JP2003338979A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To hardly cause incongruity feeling during playback, even when the reference clock of an imaging system for prolonging the life time of power supply voltage goes down, such as decrease in battery performance or the like. <P>SOLUTION: Two types of reference clocks of imaging system (24 MHz, 12 MHz) are provided. In a motion picture imaging mode, when storing a motion picture, the clock is operated at 24 MHz, when displaying a through image, the clock is operated at 12 MHz, and the same line is drawn two times so as to match the frame rate during an operation at 12 MHz with the reference clock of a playback system fixed at 24 MHz, thus enabling reduction in power consumption during displaying the through picture. furthermore, the battery life time can be prolonged, by changing the reference clocks depending on the remaining amount of the battery normally, by making the reference clock operate at 24 MHz, and changing the reference clock to 12 MHz, when a predetermined threshold or below is reached). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup unit for picking up an image by a solid-state image pickup device and photoelectrically converting it to obtain analog image data; And a display device that records the digital image data and displays the digital image data.

[0002]

2. Description of the Related Art Conventionally, in an image pickup device, particularly a digital camera, when a still image or the like is photographed using a CCD (Charge Coupled Device), the image data is analog-digital converted and then set in a preset compression format ( For example, JP
It is recorded and saved in a recording medium such as a memory card in a state of being compressed by EG).

By the way, an object to be imaged by a CCD is generally displayed on an LCD (liquid crystal display device) provided on the back side of a digital camera. Shooting is performed by setting the angle of view while looking at the image displayed on the LCD and operating the release button.

In digital cameras, the number of CCD pixels has been dramatically improved. Although the image quality is improved by the increase in the number of pixels, it is delayed at the conventional processing speed. Therefore, the frequency of the reference clock of the imaging system is increased without reducing the processing speed.

By the way, when the frequency of the reference clock is increased, power consumption is accelerated. Therefore, when a through image display for setting the angle of view is performed, the power is automatically turned on by the power maintenance function of the digital camera. There was an inconvenience to be blocked.

Therefore, conventionally, it has been proposed to lower the reference clock of the image pickup system when the battery power supply voltage becomes lower than a predetermined value (for example, Japanese Patent Laid-Open No. 9-16).
3238). Thereby, the life of the battery can be extended.

[0007]

However, in the above-mentioned prior art, the followability of a through image becomes poor. Also, especially when capturing a moving image, if the reference clock of the image capturing system is lowered, the frame rate changes, so there is a sense of incongruity during playback of this movie compared to normal (during operation playback when the battery is sufficient). You will feel it.

In consideration of the above facts, the present invention provides an image pickup apparatus that does not cause a feeling of strangeness during reproduction even when the reference clock of the image pickup system for extending the life of the power supply voltage is down due to a low battery. The purpose is to obtain.

[0009]

According to a first aspect of the present invention, there is provided an image pickup section for picking up an image by a solid-state image pickup element and photoelectrically converting the image to obtain analog image data. An image pickup apparatus configured to create image data, record the image data on a recording medium, and display the digital image data, wherein at least two types of reference clocks are used as synchronization signals at the time of image pickup in the image pickup unit. And a thinning rate setting means for setting a thinning rate of a synchronization signal for display on the display device based on the reference clock selected by the reference clock generating means, Image data transmission control for transmitting the digital image data to the display device based on the thinning rate set by the thinning rate setting means. It has a stage, a.

According to a second aspect of the present invention, in the first aspect of the present invention, the reference clock generating means displays an image pickup state on a display device in substantially real time in order to set an angle of view in the image pickup section. When displaying a through image,
It is characterized in that a different reference clock is generated at the time of image capturing in which the analog image data is captured by the image capturing unit.

According to a third aspect of the invention, there is provided the invention according to the second aspect, wherein the image capturing time is a moving image capturing time.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the thinning rate setting means maintains the followability of the live view display at the time of capturing a moving image. It is characterized by setting the thinning rate.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a control system in a digital camera 10 according to this embodiment. The digital camera 10 is provided with an image pickup section 18. The imaging unit 18 is provided with a lens 18A, a mechanical shutter, and a diaphragm (not shown), and makes light incident from the lens 18A enter the CCD 18B through the diaphragm when the mechanical shutter is open. It is a composition.

The digital camera 10 also has a strobe 1
2 is provided, and if necessary, the flash control unit 14 controls the light to be emitted manually or automatically.

Each control device including the image pickup section 18 and the strobe control section 14 of the digital camera 10 is connected by a bus 16 and its operation is controlled by a CPU 20. Each control device is a battery 2
Power is supplied from 2 and it is operable.

The bus 16 has a system memory (RAM or ROM) 24 and a volatile memory (S) as control devices.
A DRAM) 26, a timer function unit 28, and a calendar / clock function unit 30 are respectively connected.

An I / O port 32 is connected to the bus 16, and an I / O port 32 from an operation / display system 36 attached to a housing 34 (see FIG. 2) of the digital camera 10 is used. Signals are input and output.

As shown in FIG. 2A, a liquid crystal monitor (LCD) 38 is arranged on the back side of the housing 34 of the digital camera 10 (the side opposite to the side on which the image pickup section 18 is arranged). It is set up.

As an operation / display system, on the right side of the LCD 38 on the back side of the housing 34, there are circular up / down / left / right keys 42 used for frame switching of images displayed on the LCD 38, item selection, and the like. It is arranged. By tilting the axis of the circular up / down / left / right key 42 up / down / left / right, contact points of different switches are switched when tilted, and the switching signal is input to the I / O 32 (see FIG. 1). It has become.

Below the up / down / left / right keys 42, a menu button 44, an execute button 46, and a cancel button 48 are arranged vertically from the top. A release button 50 and a mode setting dial 52 are provided on the upper surface of the housing 34.

When the mode setting dial 52 and the menu button 44 are operated, for example, a setup screen 54 for making various settings is displayed on the LCD 38.

The execute button 46 is operated when the function is selected by the up / down / left / right keys 42 on the setup screen 54, and the cancel button 48 is operated when the selected function is canceled.

Further, as shown in FIG. 2B, an opening 60 through which the lens 18A of the image pickup section 18 can be exposed is provided on the front surface of the housing 34 of the digital camera 10. A disc-shaped barrier 62 is attached to the opening 60. This barrier 62 is used for the digital camera 10.
A drive system that can move to a position where the opening 60 is closed and a position where the opening 60 is opened (see arrow A in FIG. 2B) is provided in conjunction with the operation of the power switch 64 (see FIG. 2A). ing.

That is, when the power is off, the barrier 62 closes the opening 60 to protect the lens 18A, and when the power is on, the barrier 62 opens the opening 60.
By evacuating from, it becomes possible to take a picture.

As shown in FIG. 1, a memory card slot 60 to which a memory card 58 as a recording medium can be attached / detached is connected to the bus 16 via a card I / F 56. The image data taken by the image pickup unit 18 is recorded in the memory card 58 loaded in the memory card slot 60.

The signal input to the image pickup section 18 is sent to the signal processing section 104, subjected to noise reduction processing, gain control, and A / D conversion section 10.
6 is sent.

The image data A / D converted by the A / D conversion unit 106 is sent to the compression / decompression unit 108 and subjected to compression processing (JPEG) in accordance with an instruction from the CPU 20, or is left as it is. In this state, it is sent to the memory card slot 60 via the card I / F 56.

The image data recorded in the memory card 58 is read out based on a reproduction display instruction from the CPU 20, stored in the frame memory 110, and the LCD control unit 1
It is displayed on the LCD 12 under the control of 12. At this time, on the LCD 112, characters, character data, and the like are superimposed and displayed together with the image display based on the image data controlled by the OSD (on-screen display unit 114).

An external I / F 116 is connected to the bus 16 and can be directly connected to an external control device (hereinafter referred to as PC 120) such as a personal computer via a connector 118. The image data recorded in the memory card 58 can be transmitted.

In addition to the LCD 112, the digital camera 10 is provided with an optical finder 66 as a monitor for checking images. Optical viewfinder 66
Is provided so as to project from the upper surface of the housing 34,
The state of FIG. 2A is the storage position (non-use position of the optical finder 66), and the state of FIG. 2B is the projecting position (use position of the optical finder 66).

Further, when the captured image is displayed on the LCD 112, particularly when a moving image is captured and a through image is displayed, as shown in FIG.
The side and side B storage areas 26A and 26B are provided, and CC
Image data is alternately stored for each imaging line by D18B. At this time, the storage area 2 on the side different from the storage area 26A (or 26B) in the storage operation
In 6B (or 26A), the data is sent to the frame memory 110. That is, the A side and the B side are alternately applied to storage and reproduction, and the followability is maintained.

As shown in FIG. 1, the image pickup system composed of the image pickup section 18, the signal processing section 104 and the A / D 106 operates at a predetermined reference clock.
The reference clock is sent from the timing generator 122.

Here, in this embodiment, two kinds of reference clocks (different frequencies) are selectively transmitted from the timing generator 122.

That is, the timing generator 122
Is 24.545 MHz (hereinafter referred to as 24 MHz)
And 1/2, that is, 12.725 MHz (hereinafter, 12M
It is possible to output two types of reference clocks (referred to as Hz) and are selected based on an instruction signal from the CPU. The higher the reference clock, the faster the processing speed, and the lower the reference clock, the lower the power consumption. Note that the reference clock for the systems other than the imaging system, that is, the reproduction system is fixed at 24 MHz.

Here, the processing speed is determined by performing thinning processing at each of 24 MHz and 12 MHz, for example, 1/2 thinning, 1/4 thinning, 1
Table 1 shows each processing speed in the case of / 8 thinning.

[0036]

[Table 1]

In the case of Table 1 above, as a reference clock, for example, when 24 MHz is used by decimating 1/2,
It can be seen that the processing speed at 30 MHz is the same as the case where 2 MHz is used by 1/4 thinning.

In the present embodiment, the fact that the frame rates are the same is used separately for the reference clock when capturing a moving image and the reference clock when reproducing a through image.

That is, in the digital camera 10,
24 MHz as the reference clock VI when capturing a moving image
Instruct to halve z. On the other hand, as the reference clock VD for displaying a through image, 1/4 of 12 MHz
Instruct thinning.

On the other hand, the reference clock of the reproduction system is 24 MH
It is fixed at z. For example, when the reference clock of the imaging system is 12 MHz, there are 240 capture lines, but 480 display lines are required (see Table 2).

[0041]

[Table 2]

Therefore, during reproduction of a through image, the LCD control unit 112 writes so-called twice (continuously scans the same line twice) at the time of encoding (encoding) to match the frame rates (see FIG. 4). ). In this case, LC
In the display image at D38, the phenomenon that the vertical resolution is slightly lowered occurs, but basically the LC with a small screen size is used.
In D38, there is no visual problem. It should be noted that, as the actual digital image data, the high image quality state is maintained, and therefore, for example, it does not affect the reproduced image when the image data is transferred to the PC 120.

By switching the reference clocks as described above, it is possible to prevent the power consumption from being lowered due to an unnecessary increase of the reference clocks and to achieve the contradictory objectives of maintaining the followability of the live view display. it can.

The operation of this embodiment will be described below.

Before taking a picture with the digital camera 10,
Operate the mode setting dial 52 to set up screen 5
4 is displayed on the LCD 38.

On the setup screen, items such as the recording mode, the number of pixels, the sharpness, and the beep sound are selected as necessary, and the photographing conditions are set.

In the photographing mode, the image pickup unit 1 is displayed on the LCD 38.
The preview taken in 8 is displayed, and when the predetermined angle of view is determined, the release button 50 is operated and the shooting is executed.

In this case, the data picked up by the image pickup section 18 is sent to the signal processing section 104, subjected to processing such as noise reduction processing and gain control, and then A / D converted to generate digital image data. To do.

Thereafter, the compression / expansion unit 108 compresses the digital image data and records it on the memory card 58.

In the reproduction mode, when the index mode is selected, the thumbnail image is read from the digital image data recorded in the memory card 58, and the LCD is displayed.
As the index image, the captured image is displayed in a matrix. Further, when the 1-image reproduction mode is selected, the compressed image data is read out and decompressed by the compression / decompression unit 108, and the frame memory 11 is read.
After being expanded to 0, it is displayed on the LCD 38.

Here, in the present embodiment, the reference clock of the image pickup system is changed according to the usage status of the digital camera. This change of the reference clock is executed by the control of the timing generator 122 by the instruction signal from the CPU 20.

The change of the reference clock is when the moving image is picked up as the first usage state, and when the power (battery) remaining amount is lowered as the second usage state. (First usage situation) That is, during operation imaging, there are actual data acquisition and live view display. If the reference clock is kept high during live view display, power consumption will progress rapidly. Even though there is still enough power to capture a moving image, automatic shutdown is performed due to low battery. Therefore, when reproducing a through image, the reference clock is set to the normal 24 MHz.
By lowering from z to 12 MHz, the curve of power consumption is made gentle. Here, the problem is the followability of the reproduced image of the through image due to the decrease of the reference clock. However, in the present embodiment, in order to maintain this tracking capability, the thinning rate and the number of captured lines are set in accordance with the set reference clock, and the line writing to the frame memory for displaying on the LCD is performed by the reproduction system. It is adapted to the reference clock (24 MHz).

Hereinafter, according to the flowchart of FIG. 5, the first
The reference clock change control in the usage state of will be described.

In step 200, it is determined whether or not the mode is the moving image capturing mode, and if an affirmative determination is made, the process proceeds to step 202, the imaging system reference clock is set to 24 MHz, and the process proceeds to step 204. In step 204, the thinning rate is set to 1/2, the process proceeds to step 206, and the number of fetched lines is set to 480. Further, in the next step 208, the encoding in the LCD control unit 112 is set to 1 time.

As a result, the image pickup system operates with the reference clock whose processing speed has the highest priority and coincides with the reference clock of the reproducing system, so that the functions of the digital camera can be maximized.

At the next step 210, the mode is shifted to the moving image capturing mode after the above setting is completed.

Next, when a negative determination is made in step 200, the process proceeds to step 212, the imaging system reference clock is set to 12 MHz, and the process proceeds to step 214. In step 214, the thinning rate is set to 1/4 and step 2
Moving to 16, the number of fetched lines is set to 240.
In the next step 218, the encoding in the LCD control unit 112 is set to double.

As a result, the processing speed of the image pickup system is half that at the maximum, but the processing speed at the maximum can be maintained by setting the thinning rate to 1/4 and the number of fetched lines to 240. did.

Further, the encoding of the LCD control section 112 is set to double so that the processing speed corresponds to the reference clock of the reproducing system. That is, when the 240 captured images are reproduced as they are during the through image display, the followability with respect to the captured image is deteriorated. Therefore, by writing the taken-in line twice, the number of lines becomes the same and the followability can be maintained.

At the next step 220, the mode is shifted to the live view display mode after the above setting is completed.

The steps 210 and 2
When a mode switching operation is performed during each mode transitioned in step 20, this routine is interrupted and the setting according to the mode is executed. (Second usage status) When the remaining power level is the second usage status, the display on the LCD 38 is automatically cut off when the power level drops further, and it is more than necessary before the battery conservation function works. The reference clock is changed in order to reduce the power consumption. That is, the reference clock is changed only by the preset threshold value of the remaining amount of power (battery) irrespective of a specific state such as when capturing a moving image as in the first usage state. Hereinafter, the reference clock change control in the second usage state will be described with reference to the flowchart of FIG.

At step 250, it is judged if the remaining battery level is below the threshold value. This threshold value may be set in advance or may be set by the user, but generally, the remaining amount of about 30% of the total battery capacity is set as the threshold value. It is preferable.

When a negative determination is made in step 250, it is determined that the remaining battery level is sufficient, and the process proceeds to step 252, the image pickup system reference clock is set to 24 MHz, and the process proceeds to step 254. In step 254, the thinning rate is set to 1/2, and the process proceeds to step 256 to set the number of fetched lines to 480. Further, in the next step 258, the encoding in the LCD control unit 112 is set to 1 time.

As a result, the image pickup system operates with the reference clock having the highest processing speed and coincides with the reference clock of the reproducing system, so that the function of the digital camera can be maximized.

Next, when the affirmative judgment is made in Step 250, it is judged that the battery remaining amount is small, and Step 2
In step 60, the image pickup system reference clock is set to 12 MHz, and then step 262 is performed. In step 262,
The thinning rate is set to 1/4, the process proceeds to step 264, and the number of fetched lines is set to 240. Further, in the next step 266, the encoding in the LCD control unit 112 is set to double.

As a result, the processing speed in the image pickup system is half that at the maximum, but the processing speed at the maximum can be maintained by setting the thinning-out rate to 1/4 and the number of fetched lines to 240. did.

Further, the encoding of the LCD control unit 112 is set to double so that the processing speed corresponds to the reference clock of the reproducing system. That is, when the 240 captured images are reproduced as they are during the through image display, the followability with respect to the captured image is deteriorated. Therefore, by writing the taken-in line twice, the number of lines becomes the same and the followability can be maintained.

In this way, when the remaining battery capacity falls below the predetermined threshold value, the reference clock of the image pickup system is lowered,
The battery life can be extended because the battery can be preserved.

In the above embodiment, two kinds of reference clocks of the image pickup system, 24 MHz and 12 MHz, are applied,
Although the number of steps is changed by the timing generator in two steps, the number of steps may be increased. Also, the thinning rate applied is 1/2 thinning and 1/4 thinning,
Other decimation rates may be applied as long as they are matched with the reference clock of the reproduction system.

As described above, in the present embodiment,
Two types of reference clocks for the imaging system (24MHz, 12MH
z) Prepare and operate at 24 MHz when storing a moving image in moving image capturing mode, at 12 MHz when displaying a through image, and at a fixed frame rate of 24 MHz when operating at 12 MHz. Since the same line is written twice to match the reference clock of the system, power consumption during live view display can be reduced. In addition, by performing such a change of the reference clock according to the remaining amount of the battery (normally, the reference clock is operated at 24 MHz, and when the threshold value is lower than a predetermined threshold value, the reference clock is changed to 12 MHz. ), Battery life can be extended.

[0071]

As described above, according to the present invention, even when the reference clock of the image pickup system for extending the life of the power supply voltage is down due to a decrease in battery or the like, almost no discomfort is felt during reproduction. Has excellent effect.

[Brief description of drawings]

FIG. 1 is a control block diagram of a digital camera according to an embodiment.

FIG. 2A is a perspective view of the external appearance of the digital camera as seen from the back side, and FIG. 2B is a perspective view as seen from the front side.

FIG. 3 is a block diagram showing a flow of image pickup data displayed on an LCD by an image pickup unit.

FIG. 4 is a timing chart of reference clocks of an image pickup system and a reproduction system.

FIG. 5 is a flowchart showing a reference clock change control routine at the time of capturing a moving image.

FIG. 6 is a flowchart showing a reference clock change control routine at the time of low battery.

[Explanation of symbols]

10 Digital Camera (Imaging Device) 16 Bus 18 Imaging Unit 18B CCD (Imaging System) 20 CPU (Thinning-out Ratio Setting Unit, Image Data Transmission Control Unit) 22 Battery 38 LCD (Display Device) 104 Signal Processing Unit (Imaging System) 106 A / D (imaging system) 110 frame memory (reproduction system) 112 LCD control unit (reproduction system) 122 timing generator (reference clock generation means)

Claims (4)

[Claims] 1. An image pickup unit for picking up an image by a solid-state image pickup device and photoelectrically converting it to obtain analog image data; and an analog-digital conversion of the analog image data to create digital image data, which is recorded on a recording medium. An image pickup apparatus comprising: a display device for displaying digital image data; and a reference clock generation means for selectively generating at least two types of reference clocks as synchronization signals at the time of image pickup in the image pickup section, Based on the reference clock selected by the reference clock generating means, based on the thinning rate set by the thinning rate setting means for setting the thinning rate of the synchronizing signal for display on the display device, and the thinning rate set by the thinning rate setting means. Image data sending control means for sending the digital image data to a display device. 2. The reference clock generating means displays the image pickup state on the display device in almost real time in order to set the angle of view in the image pickup section, and at the time of displaying the analog image data in the image pickup section. The image pickup apparatus according to claim 1, wherein different reference clocks are generated during image pickup. 3. The image pickup apparatus according to claim 2, wherein the image pickup time is a moving image pickup time. 4. The imaging according to claim 1, wherein the thinning-out rate setting unit sets a thinning-out rate that maintains the followability of a through image display when capturing a moving image. apparatus.