JP2001275036A - Electronic camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic camera which can suppress deterioration in picture quality caused when image information is converted from analog to digital without causing the analog/digital conversion speed of the image information to decrease. SOLUTION: This digital camera is equipped with three signal processing parts 61 each equipped with a CDS circuit 61a and an A/D converter 61b, and an arithmetic circuit 62. Each CDS circuit 61a outputs analog image signals of respective pixels from a CCD 303 after performing specific noise reduction processing. Each A/D converter 61b converts the given analog image signals of the respective pixels into digital image signals and outputs them. The arithmetic circuit 62 adds the given digital image signals of the respective pixels, averages the obtained addition values by dividing it by how many times the signal processing parts 61 operate, and outputs the result as a digital image signal to an image processing part 200.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic camera (including a digital camera and a digital video camera) which obtains digital image information by performing analog / digital conversion of analog image information output from an imaging means. It is.

[0002]

2. Description of the Related Art In an electronic camera of this type, image quality degradation occurs when analog / digital (hereinafter, referred to as A / D) conversion means converts analog image information output from an imaging means to analog / digital conversion. How to control the emission has been an issue.

In the prior art, the resolution of the A / D conversion is improved by increasing the number of bits of the A / D conversion means, thereby improving the accuracy of the A / D conversion.
There is one that suppresses deterioration of image quality during D conversion.

[0004]

However, when the number of bits of the A / D conversion means is increased as in the above-mentioned prior art, the amount of signal processing in the A / D conversion means is increased. There is a problem that the / D conversion speed is reduced.

[0005] In addition, the influence of noise at the time of A / D conversion is also a major factor in the deterioration of image quality at the time of A / D conversion. Because measures against noise are not taken properly,
There is also a problem that deterioration of image quality due to the influence of noise at the time of A / D conversion cannot be prevented.

In view of the foregoing, the present invention has been made in view of the above circumstances, and it is possible to suppress degradation in image quality that occurs when image information is converted from analog to digital without causing a reduction in the analog / digital conversion speed of image information. The purpose is to provide a camera.

[0007]

A technical means for achieving the above object is an electronic camera which obtains digital image information by converting analog image information output from an imaging means from analog to digital. The imaging means; a plurality of analog / digital conversion means for individually performing analog / digital conversion of the analog image information output from the imaging means; Calculating means for adding the digital values obtained and outputting the digital values as the image information in digital form.

Preferably, the electronic camera has a battery remaining amount detecting means for detecting a remaining amount of a battery mounted as a power supply in the electronic camera, and the battery remaining amount indicated by the detection result of the electronic remaining amount detecting means. First control means for determining the number of operating analog / digital conversion means to be operated among the plurality of analog / digital conversion means,
It is better to further comprise

Preferably, the electronic camera receives a first switching input for switching an operation mode of the electronic camera between a normal mode and a power saving mode in which power consumption is suppressed. And a function of switching the operation mode between the normal mode and the power saving mode in accordance with the first switching input input via the first input means, wherein the operation mode is the power saving mode. When the electronic camera is in the power mode, a second number of the analog / digital converters, which is smaller than the number of the analog / digital converters provided in the electronic camera, is operated.
And a control means.

Further, preferably, the electronic camera comprises:
Display means for displaying the image information in digital format during shooting standby; recording means for image storage for recording the image information in digital form; shooting instruction means for instructing shooting for recording; and the display means When the photographing is repeatedly performed at a predetermined interval to display the image information, a smaller number of the analog / digital conversion units are operated as compared with the case where the photographing is performed according to the instruction of the photographing instruction unit. And control means.

Preferably, the arithmetic means adds the respective digital values output from the respective analog / digital conversion means, and adds the added value to the analog / digital signal during operation.
It is preferable to divide by the number of operations of the digital conversion means and output the digital image information.

Further, preferably, the electronic camera comprises:
It should be a digital camera.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS <General Description> FIGS. 1 to 4 are a front view, a rear view, a side view and a bottom view of a digital camera 1 according to an embodiment of the present invention, and FIG. FIG. 2 is a block diagram showing an internal configuration of No. 1.

The digital camera 1 is, as shown in FIG.
It comprises a box-shaped camera body 2 and a rectangular parallelepiped imaging unit 3 (shown in bold lines in FIGS. 1, 2 and 4). The imaging unit 3 includes a zoom lens 301 with a macro function, which is a photographing lens, and, similarly to a silver halide lens shutter camera, a light control sensor 305 that receives reflected light of flash light from a subject, and measures a distance to the subject. A distance measuring sensor 306 and an optical finder 31 are provided.

A zoom lens 30 is provided inside the image pickup section 3.
A CCD which is a CCD color area sensor at a position behind 1
(Imaging means) 303 (see FIG. 5)
Is a part of the imaging circuit 302.

As shown in FIG. 1, on the front surface of the camera body 2, a grip portion 4 is provided at the left end and a built-in flash 5 is provided at the upper center, and a shutter button (photographing instruction means) 8 is provided on the upper surface. ing.

On the other hand, as shown in FIG.
An LCD (display means) 10 for displaying a captured image on a monitor (corresponding to a viewfinder), reproducing and displaying a recorded image, and the like is provided substantially in the center of the rear surface of the LCD. Also, LC
Below D10, a group of key switches 221 to 226 for operating the digital camera 1 and a power switch 227 are provided. On the left side of the power switch 227, an LED 228 that lights up when the power is on and an LED 2 that indicates that the memory card (recording unit) 91 is being accessed are displayed.
29 are arranged.

Further, on the back of the camera body 2, a mode setting switch 1 for switching a mode among "shooting mode", "reproduction mode" and "preference mode" is provided.
4 are provided (see FIG. 3).

The photographing mode is a mode for photographing. The playback mode is a mode in which a captured image recorded on the memory card 91 is played back and displayed on the LCD 10, and the preference mode is a mode in which various settings are made by selecting from displayed selection items. is there. With the preference mode, the operation mode of the digital camera 1 can be switched between a normal mode and a power saving mode in which power consumption is suppressed, as described later. The normal mode and the power saving mode will be described later in detail.

The mode setting switch 14 is a three-contact slide switch. In FIG. 2, when the switch is set downward, the photographing mode is set. When the switch is set in the center, the reproduction mode is set. When the switch is set upward, the preference mode is set. .

A four-position switch 230 is provided on the right side of the rear of the camera. Zooming is performed by pressing buttons 231 and 232, and exposure correction is performed by pressing buttons 233 and 234.

As shown in FIG. 2, on the back of the image pickup unit 3,
LCD button 32 for turning on / off LCD 10
1 and a macro button 322 are provided. When the LCD button is pressed, on / off of the LCD display is switched.
For example, when photographing is performed exclusively using the optical viewfinder 31, the LCD display is turned off for the purpose of saving power. At the time of macro shooting, when the macro button 322 is pressed, the AF motor 308 (see FIG. 5) is driven, and the zoom lens 301 is ready for macro shooting.

As shown in FIG. 3, a DC input terminal 235 is provided on a side surface of the camera body 2.

As shown in FIG. 4, a battery loading chamber 18 and a card loading chamber 17 are provided on the bottom of the camera body 2. The card loading chamber 17 has two card slots 17a for loading a memory card 91 and a function card 92,
17b. Both loading chambers can be opened and closed by a clamshell type lid 15.

In the digital camera 1, four AA batteries are loaded into the battery loading chamber 18, and a power source battery (battery) 236 (see FIG. 5) formed by connecting them in series is used as a driving source. Of course, it is also possible to supply the power from the adapter from the DC input terminal 235 shown in FIG. 4 and use it.

Next, the internal configuration of the imaging section 3 will be described in order with reference to FIG.

An image pickup circuit 302 converts an optical image of a subject formed on the CCD 303 by the zoom lens 301 into a CCD image.
R (red), G (green), B
(Blue) color component analog image signal (image information)
Output as

In the digital camera 1, the exposure control in the image pickup section 3 is performed not only by adjusting the aperture but also by the CCD 303.
(The charge accumulation time of the CCD 303 corresponding to the shutter speed) is also adjusted. If you cannot set an appropriate shutter speed when the subject brightness is low,
By adjusting the level of the image signal output from the CCD 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 by the AGC in the signal processing circuit 313 described later.
(Auto gain control) circuit.

The timing generator 314 generates a drive control signal for the CCD 303 based on a clock transmitted from the timing control circuit 202 in the camera body 2. The timing generator 314 generates clock signals such as, for example, integration start / end (ie, exposure start / end) timing signals and readout control signals (horizontal synchronization signal, vertical synchronization signal, and transfer signal) of the light receiving signal of each pixel. Then, the signal is output to the CCD 303 and the signal processing circuit 313.

The signal processing circuit 313 is a portion in which the features of the present invention are most reflected, and its detailed configuration will be described in detail later. As a rough function, the signal processing circuit 313 has built-in image signal noise supplied from the CCD 303. After being reduced by a CDS (correlated double sampling) circuit 61a (see FIG. 7), the image signal is A / D converted by a plurality of A / D converters (A / D conversion means) 61b and output.

The dimming circuit 304 controls the light emission amount of the built-in flash 5 in flash photography to a predetermined light emission amount set by the overall control unit (first to third control means) 211 of the camera body 2. It is. In the flash photography, the reflected light of the flash light from the subject is received by the light control sensor 305 at the same time as the start of exposure, and when the amount of received light reaches a predetermined light emission amount, the light control circuit 304 sends the reflected light through the overall control unit 211. An emission stop signal is output to the flash control circuit 214 of the camera body 2. The flash control circuit 214 forcibly stops the light emission of the built-in flash 5 in response to the light emission stop signal, whereby the light emission amount of the built-in flash 5 is controlled to a predetermined light emission amount.

Further, inside the image pickup section 3, a zoom motor 307 for changing the zoom ratio of the zoom lens 301 and moving the lens between the accommodation position and the photographing position, and an AF (for focusing) are provided. An auto focus) motor 308 and an aperture actuator 309 for adjusting the aperture are provided.

Next, the internal structure of the camera body 2 will be described.

The overall control unit 211 mainly comprises a CPU.
The driving of each of the peripheral components in the image pickup section 3 and the camera body section 2 is organically controlled, and the photographing operation of the digital camera 1 is totally controlled. The peripheral configuration is connected by an address bus, a data bus, a control bus, and the like.

Although the flow of image data in FIG. 5 (and FIG. 6 to be described later) is also indicated by arrows between peripheral components for convenience, the image data is actually transmitted to the Sent for each peripheral configuration. Therefore, a work RAM composed of a DRAM is provided in the overall control unit 211.
211a and a flash ROM 211b for storing programs are built-in.

Next, a configuration relating to processing of an image signal and image display inside the camera body 2 will be described.

The digital image signal sent from the signal processing circuit 313 of the image pickup unit 3 is subjected to various image processing in an image processing unit 200 in the camera body 2. FIG. 6 is a block diagram illustrating a configuration of the image processing unit 200.

The black level correction circuit 206 corrects the black level of the digital image signal (hereinafter referred to as "pixel data") sent from the signal processing circuit 313 to a reference black level. Also, the WB circuit 207
It performs level conversion of pixel data of each color component of R, G, and B, and adjusts white balance in consideration of γ correction in a later process. The white balance is adjusted using a level conversion table (correctly, the data) input to the WB circuit from the overall control unit 211, and the conversion coefficient (gradient of the characteristic) of each color component of the level conversion table is controlled by the overall control. The setting is performed by the unit 211 for each captured image.

The gamma correction circuit 208 corrects gamma characteristics of pixel data. The output from the gamma correction circuit 208 is sent to the image memory 209 as shown in FIGS.

The image memory 209 is a memory for storing pixel data output from the image processing section 200 and has a storage capacity for one frame. That is, when the CCD 303 has pixels arranged in a matrix of n rows and m columns (n and m are natural numbers),
It has a storage capacity for pixel data of n × m pixels, and each pixel data is stored in a corresponding storage area (address).

The VRAM 210 is a buffer memory for image data reproduced and displayed on the LCD 10. VRAM2
Reference numeral 10 has a storage capacity of image data corresponding to the number of pixels of the LCD 10.

With such a configuration, in a state where the mode setting switch 14 is set to the photographing mode (a photographing standby state), each pixel data of an image photographed at predetermined intervals by the image pickup unit 3 is subjected to signal processing. After being subjected to predetermined signal processing by the circuit 313, the signal is processed by the image processing unit 200, stored in the image memory 209, transferred to the VRAM 210 via the overall control unit 211,
10 (live view display). This allows
In the photographing standby state, the photographer can visually recognize the subject image from the image displayed on the LCD 10.

In the reproduction mode, the image read from the memory card 91 is subjected to predetermined signal processing by the general control unit 211, and then transferred to the VRAM 210 to be reproduced and displayed on the LCD 10. When an image is displayed on the LCD 10, the backlight 16 is turned on under the control of the overall control unit 211.

Next, other components in the camera body 2 will be described in order.

The timing control circuit 202 generates a clock for the timing generator 314 under the control of the general control unit 211.

The card I / F 212 is a card slot 1
This is an interface for exchanging signals with various cards loaded in 7a and 17b. Specifically, it writes and reads image data from and to the memory card 91, and inputs and outputs image data and various signals to and from the various function cards 92. As described above, the digital camera 1 has two card slots, and can accommodate two cards.

The flash control circuit 214 is a circuit for controlling the light emission of the built-in flash 5 as described above. The flash control circuit 214 controls the presence / absence of light emission of the built-in flash 5, the amount of light emission, the light emission timing, and the like based on the control signal of the overall control unit 211, and controls the built-in flash 5 based on the light emission stop signal input from the dimming circuit 304. Controls the amount of light emission.

The clock circuit 219 is a clock circuit for managing the shooting date and time. It is driven by another power source (not shown).

A zoom motor driving circuit 215 and an AF motor driving circuit 216 for driving the zoom motor 307 and the AF motor 308 are provided in the camera body 2.
Is provided. These circuits include a shutter button 8 and other various switches and buttons described above, and an operation unit 25 which is a button.
Functions according to the operation of 0.

For example, the shutter button 8 is a two-stage switch capable of detecting a half-pressed state and a depressed state as employed in a silver halide camera. Then, the distance measuring sensor 30
The distance information is obtained from the overall control unit 211 according to the distance measurement information from
Is entered. Then, in accordance with an instruction from the overall control unit 211, the AF motor drive circuit 216 drives the AF motor 308 to move the zoom lens 301 to a focus position.

When the buttons 231 and 232 are pressed, signals from these buttons are sent to the general control unit 211, and the zoom motor driving circuit 215 drives the zoom motor 307 to instruct the zoom motor 307 according to an instruction from the general control unit 211. Move the lens and zoom.

In addition, an aperture drive circuit 217 for driving the aperture actuator 309 is also provided in the camera body 2.

The power supply to the overall control unit 211 and each peripheral configuration is performed by a power supply circuit 237.
Is supplied with power from an AC adapter via a DC input terminal 235 or from a power supply battery 236. The power supply circuit 237 includes a voltage detection circuit (a battery remaining amount detection unit) 23.
8 is connected so that a voltage between terminals (a voltage drop in each configuration) of each configuration when power is supplied to each configuration in the digital camera 1 can be detected. The detected voltage is input to the overall control unit 211, and based on the input voltage value, the overall control unit 211 supplies power to each unit of the digital camera 1 via the power supply circuit 237 (here, the power supply state). Then, the power supply battery 236 is recognized.

Although the components in the camera body 2 have been described above, the overall control unit 211 performs various functions by software in addition to data transfer and timing control with peripheral components.

For example, the overall control unit 211 has a brightness determination function for setting an exposure control value (shutter speed and aperture value) and an exposure setting function. The brightness determination function is performed by the CCD 303 for live view display in a shooting standby state every 1/30 (second).
The brightness of the subject is determined using the image stored in the image memory 209. The exposure setting function sets the shutter speed (integration time of the CCD 303) and the aperture value based on the result of the determination of the brightness of the subject by the luminance determination.

The overall control unit 211 has a filtering function, a recorded image generating function, and a reproduced image generating function in order to perform a recording process of a captured image.

The filtering function corrects the high-frequency component of the image to be recorded by a digital filter to correct the image quality related to the outline.

The recording image generation function reads out pixel data from the image memory 209 and generates a thumbnail image and a compressed image to be recorded on the memory card 91. Specifically, while scanning in the raster scanning direction from the image memory 209, pixel data is read out every eight pixels in both the horizontal direction and the vertical direction, and sequentially transferred to the memory card 91 to generate a thumbnail image. Memory card 91
To record. Further, when recording the compressed image data on the memory card 91, all the pixel data is read out from the image memory 209, and these pixel data are subjected to a predetermined compression process according to the JPEG system such as two-dimensional DCT conversion, Huffman coding, etc. Record at 91.

For example, the memory card 91 has 1600 ×
Compressed image data of 1200 pixels, image data for thumbnail display of 80 × 60 pixels, and tab information relating to the captured image are recorded. In this case, the capacity of image data for one frame is about 1 MB. When an audio card is mounted as the function card 92, audio data can also be recorded, and link information to the audio file is written in the tag of the image file in the memory card 91.

The reproduction image generation function is provided in the memory card 9.
This is a function for expanding the data of the compressed image recorded in No. 1 to generate a reproduced image. As a specific operation, when the mode setting switch 14 is set to the reproduction mode, the memory card 9
The image data having the largest frame number in 1 is read out, expanded, and transferred to the VRAM 210. As a result, the image with the largest frame number, that is, the most recently captured image is displayed on the LCD 10.

Further, the overall control unit 211 includes key switch groups 211 to 226 (or buttons 231 to 234).
The digital camera 1 further has a function of responding to a switching input (first switching input) for switching an operation mode input via the PC, and switching the operation mode of the digital camera 1 between a normal mode and a power saving mode. . As a specific operation, the mode setting switch 14 is set to the preference mode, and the key switch groups 221 to 226 (or the buttons 231 to 234) are operated to call the operation mode setting mode, and as shown in FIG. By setting the operation mode to the normal mode or the power saving mode in accordance with the guidance of the display contents of the LCD 10, the operation mode can be set.

For example, when the operation mode setting screen 51 of FIG. 7 is displayed on the LCD 10, the user operates the button 233 or 234 to move the cursor 52 to the first display position 51a corresponding to the normal mode and the power saving. The operation mode is set by operating the button 232 or the like in a state where the operation mode has been moved to any one of the second display positions 51b corresponding to the mode.

Here, the difference between the normal mode and the power saving mode will be described.
In the normal mode, the LCD 10 is turned on and the provisionally shot image is displayed on the LCD 10 when the shooting mode is set to the shooting mode 4, but the LCD 10 is turned off in the power saving mode. In this case, photographing is performed using the optical finder 31.

In the power saving mode, the overall control unit 211
The clock frequency at which the CPU is driven is set lower than in the normal mode. Further, the digital camera 1 is provided with an auto power-off function in which the power is automatically turned off when an operation input is not continuously performed for a certain period of time in order to save power consumption. , In power saving mode than in normal mode,
The time from when the operation input is not performed until the power is turned off is set to be short.

FIG. 8 is a block diagram showing a configuration of the signal processing circuit 313. The signal processing circuit 313 includes a plurality of (here, three) signal processing units 6.
1 and an arithmetic circuit (arithmetic means) 62. Each signal processing unit 61 includes a CDS circuit 61a and an A / D converter 61.
b. In this embodiment, the CCD 30
The analog-format image signal output from 3 is input to each signal processing unit 61.

The CDS circuit 61a of each signal processing unit 61
According to a reference clock provided from the timing generator 314, the analog image signal of each pixel sequentially provided from the CCD 303 is subjected to a predetermined noise reduction process, and then output to the A / D converter 61b.

A / D converter 61b of each signal processing unit 61
Converts the analog image signal of each pixel sequentially supplied from the CDS circuit 61a into a digital image signal according to the reference clock supplied from the timing generator 314, and outputs the digital image signal to the arithmetic circuit 62.

The signal processing section 61 is individually turned on and off by the overall control section 211. In the on state, when an image signal is input to the signal processing unit 61, noise reduction processing and A / D conversion processing are performed. In the off state, the noise reduction processing operation and A / D conversion of the signal processing unit 61 are performed. The D conversion processing operation is stopped.

The arithmetic circuit 62 adds the digital image signals of the respective pixels sequentially output from the respective signal processing units 61, and operates the signal processing unit 61 provided from the overall control unit 211.
, The sum of the digital image signals of each pixel obtained by the addition is divided by the number of operations of the signal processing unit 61, averaged, and output to the image processing unit 200 as a digital image signal. I do.

In this embodiment, the number of operations of the signal processing unit 61 is controlled by the general control unit 211. The details of the control will be described later with reference to the flowchart of FIG. 9. However, roughly speaking, the number of operations is determined based on the following three setting factors.

The first setting factor is the remaining battery power of the power supply battery 236. The overall control unit 211 includes a voltage detection circuit 238
The remaining battery level of the power supply battery 236 is periodically monitored based on the voltage value output from the CPU, and the number of operating signal processing units 61 to be operated is determined based on the detected remaining battery level. . In this case, as the remaining battery power decreases, the number of operating signal processing units 61 increases from three to two.
The number is gradually reduced from two to one.

For example, when the output voltage of power supply battery 236 is 6 volts when the amount of charge stored in power supply battery 236 is full, and when the output voltage is 5 volts to 6 volts, three The signal processing unit 61 is operated. When the voltage is between 4.5 volts and 5 volts, two signal processing units 61 are operated, and when the voltage is 4.5 volts or less, one signal processing unit 61 is operated.

The second setting factor is that the digital camera 1
Is the setting state of the operation mode. The overall control unit 211
When the operation mode is set to the normal mode, the operation number of the signal processing units 61 corresponding to the remaining amount of the power supply battery 236 is operated in principle, while when the operation mode is set to the power saving mode, 1 Signal processing units 61
To work.

The third setting factor is that the digital camera 1
Is in the shooting standby state. The general control unit 211 operates one signal processing unit 61 in a state where shooting for live view display is being performed, and while performing shooting for recording in accordance with an instruction from the shutter button 8. Operates the number of signal processing units 61 corresponding to the remaining amount of the power supply battery 236 in principle.

FIG. 9 is a flowchart (subroutine) showing the operation number determination processing of the signal processing section 61 by the overall control section 211. In step S1, it is determined whether the operation mode is set to the power saving mode. If the operation mode is set to the power saving mode, step S2 is performed.
On the other hand, when the operation mode is set to the normal mode, the process proceeds to step S3.

In step S2, the number of operations of the signal processing section 61 is set to one. In this setting state, the CCD3
The image signal of each pixel output from the signal processing unit 03 is subjected to noise reduction processing and A / D conversion processing by one signal processing unit 61 of the signal processing circuit 313, and is sent to the image processing unit 200 via the arithmetic circuit 62. Can be

In step S3, it is determined whether or not the shutter button 8 is half-pressed (whether or not shooting for recording has been instructed). If Yes, the process proceeds to step S4.
If No, the process proceeds to step S2.

In step S4, the operation number of the signal processing unit 61 is set to a number corresponding to the remaining battery level, and photographing for recording is performed. In this setting state, the image signal of each pixel output from the CCD 303 is subjected to noise reduction processing and A / D conversion processing by the signal processing units 61 of the number of operations corresponding to the remaining battery level of the signal processing circuit 313, and the operation is performed. The digital image signal output from each signal processing unit 61 in the
The signals are added by the arithmetic circuit 62, divided by the number of operations of the signal processing unit 61, averaged, and sent to the image processing unit 200.

Note that steps S1 to S
The process of step S1 is executed in a state where the mode setting switch 14 is set to the photographing mode.
In addition, the number of operations of the signal processing unit 61 is controlled by repeatedly executing the processing of step S4 at a high speed. The signal processing circuit 313 is operated in a state where the mode setting switch 14 is set to the photographing mode, and is stopped in other states.

As described above, the signal processing circuit 313 is provided with a plurality of A / D converters 61b, and the image signals A / D converted by each of the A / D converters 61b are added by the adding circuit 62. The image signal is added, divided by the number of operations of the A / D converter 61b, averaged, and output to the image processing unit 200 as a digital image signal. A / D
At the time of conversion, the random noise that is randomly generated independently between the A / D converters 61b is 1 / √m (where
m indicates the number of operations of the A / D converter 61b). As a result, since the number of bits of the A / D converter 61b is not increased unlike the related art, the deterioration of the image quality that occurs at the time of A / D conversion can be achieved without lowering the A / D conversion speed of the image signal. And the image quality can be improved.

Each signal processing section 61 provided with the A / D converter 61b is provided with a CDS circuit 61b for performing noise reduction processing of an analog image signal. When processing is performed, random noise generated independently and randomly between the CDS circuits 61a is 1 / √m (where m is the CDS circuit 61a).
(a) indicates the number of operations), thereby further improving the image quality.

Further, when the remaining battery level of the power supply battery 236 is low, the signal processing unit 6 according to the remaining battery level.
1 (A / D converter 61b) is reduced in number, so that the amount of power stored in the power supply battery 236 can be used efficiently, and as a result, the power supply battery 23
6 has an effect of increasing the possible photographing time (or the number of times of photographing) until the charged amount becomes zero.

When the operation mode of the digital camera 1 is the power saving mode, the signal processing unit 61 (A / A
Since the operation number of the D converter 61b) is reduced to one, the power consumed by the signal processing unit 61 in the power saving mode can be effectively suppressed,
The power consumption of the electronic camera can be effectively suppressed.

Further, when the digital camera 1 is taking a picture for live view display, it is not always necessary to obtain a high-quality image, so that one signal processing unit 61 (A / D converter 61b) ) Is operated to suppress the power consumed by the signal processing unit 61, so that the power consumption used at the time of live view display can be suppressed.

The arithmetic circuit 62 is connected to each signal processing unit 61
Are added, and the added value is divided by the number of operating signal processing units 61 in operation, averaged, and output as a digital image signal. By adding the respective digital values output from 61, it is possible to prevent the number of bits of the output terminal of the arithmetic circuit 62 that outputs the digital image signal from increasing and to prevent the configuration of the arithmetic means from becoming complicated.

In the present embodiment, the case where the present invention is applied to the digital camera 1 has been described. However, the present invention may be applied to a digital video camera.

[0087]

According to the present invention, a plurality of analog / digital conversion means are provided,
Analog / digital conversion means
The digitally converted image information is added by the adding means and output as digital image information. Therefore, when the image information is converted from analog to digital by each analog / digital converting means, The random noise generated independently and randomly between the digital / digital conversion means can be reduced to 1 / （n (where n indicates the number of analog / digital conversion means). As a result, since the number of bits of the analog / digital conversion means is not increased unlike the prior art, the analog / digital conversion speed of image information is not reduced.
It is possible to effectively suppress the deterioration of the image quality that occurs at the time of analog / digital conversion, and to improve the image quality.

According to the second aspect of the present invention, the number of operating analog / digital conversion means is determined according to the remaining battery power of the battery mounted on the electronic camera. The remaining power storage amount can be used efficiently, and as a result, effects such as an increase in the photographable time (or the number of times of photographing) until the power storage amount of the battery becomes zero can be obtained.

According to the third aspect of the present invention, when the operation mode is the power saving mode in which the power consumption is suppressed, the number of analog / digital conversion units smaller than the number of analog / digital conversion units provided in the electronic camera is reduced. Since the digital / digital converter is operated, the power consumed by the analog / digital converter in the power saving mode can be effectively suppressed, and the power consumption of the electronic camera can be effectively suppressed. can do.

According to the fourth aspect of the present invention, it is not always necessary to obtain a high-quality image when performing repeated photographing at predetermined intervals to display image information on the display means. The power consumption of the electronic camera is reduced by operating a smaller number of analog / digital converters as compared with the case of performing photographing in accordance with the instruction of the means, thereby suppressing the power consumed by the analog / digital converter. Can be suppressed.

According to the fifth aspect of the present invention, the arithmetic means adds each digital value output from each analog / digital conversion means, and adds the added value to the analog / digital signal during operation.
Because it is configured to divide by the number of operations of the digital conversion means and output as the digital image information,
By adding the respective digital values output from the respective analog / digital converters, it is possible to prevent the number of bits of the output terminal for outputting the digital image signal of the arithmetic unit from increasing, thereby preventing the configuration of the arithmetic unit from becoming complicated. be able to.

[Brief description of the drawings]

FIG. 1 is a front view of a digital camera according to an embodiment of the present invention.

FIG. 2 is a rear view of the digital camera in FIG. 1;

FIG. 3 is a side view of the digital camera of FIG. 1;

FIG. 4 is a bottom view of the digital camera in FIG. 1;

FIG. 5 is a block diagram illustrating an internal configuration of the digital camera in FIG. 1;

FIG. 6 is a block diagram illustrating a configuration of an image processing unit.

FIG. 7 is a diagram showing display contents when an operation mode of the LCD is set.

FIG. 8 is a block diagram illustrating a configuration of a signal processing circuit.

FIG. 9 is a flowchart illustrating a process of determining the number of operations of the signal processing unit by the overall control unit.

[Explanation of symbols]

 Reference Signs List 61 signal processing unit 61a CDS circuit 61b A / D converter 62 arithmetic circuit 211 overall control unit 236 power battery 238 voltage detection unit 303 CCD 313 signal processing circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C022 AA13 AB37 AB67 AC03 AC42 AC52 AC69 AC73 5C052 AA17 AB04 AC08 GA02 GA03 GA06 GB01 GC03 GC05 GC08 GD03 GE08 5C053 FA08 FA27 GB36 JA16 KA25 LA01 LA04 LA06

Claims (6)

[Claims] 1. An electronic camera which obtains digital image information by performing analog / digital conversion on analog image information output from an imaging unit, wherein: the imaging unit; and an analog format output from the imaging unit. A plurality of analog / digital conversion means for individually performing analog / digital conversion on the image information and outputting the digital information, and adding the digital values output from the analog / digital conversion means to output the digital information as the image information in digital form An electronic camera, comprising: 2. The electronic camera according to claim 1, further comprising: a battery remaining amount detecting unit configured to detect a battery remaining amount of a battery mounted as a power supply in the electronic camera; and a battery remaining amount indicated by a detection result of the electronic remaining amount detecting unit. 2. The electronic device according to claim 1, further comprising: a first controller configured to determine an operation number of the analog / digital converters to be operated among the plurality of analog / digital converters. 3. camera. 3. An electronic camera, comprising: first input means for receiving a first switching input for switching an operation mode of the electronic camera between a normal mode and a power saving mode in which power consumption is suppressed; A function of switching the operation mode between the normal mode and the power saving mode in accordance with the first switching input input via a first input unit, wherein the operation mode is set to the power saving mode. And a second control unit for operating a smaller number of the analog / digital conversion units than the number of the analog / digital conversion units provided in the electronic camera. 3. The electronic camera according to 1 or 2. 4. An electronic camera, comprising: a display unit for displaying the digital image information in a standby state for capturing an image; a recording unit for storing the image information in a digital format; A photographing instructing means for instructing, when performing repeated photographing at predetermined intervals to display the image information on the display means, a smaller number of the analog And a third control means for operating the digital conversion means.
Electronic camera according to any one of the above. 5. The arithmetic means adds the digital values output from the analog / digital conversion means,
5. The electronic camera according to claim 1, wherein the added value is divided by the number of operating analog / digital conversion units in operation and output as the digital image information. 6. The electronic camera according to claim 1, wherein the electronic camera is a digital camera.