JP2000039656A - Digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set a photographing lens at a housing position when a power source is turned off by monitoring the voltage of the power source and moving the photographing lens to the housing position before the voltage of the power source becomes the minimum voltage required for moving the photographing lens to the housing position based on the monitored result. SOLUTION: When the power source is turned on and a power source switch PS is depressed, it is detected by an overall control part 211. By the control part 211, the energizing of blocks which are not required for driving a zoom motor M1 is immediately cut off and the motor M1 is driven through a zoom motor driving circuit 215 for a prescribed time required for returning the front group of a zoom lens to the housing position. Besides, the voltage monitoring circuit W of the power source E is connected to the control part 211. Then, when the voltage of the power source is lowered to 3.7 V, the energizing of all the blocks which are not required for driving the motor M1 is cut off. Thereafter, the power source is perfectly turned off after the photographing lens is moved to the housing position by driving the motor M1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital camera.

[0002]

2. Description of the Related Art In recent years, an image sensor, a CPU (central proc
With the spread and development of semiconductor technologies such as essing units and memories, CCD (charge)
2. Description of the Related Art A so-called digital camera that converts a scene into an image signal using an imaging device such as a coupled device and records the image signal on a flash memory after performing processing by a CPU has become widespread.

In a digital camera, a so-called collapsible lens, in which a photographic lens is housed in a body when the camera is carried and jumps out to a predetermined position during photographing, has been used as in a conventional silver halide camera. I have. In particular, as the number of pixels of the image sensor increases, the optical performance required of the photographing lens increases, and as the lens configuration becomes more complicated, the overall length of the lens tends to be longer. Adopting this method has the advantage of not impairing portability.

In a retractable digital camera, the photographing lens moves from a storage position to a predetermined focusable position when the power is turned on, and moves from a focusable position to a storage position when the power is turned off. I will be.

[0005]

Most of the conventional digital cameras are driven by a battery in order to meet the demand for portability. However, since many parts consume power, some measures have been taken to suppress the consumption of the battery. When the power is exhausted, control is performed so that the energization of each circuit is immediately cut off. Each floor will be in the same state as when the power is turned off by shutting off the power supply, but only the retractable digital camera's taking lens will return to the storage position and will be in the same state as when the power is turned off for the first time. Become.

However, there has been no study on such control of the taking lens at the time of power consumption. Therefore, power is lost, the taking lens cannot be moved to the housing position, and the taking lens protrudes from the main body even when the power is turned off, causing damage to the taking lens and portability. There was a problem that was bad.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a digital camera in which, even when the power is turned off due to power consumption, the photographing lens is in the housing position when the power is turned off.

[0008]

According to a first aspect of the present invention, an image of a subject is formed on an image sensor by a photographing lens, and the image of the subject is converted to an electric signal by the image sensor. In a digital camera equipped with a photographing lens that is in a storage position when the power is off and is in a focusable position when the power is on, a monitoring unit that monitors a power supply voltage; and Control means for moving the photographing lens to the accommodation position before the power supply voltage becomes the minimum voltage necessary to move the imaging lens to the accommodation position based on the monitoring result. I do.

In the above configuration, no power is lost when the photographing lens is not housed in the housing position. Therefore, even when the power is turned off due to power consumption instead of the user's operation, the photographic lens is always in the housed position when the power is turned off.

According to a second aspect of the present invention, a subject image is formed on an image sensor by a photographing lens, and the subject image is converted into an electric signal by the image sensor. Monitoring means for monitoring a power supply voltage in a digital camera comprising: a photographing lens which is in a focusable position when the power is turned on; and a display means for displaying a photographed image based on the electric signal. And a control means for issuing a warning before the power supply voltage reaches a minimum voltage necessary for moving the taking lens to the accommodation position based on a monitoring result of the means.

In the above configuration, a warning is issued before the power supply voltage reaches the minimum voltage required for the photographic lens to return to the housing position. Therefore, the user operates the power button based on the warning. Then, when the power is turned off, the photographing lens is moved to the accommodation position in the same manner as the operation according to the normal power-off instruction.

According to a third aspect of the present invention, in the digital camera according to the second aspect, the warning is displayed by the display means, and the control means supplies power to the display means after the warning is displayed. Is shut off. In such a configuration, it is desirable that all of the circuits other than the display unit, which are not related to the driving of the photographing lens, be cut off. By doing so, the power consumption after the warning is displayed is extremely reduced.

According to a fourth aspect of the present invention, in the digital camera according to the second or third aspect, the control means includes:
After the warning, when the user turns off the power by operating the operation unit, the photographing lens is moved to the housing position.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a digital camera according to an embodiment of the present invention will be described with reference to the drawings. 1 to 3 are external views of the digital camera of the present embodiment. As shown in FIGS. 1 to 3, the digital camera 1 includes a box-shaped camera body 2 and a rectangular parallelepiped imaging unit 3. The digital camera 1 according to the present embodiment has an LCD display unit 10 (see FIG. 2) for confirming a shooting scene or allowing a photographed image to be immediately confirmed on the spot.
It has.

Hereinafter, in the camera body 2, the surface on which the LCD display unit 10 is formed is the back surface, the back surface is the front surface, the surface on which the operation members such as the shutter button 9 are formed is the upper surface, and the back surface is the rear surface. The surface is the bottom. FIG. 1 is a front view in which the bottom of the drawing is the bottom, FIG. 2 is a rear view in which the bottom of the drawing is the bottom, and FIG. 3 is a bottom view in which the bottom of the drawing is the front.
Of the two surfaces surrounded by the front surface, the back surface, the top surface, and the bottom surface, the surface located on the right side in FIG. 1 is the imaging unit connection surface, and the other surface located on the left side is the holding surface (generally, this surface). To hold the camera against the palm of your hand).

First, the components of the camera body 2 will be described. On the front of the camera body 2, as shown in FIG.
A grip part 4 is provided at an appropriate position on the left end, and a built-in flash 5 is provided at an appropriate upper part. As shown in FIG. 2, an LCD display section 10 for displaying a captured image on a monitor (corresponding to a viewfinder) and displaying and reproducing a recorded image is provided substantially at the center of the left end of the camera body 2 as shown in FIG. Have been.

A compression ratio setting slide switch 12 is provided below the LCD display unit 10. FL (flash) from the left side above the LCD display unit 10
A mode setting switch 11, a power switch PS that switches on / off each time the button is pressed, and a shooting / playback mode setting switch 14 are provided. In the right position, the quad switch Z
Is provided.

The digital camera 1 has an "automatic flash mode" in which the built-in flash 5 is automatically fired in accordance with the subject brightness as a mode relating to flash emission, and a "forced" mode in which the built-in flash 5 is forcibly fired regardless of the subject brightness. A flash mode and a flash inhibition mode for inhibiting the flash of the built-in flash 5 are provided. Each time the FL mode setting switch 11 is pressed, each of the automatic flash mode, the forced flash mode, and the flash disabled mode is cyclically switched. Switches to
One of the modes is selected and set.

The digital camera 1 is configured so that the compression ratio K of image data recorded on a memory card, which will be described later, can be selected and set at two values, 1/8 and 1/20. For example, sliding the compression ratio setting switch 12 to the right sets the compression ratio K = 1/8, and sliding to the left sets the compression ratio K = 1/20. In the present embodiment, two types of compression ratios K can be selectively set. However, three or more types of compression ratios K may be selectively set.

The shooting / playback mode setting switch 14 is
This is for switching between a “photographing mode” and a “reproduction mode”. The photographing mode is a mode for photographing, and the reproduction mode is a mode for reproducing and displaying a photographed image recorded on a memory card on the LCD display unit 10. The shooting / playback mode setting switch 14 also includes a two-contact slide switch. For example, sliding to the right sets the playback mode, and sliding to the left sets the shooting mode.

The quad switch Z has four buttons Z1, Z
2, Z3 and Z4. When the button Z1 is pressed, a zoom lens of the imaging unit 3 described later moves in the wide direction, and when the button Z2 is pressed, the zoom lens moves in the tele direction. When the button Z3 is pressed, the exposure is corrected in the plus direction, and when the button Z4 is pressed, the exposure is corrected in the minus direction. Even when the apparent brightness of the subject changes due to zooming, the optimum exposure value can be manually set by pressing the exposure correction buttons Z3 and Z4. Zoom buttons Z1, Z2 and exposure compensation buttons Z3, Z
4 is configured as one quadruple switch Z,
These operations can be performed with one hand, and the operability is good.

As shown in FIG. 3, a battery loading chamber 18 and a card loading chamber 17 are provided on the bottom surface of the camera body 2, and the loading ports of the loading chambers 16 and 17 have clamshell type lids 15. To be closed. In FIG. 1, the lid 15 is open, and in FIGS. 2 and 3, it is closed. The lid 15 opens and closes in a direction indicated by an arrow 15a in FIG.

The digital camera 1 in the present embodiment is
A power supply battery E, which is formed by connecting four AA batteries E1 to E4 in series, is used as a drive source, and the battery loading chamber 18 is configured to accommodate the four batteries. The card loading chamber 17 is configured to store a memory card 8 for recording compressed image data. As shown in FIG. 1, the memory card 8 is inserted and removed in a direction parallel to the front and back surfaces of the camera body 2 (the direction of the arrow 8a).

As shown in FIG. 1 and FIG. 2, on the upper surface of the camera body 2, switches 6 and 7 for frame advance when reproducing a recorded image in the reproduction mode are provided substantially at the center. The switch 6 is a switch (hereinafter, referred to as an UP switch) for advancing the recorded image in the direction in which the frame number increases (the direction of the photographing order), and the switch 7 operates in the direction in which the frame number decreases. This is a switch for frame advance (hereinafter referred to as a DOWN switch). An erasing switch D for erasing an image recorded on the memory card 8 is provided on the left side of the DOWN switch 7 as viewed from the rear side (FIG. 2), and a shutter button 9 is provided on the right side of the UP switch 6. .

FIGS. 1 and 2 show the holding surface of the camera body 2.
As shown in FIG. 1, a connection terminal 13 to which a personal computer is externally connected is provided. The camera body 2 mainly performs predetermined signal processing on the image signal captured by the imaging unit 3, and then performs processing such as display on the LCD display unit 10, recording on the memory card 8, and transfer to a personal computer. Is performed.

Next, the imaging section 3 will be described. The imaging unit 3 has a collapsible photographing lens, and is detachable from a photographing unit connection surface of the camera body 2. The image pickup unit 3 is configured so that the position of the entrance window 301a (light from which the light enters the photographing lens) can be rotated by 180 degrees from the front side to the rear side through the upper side when mounted on the camera body 2. Have been. FIG.
3 to 3 show a state in which the entrance window 301a is on the front side.

As shown in FIGS. 1 to 3, the imaging section 3 has a length substantially equal to the length of the camera body 2 in the height direction, and the width of the camera body 2. It is in the shape of a vertically long rectangular parallelepiped having a slightly larger dimension than that of. Figure 1,
As shown in FIG. 2, the photographing unit 3 has well-known structures such as an entrance window 301a of a photographing lens, a dimming sensor 305 that receives flash light reflected from a subject, and a silver halide lens shutter camera. An optical viewfinder 31 is provided.

FIG. 4 shows a schematic configuration of the inside of the image pickup section 3. 4A shows a state in which the photographing lens 301 is housed when the power is turned off, and FIG. 4B shows a state in which the photographing lens 301 is moved to a predetermined position where focusing is possible when the power is turned on. Show. When the power is turned on, the taking lens 301 moves from the state (a) to the state (b). In the present embodiment, the predetermined position is the wide end. FIG.
In the figure, the upper side of the paper is the front side of the camera body, and the lower side is the back side of the camera body.

The imaging unit 3 includes a front group 3011 and a rear group 3012
An imaging circuit 3 including a photographing lens 301 which is a zoom lens and a CCD color area sensor 303 disposed at an appropriate position behind (backward to) the photographing lens 301.
02, and a dimming circuit 304 including a dimming sensor 305 (see FIG. 1) that receives the reflected light of the flash light from the subject.
Is provided. A zoom motor M1 for changing the zoom ratio of the photographing lens 301 and moving the lens between the accommodation position and a predetermined position, and a motor M2 for performing focusing.
Are provided.

When the taking lens 301 is stored,
As shown in FIG. 4A, the front group 3011 is set so as to be located at a position closer to the rear group 3012 than a predetermined focusable position (accommodation position), and by pressing the power button,
The front lens group 3011 is a so-called collapsible photographic lens in which the front group 3011 moves forward as shown in FIG. This makes it possible to use a zoom lens that is long in the optical axis direction without increasing the width of the digital camera 1.
When the power is turned on, it is set so as to be located at the wide end of the taking lens 301, and when the power is turned off, it is set at the accommodation position. The lens movement is performed using the zoom motor M1 as a drive source.

Next, the internal blocks of the digital camera 1 will be described with reference to the blocks in FIG. First, the internal blocks of the imaging unit 3 will be described. The CCD 303 converts the light image of the subject formed by the zoom lens
The image signal is photoelectrically converted into an image signal of a color component of (red), G (green), and B (blue) (a signal composed of a signal sequence of pixel signals received by each pixel) and output. The timing generator 314
Various timing pulses for controlling the driving of the CCD 303 are generated.

The exposure control in the image pickup section 3 is performed by adjusting the exposure amount of the CCD 303, that is, the charge accumulation time of the CCD 303 corresponding to the shutter speed, since the stop is a fixed stop. If you cannot set an appropriate shutter speed when the subject brightness is low,
By adjusting the level of the image signal output from 303, improper exposure due to insufficient exposure is corrected. That is, when the luminance is low, the exposure control is performed by combining the shutter speed and the gain adjustment. The level adjustment of the image signal is performed in the gain adjustment of the AGC circuit in the signal processing circuit 313.

The timing generator 314 generates a drive control signal for the CCD 303 based on a reference clock transmitted from the timing control circuit 202 of the camera body 2. The timing generator 314 includes, for example, a timing signal of integration start / end (exposure start / end), a readout control signal (horizontal synchronization signal,
A clock signal such as a vertical synchronization signal and a transfer signal is generated and output to the CCD 303.

The signal processing circuit 313 performs predetermined analog signal processing on an image signal (analog signal) output from the CCD 303. The signal processing circuit 313
It has a DS (correlated double sampling) circuit and an AGC (auto gain control) circuit. The CDS circuit reduces the noise of the image signal, and the level of the image signal is adjusted by adjusting the gain of the AGC circuit.

The light control circuit 304 controls the amount of light emitted from the built-in flash 5 during flash photography to a predetermined amount of light set by the overall control unit 211 of the camera body 2. In flash photography, reflected light of flash light from a subject is emitted from the light control sensor 30 at the same time as exposure starts.
5, when the amount of received light reaches a predetermined amount of light emission, the light control circuit 304 outputs a signal from the FL control circuit to stop light emission ST.
P is output.

Next, the internal blocks of the camera body 2 will be described. The A / D converter 205 converts each pixel signal of the image signal into a 10-bit digital signal. The A / D converter 205 includes a timing control circuit 202
Each pixel signal (analog signal) is converted into a 10-bit digital signal based on the A / D conversion clock input from the CPU.

The timing control circuit 202 generates a clock for the A / D converter 205, generates a reference clock, and controls the timing generator 314, as described above. The timing control circuit 202
Controlled by the overall control unit 211.

The black level correction circuit 206 corrects the black level of the A / D converted pixel signal (hereinafter referred to as pixel data) to a reference black level. The WB circuit 207 performs level conversion of pixel data of each of the R, G, and B color components so that the white balance is also adjusted after the γ correction. The WB circuit 207 converts the level of the pixel data of each of the R, G, and B color components using the level conversion table input from the overall control unit 211. The conversion coefficient (gradient of the characteristic) of each color component in the level conversion table is set by the overall control unit 211 for each captured image.

The gamma correction circuit 208 corrects gamma characteristics of pixel data. The γ correction circuit 208 has six types of γ correction tables having different γ characteristics, and performs γ correction of pixel data using a predetermined γ correction table according to a shooting scene and shooting conditions.

The image memory 209 is a memory for storing pixel data output from the gamma correction circuit 208. The image memory 209 has a storage capacity for one frame. That is, in the image memory 209, the CCD 303
In the case of having pixels in rows and m columns, it has a storage capacity for pixel data of n × m pixels, and each pixel data is stored in a corresponding pixel position.

The VRAM 210 is a buffer memory for image data reproduced and displayed on the LCD display unit 10. VR
The AM 210 has a storage capacity for image data corresponding to the number of pixels of the LCD display unit 10.

In the photographing mode, 1
Each pixel data of an image captured every 30 / sec is represented by A /
After being subjected to predetermined signal processing by the D converters 205 to γ correction circuit 208, the signals are stored in the image memory 209, transferred to the VRAM 210 via the overall control unit 211, and displayed on the LCD display unit 10 ( Live view display). Thus, the photographer can visually recognize the subject image from the image displayed on the LCD display unit 10.

In the reproduction mode, the image read from the memory card 8 is subjected to predetermined signal processing by the general control unit 211, transferred to the VRAM 210, and
It is reproduced and displayed on the display unit 10. The LCD display unit 10 includes:
Since the transmissive liquid crystal is used, an image displayed on the LCD display unit 10 can be visually recognized by projecting light from behind the LCD display unit 10 by the backlight 16.
With the backlight 16 turned off, the LCD display unit 1
The image displayed at 0 is almost invisible.

The card I / F 212 is an interface for writing image data to the memory card 8 and reading image data. Also, communication I / F2
Reference numeral 13 denotes an interface conforming to, for example, the USB standard for externally connecting the personal computer 19 so that communication is possible.

The FL control circuit 214 has a built-in flash 5
This is a circuit for controlling the light emission. The FL control circuit 214
The built-in flash 5 based on the control signal of the overall control unit 211
The presence or absence of light emission, the amount and timing of light emission,
The light emission amount of the built-in flash 5 is controlled based on the light emission stop signal STP input from the light control circuit 304 via the overall control unit 211. The RTC 219 is a clock circuit for managing the shooting date and time. It is driven by another power source (not shown).

The operation unit 250 includes the above-described UP switch 6, DOWN switch 7, shutter button 9, FL mode setting switch 11, compression ratio setting switch 12, photographing / playback mode setting switch 14, and quadruple button Z. I have. The shutter button 9 is half-pressed (S1) and depressed (S1) as used in a silver halide camera.
2) is a two-stage switch that can be detected.

When the shutter button is set to the S1 state in the photographing mode, the overall control unit 211 controls the AF motor M2 via the AF motor control circuit 214 so that the contrast of the image data in the image memory 209 is maximized. When the shutter button 9 is released, the focus is locked at that position.

The power switch PS is provided with a self-holding circuit PSH.
When the power switch PS is pressed once in the power-off state, the self-holding circuit PSH maintains the on-state, so that the power supply to the overall control unit 211 and each block is maintained. When the power switch PS is pressed in the power-on state, the power switch PS is detected by the general control unit 211 and the general control unit 2 is pressed.
Numeral 11 immediately turns off the power supply to the blocks that are not necessary for driving the zoom motor M1.
After driving the zoom motor M1 via the zoom motor drive circuit 215 for a predetermined time necessary for the 11 to return to the accommodation position, the block necessary for driving the zoom motor M1 and the power supply to itself are cut off.

Further, the voltage monitoring circuit W of the power supply E is connected to the overall control unit 211, and when the power supply voltage has dropped to 3.7 V, the same processing as the above-described power-off is performed.
Turn off the power of the digital camera. This 3.7V is the minimum voltage required for the front group 3011 of the zoom lens to return to the accommodation position. When the power supply voltage is lower than this, the front group 3011 of the zoom lens can return to the accommodation position. Disappears.

This is based on the premise that immediately after the power supply voltage has dropped to 3.7 V, power is immediately turned off to blocks including the backlight 16 that are not necessary for driving the zoom motor M1. . If the blocks that are not necessary for driving the zoom motor M1 including the backlight 16 are kept energized while the front group 3011 of the zoom lens returns to the accommodation position, the detection level is set to, for example, 4.0V. This has the disadvantage of shortening the useful life of the battery.

The overall control section 211 is composed of a microcomputer, and controls the driving of each member in the image pickup section 3 and the camera body section 2 in an organic manner so as to control the photographing operation of the digital camera 1 overall. is there.

As described above, the imaging unit 3 and the camera body 2 are connected to the mounting surface 334 of the imaging unit 3 by 334a,
A connection terminal group of six groups including 334b, 334c, 334d, 334e, and 334f, and a connection plate 23 of the main body 2
234a, 234b, 234c, 234 provided in
The imaging unit 3 and the main unit 2 are electrically connected by six groups of connection terminals including d, 234e, and 234f.

FIG. 6 shows a detailed internal block of the overall control unit 211, which will be described. Overall control unit 211
Includes a luminance determination unit 211a for setting an exposure control value (shutter speed (SS)) and a shutter speed setting unit 211b. The brightness determination unit 211a determines the brightness of the subject in the shooting mode using an image captured by the CCD 303 every 1/30 (second). That is, the luminance determination unit 211a determines the brightness of the subject using the image data that is renewedly stored in the image memory 209.

The luminance determining section 211a is provided with an image memory 209.
Is divided into nine blocks, and the luminance data representing each block is calculated using the pixel data of the G (green) color component included in each block.

The shutter speed setting section 211b sets the shutter speed (integration time of the CCD 303) based on the result of the brightness determination of the subject by the brightness determination section 211a. Shutter speed setting section 211b
Has a table of shutter speed SS.

The shutter speed SS is initially set to 1/128 (second) when the camera is started. In the photographing mode, the shutter speed setting unit 211b sets the brightness judgment unit 2
According to the determination result of the brightness of the subject by 11a, the initial value is changed and set one step at a time to the high speed side or the low speed side.

The overall control unit 211 sets a proper shutter speed SS, γ correction, and filtering correction (described later) according to the shooting scene. "Medium brightness backlight scene"
And a scene determination unit 211c that determines four types of shooting scenes of “high brightness scene”. "Low brightness scene"
Is a scene that normally requires auxiliary light from a flash, such as indoor shooting or nighttime shooting. A “medium-luminance normal scene” is a mode in which illumination light (including natural light and artificial light) for the main subject is in direct light. In addition, the scene can be photographed without auxiliary light because its brightness is appropriate. The “medium brightness backlight scene” is a scene in which the overall brightness is appropriate, but the flash light is preferable because the illumination light for the main subject is backlight, and the “high brightness scene” is, for example, a clear sea scene. It is a very bright scene as a whole, like shooting at a ski resort.

Further, the overall control unit 211 determines whether the captured image is a normal photographed image of a landscape, a person, or the like (hereinafter, this type of captured image is referred to as a natural image), a character drawn on a board, (Hereinafter, an image similar to a binary image of this type is referred to as a character image).
11e.

The image determining unit 211e is provided with an image memory 209
A histogram of the luminance data at each pixel position is created based on the pixel data constituting the captured image stored in the storage device, and the content of the captured image is determined based on the histogram. In general, a histogram of luminance data of a captured image is a so-called one-peak distribution having a single peak value with a small bias in the luminance distribution in the case of a natural image. In the case of a character image, a bias in the luminance distribution is observed in each of a white background portion and a black character portion.
Mountain distribution. Therefore, the image determination unit 211e determines whether the histogram of the luminance data of the captured image has a single peak distribution,
It is determined whether the captured image is a natural image or a character image by determining whether the image is a mountain distribution. Then, this determination result is also stored in the memory 211d.

The overall control unit 211 includes a filter unit 211f for performing a filtering process and a recorded image generating unit 211g for generating a thumbnail image and a compressed image in order to perform the recording process of the photographed image. In order to reproduce the displayed image on the LCD display unit 10,
A reproduction image generation unit 211h that generates a reproduction image is provided.

The filter section 211f corrects the high-frequency component of the image to be recorded by a digital filter to correct the image quality related to the outline. Filter section 211
f is a digital filter for performing standard contour correction for each of the compression ratios K = 1/8 and 1/20, and two types of digital filters for enhancing the contour and the contour for the standard contour correction. A total of five types of digital filters, two types of digital filters to be weakened, are provided.

The recording image generation unit 211g is provided in the image memory 2
The pixel data is read from 09 and a thumbnail image and a compressed image to be recorded on the memory card 8 are generated. The recording image generation unit 211g reads pixel data for every eight pixels in both the horizontal direction and the vertical direction while scanning from the image memory 209 in the raster scanning direction, and sequentially transfers the pixel data to the memory card 8, thereby obtaining the thumbnail image. Is recorded on the memory card 8 while generating.

The recording image generation unit 211g reads out all pixel data from the image memory 209 and converts these pixel data into JPE data such as two-dimensional DCT transform and Huffman coding.
A predetermined compression process according to the G method is performed to generate image data of a compressed image, and the compressed image data is recorded in the main image area of the memory card 8.

In the photographing mode, when photographing is instructed by the shutter button 9 in the photographing mode, the overall control section 211 displays the thumbnail image of the image taken into the image memory 209 after the photographing instruction and the compression ratio set by the compression ratio setting switch 12. A compressed image compressed by the JPEG method using K is generated, and tag information (frame number, exposure value,
Both images are stored in the memory card 8 together with information such as shutter speed, compression ratio K, shooting date, flash on / off data at the time of shooting, scene information, image determination result, and the like.

FIG. 7 schematically shows a data array in the memory card 8. Images recorded by the digital camera can store 40 frames of images at a compression ratio of 1/20, and each frame includes a tag 81 and high-resolution image data ((640 × 480) compressed in JPEG format. ) Pixel) 8
2 and image data ((80 × 60) pixels) 83 for thumbnail display are recorded. For each frame, for example, E
It can be handled as an image file in the XIF format.

When the photographing / reproduction mode setting switch 14 is set to the reproduction mode, the image data having the largest frame number in the memory card 8 is read out, and the data is expanded by the reproduction image generation section 211h.
By being transferred to 0, the display unit 10 displays the image with the largest frame number, that is, the image that has been taken up close. By operating the UP switch 6, an image with a large frame number is displayed, and by pressing the DOWN switch 7, an image with a small frame number is displayed.

The sequence at the time of power on / off in this embodiment will be described in detail with reference to the time chart of FIG. Although the processing in the shooting mode is described here, the same applies to modes other than the shooting mode.

When the power button is pressed at time T0 when the digital camera is in the power-off state, the general control unit 211 constituted by the CPU is immediately activated, and the digital camera is turned on. Further, with the power button on as a trigger, the overall control unit 211 instructs to start driving the zoom motor M1, and the front group 3011 of the zoom lens 301 moves from the storage position to a predetermined position (wide end). This movement is completed within 3 seconds.

Further, the overall control unit 211 operates from time T0 to t.
One second later, the power supply is instructed to the video circuit. The video circuit here is the VRAM 210 and the LCD 10 in FIG.
FIG. 8 shows the on / off state of the LCD and the signal waveform inside the LCD display unit as a Video signal. Since the LCD driving IC inside the LCD display unit 10 is not stable during the period t2 (about 0.3 seconds), as shown in FIG.
The waveform of the o signal is distorted. At this time, when the backlight 16 is turned on to make the image displayed on the LCD visible, noise is displayed and the image becomes hard to see. Therefore, by setting the timing at which the backlight 16 is turned on after t2 when the LCD display unit is stabilized, noise becomes less noticeable. That is, during the period of t2, the image displayed on the LCD display unit is not observed by the observer.

The above situation can be applied to other blocks that handle image signals, to a lesser extent. For example, since the WB circuit 207 is not stable for a predetermined time after energization, if the backlight 16 is turned on at the same time after energization of the WB circuit 207, a state in which noise caused by the instability of the WB circuit 207 becomes visible. .

Next, the processing when the power is turned off will be described. Even when the power button is pressed at time T1 when the digital camera is in the power-on state, the entire control unit 211 maintains the power-on state for a time t3 (about 3 seconds) necessary for the zoom motor M1 to return to the storage position. After the lapse of time t3, the digital camera is turned off. During the period of time t3, all the blocks that are not necessary for driving the zoom motor M1 are turned off, so that the LCD display unit 10 and the backlight 16 are also turned off, and no video signal is output.

As a result, the lens can be returned to the housing position even when the battery level is low. If a block with large power consumption (for example, the backlight 16) is energized, the zoom motor M
Driving 1 may further reduce the battery level and make it impossible to return the lens to the storage position.

In the present embodiment, when it is detected from the monitoring result of the voltage monitoring circuit W that the power supply voltage has dropped to 3.7 V or less, the same sequence as when the power off instruction is given in FIG. Blocks that are not necessary for driving the zoom motor M1 are all de-energized, and then the zoom motor M1 is turned off.
In this sequence, the power is completely turned off after the photographing lens is moved to the accommodation position by driving the camera 1. It should be noted that the power consumption can be reduced by only partially turning off the energization of the blocks, for example, only the energization of the backlight, without shutting off the energization of all the blocks that are not necessary for driving the zoom motor M1. Is also good. In addition, the following control method is also possible.

FIG. 9 shows a time chart in this control method. The processing at power-on is the same as in FIG. When it is detected at time T2 that the power supply voltage has dropped to 3.7 V or less, the power supply to the LCD 10 is cut off, the transmission of the Video signal is stopped, and the backlight 16 is turned on and off to display a warning. Cut off the current. Then, the energization of all the blocks not necessary for driving the zoom motor M1 is cut off. At this stage, the photographing lens has not been moved to the accommodation position, but there is a margin for power supply power. Thereafter, when the power button is pressed by the user at time T3,
The taking lens is moved to the storage position.

[0075]

According to the present invention, in a retractable digital camera, the photographing lens is not housed in the housing position even when the power is turned off due to lack of power supply power, and the photographing lens may be damaged. Can be prevented, and the portability when the power is turned off due to battery exhaustion is improved.

[Brief description of the drawings]

FIG. 1 is an external view of a digital camera according to an embodiment as viewed from the front.

FIG. 2 is an external view of the digital camera according to the embodiment as viewed from the back.

FIG. 3 is an external view of the digital camera according to the embodiment as viewed from the bottom.

FIG. 4 is a diagram showing a schematic configuration inside the image pickup unit when the photographing lens (a) is housed and when (b) moves to a predetermined position.

FIG. 5 is an internal block diagram of the digital camera according to the embodiment.

FIG. 6 is a detailed block diagram of an overall control unit.

FIG. 7 is a diagram schematically showing a data array in a memory card.

FIG. 8 is a time chart showing a sequence when the power is turned on and off according to the embodiment.

FIG. 9 is a time chart showing a different sequence of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Digital camera 2 Camera main body 3 Imaging part 8 Memory card 9 Shutter button 10 LCD display part 16 Backlight 209 Image memory 211 Overall control part 250 Operation part 301 Photographing lens 303 CCDZ Quadruple button W Voltage monitoring circuit M1 Zoom motor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H054 AA01 2H100 DD02 FF01 2H101 BB08 5C022 AA11 AB67 AC16 AC18 AC42 AC54 AC69 AC73 AC74

Claims (4)

[Claims] 1. An object image is formed on an image sensor by a photographing lens, and the image of the object is converted into an electric signal by the image sensor. In a digital camera having a photographing lens at a position where focusing is possible, monitoring means for monitoring a power supply voltage, and a power supply voltage is necessary for moving the photographing lens to the accommodation position based on a monitoring result of the monitoring means. Control means for moving the photographing lens to the housing position before the minimum voltage is reached. 2. An object image is formed on an image sensor by a photographing lens, and the image of the object is converted into an electric signal by the image sensor. In a digital camera including a photographing lens at a position where focusing is possible, and a display unit that displays a photographed image based on the electric signal, a monitoring unit that monitors a power supply voltage, based on a monitoring result of the monitoring unit, A digital camera, comprising: a control unit configured to issue a warning before a power supply voltage becomes a minimum voltage necessary for moving the photographing lens to the housing position. 3. The warning according to claim 2, wherein the warning is displayed by the display unit, and the control unit cuts off the power supply to the display unit after the warning is displayed. Digital camera. 4. The apparatus according to claim 1, wherein the control means moves the photographing lens to the storage position when a power-off is instructed by a user operating an operation unit after the warning. The digital camera according to 2 or 3.