator 43
This is done by dividing the block input from by two. Since the power consumption of the CCD and the liquid crystal finder provided in the imaging unit 31 increases as the driving frequency increases, the power consumption can be reduced by halving the driving frequency in this step. .

In this case, the display cycle of the liquid crystal viewfinder 8 is 1/2 of that in the normal case, but it can be used.

In the present embodiment, the driving frequency is set to 1/2,
However, the power consumption can be reduced if the driving frequency is made slower than in the normal case.

Further, according to the present embodiment, when the power supply capability is reduced, the display of the liquid crystal finder becomes intermittent, so that the user can reduce the supply capability without providing a special display unit for displaying the power supply status. You can know.

If the voltage applied to the image pickup apparatus falls below the operable voltage, a warning is issued in the liquid crystal finder section 8 (# -23), and the flow returns to # -2 to inhibit the photographing operation. Sequence control circuit 21 to imaging unit
A trigger signal is applied to the drive circuit 31 and the drive circuit 58 shown in FIG.
Starts operation, and the liquid crystal finder unit 8 also performs display (# -5). That is, the clear pulse φ _CL , the read pulse φ _{T the} vertical transfer pulse φ _V , and the horizontal transfer pulse φ shown in FIG.
_H are sequentially output, and when the video signal obtained by the imaging unit 31 has reached an appropriate level, the liquid crystal display unit 8 displays a moving image mode. When the photometric value is equal to or less than the predetermined value, the strobe circuit 29 operates and charging is started. However, unlike the flow shown in the figure, by jumping the flow from # -3 to # -1, the sequence control circuit is started. It is also possible to prohibit the display on the liquid crystal finder 8 when the brightness is low so that the trigger signal is not applied from 21 to the imaging unit 31.

As described above, when the switch S-1 is closed and the photometric value of the photometric circuit 22 is equal to or greater than the predetermined value and the power supply voltage _VDD is equal to or greater than the operable voltage, the drive circuit included in the imaging unit 31 as described above.
58 travels on its own to generate pulses φ _L , φ _T , φ _V , φ _H and a moving image is displayed on the liquid crystal finder section 8. In this state, the output of the control circuit 42 is output as described above. Controls the accumulation time of the imaging unit 31 so that the level of the video signal output from the imaging unit 31 becomes appropriate.

Next, it is determined whether or not the switch S-2 is turned on (# -6). When the switch S-2 is turned on, the flow proceeds to # -9, and
A shooting operation is performed. On the other hand, when the predetermined time has elapsed without the switch S-2 being turned on, the display of the liquid crystal finder section 8 is temporarily stopped (# -8), and the flow returns to # -1. Therefore, when a predetermined time elapses after the switch S-1 is turned on, the display on the liquid crystal finder section 8 is automatically stopped, and wasteful consumption of the power supply battery is suppressed.

As a method of stopping the display, the driving of the imaging unit 31 may be stopped, the driving of the imaging unit 31 may be performed, and the driving of the liquid crystal finder unit 8 may be stopped. The driving of both may be stopped.
Alternatively, the switch 41 may be turned off. The predetermined time in the above-mentioned # -7 is a sufficient time necessary for the photographer to perform framing (for example, about 5 to 10 images).
You can do it.

When the release button is pushed down to the second stage and the switch S-2 is turned on within the predetermined time, the lens barrel is driven to the in-focus position based on the distance measurement information of the distance measurement unit 11 (#-
9) Further, the display of the finder section 8 is temporarily stopped (# -10), and then the shutter 9 is driven to open (# -11).

Next, a write pulse is applied to the memory 33 (#-
12) CCD in synchronization with the read pulse phi _T shown in FIG. 6
The video signal read from the chip 6 is written to the memory 33 via the switch 36.

Note that such writing is performed first by CCD6 after the shutter opens.
Is performed on the signal stored in.

Next, the shutter 9 is closed (# -13), the film is wound up by a film winding circuit (not shown), a readout pulse is applied to the memory 33, the switch 37 is switched to the b side, and the liquid crystal finder section 8 has the memory. The video stored in 33 is reproduced, that is, a still image display mode is set (# -14).

Also, in this step # -14, the operation of the imaging unit 31 may be stopped, that is, φ _V , φ _H , φ _T , and φ _CL may not be generated.

As can be seen from the above description, the image reproduced on the liquid crystal display unit 8 is an image synchronized with the start of the opening of the shutter. ing. Therefore, immediately after the photographing is completed, the photographer is automatically displayed on the liquid crystal finder 8 as a still image. Looking at this confirmation video, it is possible to check the shutter and framing on the spot. Therefore, if you are dissatisfied, you will be able to take another shot on the spot, and even for people other than the photographer,
The effect is that the framing of the taken picture can be explained on the spot.

The lapse of time since switching to the still image display mode at # -14 is also measured by a timer, and if the switch S-1 does not turn on again within a predetermined time, the display on the liquid crystal finder unit 8 is automatically turned on. The operation is stopped, that is, the still image display mode is stopped (# -15, # = 16).

This is a power saving measure similar to the case of stopping the moving image display mode by the timer described in # -1 to # -8. It is sufficient to use a sufficient time as necessary to confirm the condition.

On the other hand, if the photographer presses the release button 16 again to perform the next photographing before the predetermined time elapses, the flow is # when the switch S-1 is turned on by pressing the first step.
The flow branches from -15 to # -2, photometry is performed in the same manner as described above, and then distance measurement and switching to the moving image display mode are performed. The subsequent operation is as described above.

It is a matter of course that a step of turning off the power may be provided instead of stopping the display at # -8 and # -17 shown in FIG. 7 (a). In this case, the power is automatically turned off after a lapse of a predetermined time without operating the switch S-1 or the switch S-2 from the moving image display mode or the still image display mode. It has the effect of becoming.

Next, the timing at which the video signal is written to the memory 33 at # -12 will be described in detail with reference to FIG.

In FIG. 8, (a) shows the opening waveform of the shutter 9 which is opened at # -10 and the operation starts, and (b) is the shutter opening detection circuit 28 to the sequence control circuit 21.
(C) shows a write pulse applied from the sequence control circuit 21 to the memory 33, and (d) shows a clear pulse φ _CL and a read pulse φ _T explained in FIG. Indicates the timing of application to the CCD chip 6. As is clear from FIG. 8 (a), the timing at which the write pulse (c) is applied at # -12 after the shutter opening is detected by the shutter opening detecting circuit 28 (FIG. 8 (a) t). ₀ ) First read pulse φ _T
There the timing applied (Figure 8 (a) the timing shown in t _1). Video signal written in this case the memory 33 is stored in CCD in period shown in Figure 8 (a) t _2.

Further, the shutter opening detection circuit 28 is not a circuit for detecting from the start of the opening of the shutter to the closing of the shutter, and is a circuit for detecting the timing when the shutter has reached the maximum opening, so that the timing shown in FIG. , A write pulse (c) can be applied.

Shown in CCD chip video signal obtained by 6 (Figure 8 (b) t ₂ at the time when the shutter is fully opened in response to the words shutters open detection circuit 28 by shutter first read pulse φ from the largest opening _T In other words, the video signal closest to the image exposed on the film is obtained in the memory 33.

8 (a) and 8 (b), the drive pulse applied to the CCD chip 6 is output from the drive circuit 58 by self-running for a predetermined period, but is shown in FIGS. 8 (a) and 8 (b). If the drive circuit 58 is reset in response to the shutter opening detection pulse (b), a video signal accurately synchronized with the start of the opening of the shutter or the maximum opening of the shutter can be obtained.

 This will be described with reference to FIGS. 8 (c) and 8 (d).

In FIG. 8 (c), the drive circuit 58 is reset in response to the detection of the opening of the shutter by the shutter opening detection circuit 28, and the clear pulse φ _CL is output from the circuit 58 (FIG. 8 (c) T ₀ ). 8) A read pulse φ _T output after a storage time t ₂ , in which the signal stored in the photosensitive unit 50 is once cleared and a video signal of an appropriate level is controlled in advance so as to be obtained (FIG. 8). (c) t ₁ to the video signal memory 3 stored in the CCD chip 6 in the period t ₂ and outputs in synchronization with the write pulse (c) the timing) showing
Written to 3.

Therefore, in the case shown in FIG. 8C, a video signal accurately synchronized with the detection of the opening start of the shutter is written into the memory 33.

Figure 8 CCD in the period t ₂ of the drive circuit reset diagram in accordance with the detected maximum opening of shutters of maximum opening of the shutters by shutter opening detection circuit 28 in (d)
The video signal stored in the chip 6 is written to the memory 33.

In the above-described embodiment, the video signal obtained from the CCD chip 6 is written into the memory 33 in response to the detection of the maximum aperture of the shutter, but the video signal obtained from the CCD chip 6 is written in response to the closing signal of the shutter. The data may be written to the memory 33.

The shutter maximum aperture eighth instead of using the detected timing diagram (a) ~ the timing shown in (d) of the t _4, i.e. shutter opening the way to obtain a signal, for example, synchronous signal for synchronizing with the strobe ( to the same manner as described above the memory 33 in accordance with a timing corresponding to to) generated at the timing of Fig. 8 t ₄ it may be as writing the video signal.

In this case, a video signal obtained by the CCD chip 6 is written to the memory 33 at substantially the same timing as the image exposed on the film.

In addition, instead of using the timing at which the maximum opening of the shutter is detected, the video signal is written to the memory 33 using the timing at which the state of the switch S-2 switches according to the pressing of the release button 16 in the second stage. It may be.

Next, a description will be given of a flow when flash photography is performed because the brightness of the subject is low.

At the time of flash photography, a sequence exactly the same as that described with reference to FIG. 7 proceeds, but the control performed at # -12, that is, the accumulation timing of the CCD chip 6, is different.

That is, when the flash is used to change the timing of generation of the clear pulse phi _CL as described above for using the Figure 6 CC
The video signal read from the D chip 6 cannot be properly controlled.

Accordingly, in the present embodiment, as will be described below with reference to FIG. 8 (e), in the case of flash photography, the video signal accumulated by the CCD chip 6 is written to the memory 33 when the flash emission is not performed. I have to.

Figure 8 in (e) (e) represents the light emission timing of the strobe 13, is synchronized with the sync signal shown in t _4.
Note that the light emission time of the strobe 13 is much shorter than the time when the shutter is open.

In Figure 8 (e), shutter strobe 13 emits light at the timing shown in t ₄ opened.

From the sequence control circuit 21 after the elapse period from synchro signal is generated until the light emission of the strobe 13 is completed (FIG. 8 (e) after the elapse of period shown in t ₅₎ driving circuit 58 the circuit 58 to reset the The clear pulse φ _CL is output, the signal stored in the photosensitive unit 50 is cleared once, and the storage time is controlled in advance so that a video signal of an appropriate level is obtained.
video signal stored in the CCD chip 6 in the period t ₂ is written into the memory 33 by in synchronization with the read pulse phi _T outputted after t ₂ outputs a write pulse (c).

Therefore, according to this embodiment, the image written in the memory 33 as described above does not necessarily receive any strobe light irradiation,
The image is illuminated only by natural light. Therefore, considering that the image to be captured on the film is an image obtained by flash irradiation, the image confirmation becomes insufficient. On the other hand, when this method is used, the accumulation time of the CCD chip 6 is controlled even during flash shooting. Since it can be performed by a method using a clear pulse as in natural light imaging, it is not necessary to add an aperture mechanism to a finder optical system provided in front of the CCD chip 6 for flash photography, which is advantageous in terms of cost. (Because the CCD has a very high sensitivity even on the low-brightness side, even if a strobe is required for film exposure, it is possible to capture images using only natural light.) Also, for flash photography, an aperture mechanism is designed for the liquid crystal viewfinder lens 3. The aperture may be appropriately changed according to distance information from the distance measuring device. (If the distance is far, open the aperture, if it is close, narrow the aperture.) That is, the subject distance is d,
The aperture may be changed to F∝C / d (C is a constant) as F.

In the above description of the embodiment, as shown in the flowchart of FIG. 7, when the switch S-1 is turned on by pressing the release button in the second stage, a still image is displayed on the liquid crystal finder section 8, and the switch is left as it is. If the predetermined time has elapsed without turning on either S-1 or S-2, the flow branches from # -15 to # -17, and the display is stopped by # -17. By configuring the flow chart to branch to # -4, in such a case, it is possible to automatically switch from the still image display mode to the moving image display mode.

In the above embodiment, when the power supply voltage is low, the power consumption can be reduced by lowering the driving frequency of the imaging unit 31 and the liquid crystal viewfinder unit 8. When the switch S-1 is turned on from off, the imaging unit 31 is driven. When the accumulation time of the imaging unit 31 is controlled to be appropriate, the video signal of the imaging unit is written to the memory 33, and then the imaging is performed. An embodiment in which power consumption is kept low by stopping the driving of the unit will be described. Further, in this embodiment, an embodiment is disclosed in which the power consumption of the liquid crystal finder 8 is minimized by driving the liquid crystal finder 8 only while the switch S-1 is on.

Next, the operation of this embodiment will be described. In this embodiment, the sequence control circuit 21 executes the flowchart shown in FIG. 7 (b), and the other configuration is the same as that of the previous embodiment. In the flowchart shown in FIG. 7 (b), steps having the same functions as those in the flowchart shown in FIG. 7 (a) are denoted by the same reference numerals, and description thereof is omitted.

Signal input from the A / D converter 48 determines whether positive at either the # -25 when switch S-1 is turned on in such an embodiment, operation of the power supply voltage V _DD imaging apparatus If the voltage is below the allowable voltage, a warning is issued immediately (# -2
6).

In step # -5, the image pickup unit 31 is driven. When it is detected that the signal from the OK terminal of the window comparator 42-2 shown in FIG. Then, a write pulse is applied to the memory 33 (# -30), and a signal from the imaging unit 31 is written into the memory 33. Next, switch S
The state of -1 is detected again (# -32), and if it is on, the process proceeds to # -33. Here, if the output voltage V _DD of the power supply circuit is just before the operable voltage, a read pulse is sent to the memory 33. Then, the switch 37 is connected to the b side to drive the liquid crystal finder section 8 (# -36). In # -36, the imaging unit 31
Also stop.

If the switch S-1 is not on, the driving of the liquid crystal finder section 8 is stopped (S-34). Therefore, in this embodiment, when the switch S-1 is turned off, the driving of the liquid crystal finder unit 8 is immediately stopped, and the power consumption can be reduced as compared with the embodiment shown in FIG.

When the output of the A / D converter 48 indicates a voltage operable sufficiently for the image pickup device at # -33, the liquid crystal
Is started (# -35). Before executing this step, the switch 37 is already connected to the a side at # -4, and
Since the switches 36 and 41 are turned on, a moving image is displayed on the liquid crystal finder unit 8 by executing # -35.

Further, in this embodiment, when the output of the A / D converter 48 is just before the operable voltage of the imaging device, a write pulse is generated in # -36 and the imaging signal from the imaging unit 31 is written to the memory 33. Since the driving of the imaging unit 31 is stopped, power consumption in the imaging unit can be minimized.

After the switch S-2 is turned on and the flow branches from # -6 to # -9, the same operation as described in the first embodiment is performed. If switch S-1 has not been turned on
The output of the A / D converter 48 is detected (# -40).

If the power supply voltage is not sufficient at # -40, the flow branches to # -17, where the driving of the liquid crystal finder section 8 is stopped immediately, and the display is stopped.

Therefore, in this embodiment, when the power supply voltage is almost at the limit of the operable voltage, the switch S-2 is turned on, and the liquid crystal finder 8 is displayed only while the switch S-1 is turned on after photographing. The life of the power supply can be lengthened as much as possible.

If the switch S-2 is not turned on in # -6 and the predetermined time counted by the reset timer has not elapsed in # -2, if the power supply voltage is sufficient, # -2 If the power supply voltage is sufficient, the flow branches to # -32. Therefore, as described above, when the power supply voltage is not sufficient, the image written in the memory 33 is displayed as a still image on the liquid crystal finder unit 8 while the operation of the imaging unit 31 is stopped in # -36.

In the above-described embodiment of the present invention, the circuit for determining the power supply voltage V _DD output from the power supply circuit is used as a means for determining the capacity of the power supply, but other types of power supply, for example, whether the power supply is a commercial power supply or a battery. Of course, it may be a circuit for determining whether or not there is.

In the embodiment of the present invention described above, the sequence control circuit 21 executes # 21 and # 22 shown in FIG. 7 (a) as control means for controlling the image display cycle in accordance with the determination result of the determination means. However, various methods can be considered for controlling the display cycle as described above.

In the embodiment of the present invention, as a control means for selecting and displaying any of a moving image and a still image on the electro-optical element according to the result of the determination by the determination means, the control means # -28 to # -28 shown in FIG.
The sequence control circuit 21 executes # -36.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, power consumption in the display device can be suppressed, and the life of the power supply can be extended.

Moreover, according to the present invention, the user can check the power supply state without providing a special display unit.

[Brief description of the drawings]

FIG. 1 is a perspective view of a camera according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line AA of the camera shown in FIG. 1, FIG. 5 is a block diagram showing details of the control circuit 42 shown in FIG. 3, FIG. 5 is a diagram showing the configuration of the CCD chip 6 shown in FIG. 1, and a drive circuit for driving the chip 6, FIG. 7 is a time chart showing pulses generated by the drive circuit 58 shown in FIG. 5, FIGS. 7 (a) and 7 (b) are flow charts showing the operation of the sequence control circuit 21 shown in FIG. 3, and FIG. a) to (e) are time charts showing the timing at which the video signal obtained from the CCD chip 6 is written into the memory 33. 3 Liquid crystal display unit 6 CCD chip 21 Sequence control circuit 58 Drive circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideo Inogari 770 Shimonoge, Takatsu-ku, Kawasaki Canon Inc. Tamagawa Works (72) Inventor Makoto Miyawaki 770 Shimonoge, Takatsu-ku Kawasaki City Canon Inc. Tamagawa Works (72) Inventor Takushi Ikeda 770 Shimonoge, Takatsu-ku, Kawasaki City Inside the Tamagawa Works of Canon Inc. (56) References JP-A-60-33787 (JP, A) JP-A-56-48765 (JP, A) JP-A 61-184976 (JP, A) Japanese Utility Model Showa 60-112150 (JP, U) Japanese Utility Model Showa 55-135577 (JP, U)

Claims (1)

(57) [Claims] A display means for displaying an image signal; a power supply means; a means for determining a capacity of the power supply means; and a control means for controlling the display means in accordance with a determination result of the determination means. The control unit variably sets a display cycle in the display unit according to the determination result, and gradually changes from a moving image display with a sufficient power supply capacity to a still image display which is a part of the moving image. A display device, comprising: