JP2003050344A - Electronic camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the response of an AF operation in setting the stoppage of the operation of an image display monitor for an electronic camera. SOLUTION: Whether an automatic focusing operation control is performed based on an image signal outputted from a CCD 4, or based on a signal outputted from a range finder part A 30 or a range finder part B 40 is selected by a CPU-A 1 based on the decision result whether or not a power necessary to actuate an image pickup system equipped with an image pickup part 4 for driving the CCD 4 and a CPU-B 9 for processing the image signal outputted from the imaging device is supplied by a power supply circuit 27. By having such the constitution, it becomes unnecessary to temporarily wait for the automatic focusing operation until the power supply operation is stabilized after starting to supply the power to the image pickup system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique used in an electronic camera, and more particularly to a technique in which autofocus by a plurality of methods provided in an electronic camera is switched and used according to a situation.

[0002]

2. Description of the Related Art An invention relating to a technique for switching and using autofocus by a plurality of methods provided in an electronic camera according to the situation is disclosed in Japanese Patent Laid-Open No. 10-229516. This invention is an external light AF (Auto Foc
us) external light AF that moves the focus lens to the in-focus position based on the distance measured by the sensor, and AF that indicates the contrast of the image signal output from the CCD (Charge Coupled Device) sensor on which the subject image is formed The electronic camera is provided with contrast AF for moving the focus lens to the in-focus position based on the evaluation value. Then, it is possible to selectively use both AFs for normal shooting and macro shooting, or when the ambient environmental temperature is severe or when high focusing accuracy is required, the external light AF is performed first, and then the contrast AF is continuously performed. Is to do.

[0003]

Contrast AF used in many electronic cameras uses an image signal output from a CCD for photographing on which a subject image is formed, and evaluates the AF of the image signal. The focus lens is moved to the in-focus position based on the value. Therefore, when the CCD and the signal processing unit that processes the image signal that is the output of the CCD are operating, the contrast AF can perform the focusing operation in a short time.

By the way, in recent electronic cameras, an optical viewfinder is provided and a monitor is provided for the purpose of, for example, suppressing the power consumption due to the constant operation of the image display monitor and extending the usable time by the battery operation. Many have the function of stopping the operation of. Most of such electronic cameras reduce the power consumption even when the monitor operation is stopped. Therefore, the CCD for photographing and the signal regarding the image signal which is the output of the CCD are used except during the photographing operation. The power supply to the processing unit is also stopped.

Now, consider that the contrast AF is operated for photographing when the above-mentioned electronic camera is set to stop the operation of the monitor. FIG. 3 is a flowchart showing the processing contents of the distance measurement operation processing for the autofocus operation at the time of shooting, which is performed by the control unit of such an electronic camera.

Generally, auto-focusing at the time of photographing is performed in response to a first release (so-called half-press) operation on a release button. Therefore, the flowchart shown in FIG. 3 is started when the control unit detects the operation of the first release.

When the processing of FIG. 3 is started, first, S100
1, whether or not the power supply of the imaging system is turned on,
That is, the control unit determines whether or not electric power is being supplied to the image pickup CCD and the signal processing unit for the image signal output from the CCD.

At this time, if the power of the image pickup system is turned on (Yes in the determination result in S1001), S100 is performed.
In 4, the control for immediately executing the distance measurement processing by contrast AF, that is, the processing for calculating the movement amount of the focus lens based on the AF evaluation value indicating the contrast height of the image signal is performed.

However, if the power supply of the image pickup system is not turned on (the determination result in S1001 is No), the control unit
In step S1002, the image pickup system is turned on to supply power to the CCD and the image processing unit, and in step S1003, the progress of the control process is waited until the operations of these image pickup systems are stabilized. This is because even if the distance measurement processing by contrast AF in S1004 is performed in a state where the operation of the image pickup system is unstable, particularly when the oscillation operation of the oscillator that oscillates the operation clock used by the signal processing unit is unstable. This is because the accuracy of the value obtained as a result of cannot be expected.

As described above, when the operation stop of the image display monitor of the electronic camera is set, it is necessary to wait for the operation of the image pickup system to be stable. Therefore, from the first release to the completion of the AF operation to some extent. Therefore, there is a problem that the response of the AF operation is delayed.

In view of the above problems, it is a problem to be solved by the present invention to improve the response of the AF operation at the time of setting the operation stop of the image display monitor of the electronic camera.

[0012]

According to one aspect of the present invention, an electronic camera outputs control of an autofocus operation for moving a lens or an image sensor to focus an object image on the image sensor. A first autofocusing means for performing an autofocusing operation based on an image signal, and a second autofocusing means for controlling the autofocusing operation based solely on a signal output from a sensor used for the control, The image pickup device driving unit for driving the image pickup device, or the image signal processing unit for processing the image signal output from the image pickup device, determines whether or not the power necessary for functioning is supplied, Either one of the one autofocus means or the second autofocus means is selected based on the result of the determination. Serial to solve the problems described above by be configured to have a selection unit configured to perform control of the autofocus operation, the.

Here, the selection means selects the first autofocus means when it is determined that the power is being supplied, and the second autofocus means when it is determined that the power is not being supplied. It is advisable to select the autofocus means.

In the electronic camera according to the present invention described above, the first autofocus means may use a contrast detection method as a control method for the autofocus operation. Here, the contrast detection method is a method in which a subject image is focused on the image sensor by moving the lens or the image sensor so that the contrast of the image represented by the image signal output from the image sensor becomes high. .

In the electronic camera according to the present invention described above, the second autofocus means has an active system as a control system for the autofocus operation.
Alternatively, a passive method may be used. Here, the active method means a method of measuring a distance to a subject using light or a signal emitted from an electronic camera and moving a lens or an image pickup device based on a result of the distance measurement. There is an infrared irradiation type triangulation method that performs triangulation based on the reflected light of the infrared rays emitted from the camera.

In the passive system, the distance to the object is measured using a signal corresponding to the light from the object acquired by the sensor without emitting light or signal from the electronic camera, and the measurement is performed. It refers to a method of moving a lens or an image pickup element based on the result of the distance. For example, there is a phase difference detection method in addition to the contrast detection method described above. There is also a passive triangulation method that does not emit light from an electronic camera.

According to the above-described electronic camera of the present invention, the power supply necessary for the drive unit for driving the image pickup device or the image signal processing unit for processing the image signal output from the image pickup device to function. If not, the autofocus is not performed based on the image signal obtained by the image pickup device for shooting, but the autofocus is performed based on the signal obtained by the dedicated sensor. It is not necessary to suspend the control until the operation of the image pickup system including the image pickup unit and the image signal processing unit that processes the image signal output from the image pickup device is stabilized. Therefore, when the operation stop of the image display monitor in which the operation of the image pickup system is stopped is set,
Operation response is improved.

Further, when the power of the image pickup system is not turned on, the autofocus operation is performed by the control of the second autofocus means which generally consumes much less power than the image pickup system. It consumes less power. As a result, if this electronic camera uses a battery as a power source, there is an effect that the usable time becomes long.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an electronic camera embodying the present invention. First, the figure will be described.

CPU (Central Processing Unit) -A
A central processing unit 1 controls the operation of the entire electronic camera. EEPROM (Electrically Erasable and
The Programmable Read Only Memory) 2 stores in advance a control program for causing the CPU-A1 to control the operation of the electronic camera. The CPU-A1 executes the control program to perform the above-mentioned operation control. become.

The lens 3 is a photographing optical system for forming a subject image on the CCD 4. CCD (Charge Coupled Device
) 4 is an image sensor that photoelectrically converts the formed subject image and outputs an electric signal (analog signal) indicating the image.
The image pickup circuit 5 is a CDS (Correlated Double Sampling:
Correlated double sampling circuit) and AGC (Automatic Gain)
Control: Auto gain control circuit) and the like, and under the control of the CPU-A1, removes reset noise that may be included in the electric signal (analog signal) output from the CCD 4 and adjusts the signal level. The circuit also includes a circuit for driving the CCD 4.

The A / D converter 6 is a circuit for converting the output signal (analog signal) of the image pickup circuit 5 into digital data. The correction circuit 7 is a circuit that performs correction processing such as white balance and γ correction on a captured image represented by digital data output from the A / D conversion unit 6.

The output of the correction circuit 7 is the frame memory 8,
CPU-B9, FIFO memory 10, and recording medium I /
It is connected to F11 via a bus 12, and data can be exchanged between them under the control of the bus 12 by the CPU-B 9.

The frame memory 8 is used as a buffer memory for temporarily storing photographed images output from the correction circuit 7 and photographed images subjected to image processing by the CPU-B9, and various processes by the CPU-B9. Is a memory that is also used as a work storage area for.

The CPU-B9 is an arithmetic unit for performing image processing of a photographed image under the control of the CPU-A1, and manages the frame memory 8 (frame memory control function) in accordance with a control program provided inside itself. , Expansion processing of compressed image data (image expansion function), data compression processing for captured images (image compression function), control processing of access to the recording medium 21 for writing and reading data (recording medium access function) ), And an AF evaluation value calculation process (contrast AF distance measuring function) that indicates the height of the contrast of the captured image. In addition, in the compression processing and the expansion processing of the image data, for example, JPEG
(Joint Photographic Experts Group) method compression and decompression are performed.

First-in first-out (FIFO) memory 1
Reference numeral 0 denotes a memory for temporarily storing image data expressing an image to be displayed, and stores image data after being subjected to image processing by the CPU-B9. Recording medium I / F
Reference numeral 11 provides an interface function for exchanging data with the recording medium 13, and processing of writing data to the recording medium 13 or reading data from the recording medium 13 is performed.

The recording medium 13 holds recorded data, and a removable recording medium such as a memory card having a built-in semiconductor memory is convenient for an electronic camera. The video encoding circuit 14 is a CPU-A.
Under the control of No. 1, it is a circuit for superimposing on-screen information such as a date on an image represented by the data read from the FIFO memory 10.

The video output circuit 15 is a circuit for converting the digital image data output from the video encoding circuit 14 into a video signal (image signal) which is an analog signal. The video output terminal 16 is a terminal for outputting the video signal output from the video output circuit 15 to the outside of the electronic camera.

The TFT (Thin Film Transistor) liquid crystal driving circuit 17 is a TFT based on the image signal output from the video encoding circuit 14 under the control of the CPU-A1.
This is a circuit that drives the panel 18. TFT panel (TF
The T liquid crystal panel) 18 is used as a liquid crystal monitor that is driven by the TFT liquid crystal drive circuit 17 and displays an image represented by an image signal output from the video encoding circuit 14.

This electronic camera is equipped with an optical finder (not shown), and it is possible to photograph a subject image without displaying the subject image formed on the CCD 4 on the liquid crystal monitor. Therefore, this electronic camera has a configuration in which the user can set whether to operate the liquid crystal monitor.

The backlight unit 19 forms a liquid crystal monitor together with the TFT panel 18,
The unit is provided with a light source for illuminating the liquid crystal portion of the TFT panel 18 from its rear surface under the control of the CPU-A1. As this light source, for example, a white LED (Light Emit)
ting Diode) or the like is used.

The actuator 20 is an operating device such as a motor (AF motor, zooming motor, etc.) for driving the lens (shooting optical system) 3, a mechanical shutter drive device, etc., and the actuator drive circuit 21.
Driven by. The actuator drive circuit 21 is a CPU
-A1 is a circuit for driving the actuator 20 under the control of A1. During the autofocus operation, the AF motor of the actuator 20 operates based on the information from the CPU-A1 indicating the distance from the electronic camera to the subject. Then, the lens 3 is moved and the subject image is CCD
Focus at 4.

The external data I / F 22 provides an interface function for exchanging data between an external device such as a personal computer and the CPU-A1, and is of a USB (Universal Serial Bus) type, for example. I / F. The key matrix unit 23 is a matrix of various keys, switches, buttons, etc. for receiving various instructions from the user and notifying them to the CPU-A1. A release button operated to cause the electronic camera to perform an image capturing operation is also included in the key matrix unit 23, and the CPU-A1
It is possible to detect the operation of the 1st release (so-called half press) and the 2nd release (so-called full press) of the release button.

The LCD display circuit 24 is a circuit for driving the LCD panel 25 under the control of the CPU-A1. LC
The D panel 25 is driven by the LCD display circuit 24,
Display according to the drive signal, for example, display of various setting states of the electronic camera such as exposure and shutter speed, and display of the number of images that can be captured and recorded at present are performed.

The battery 26 is a power source for supplying electric power to this electronic camera. The power supply circuit 27 is a circuit that controls the voltage supplied from the battery 26 and supplies power to each unit of the electronic camera. When the electronic camera is set so as not to operate the liquid crystal monitor in accordance with the instruction from the CPU-A1, the power supply circuit 27 except for the period until the control process performed in response to the release operation is completed. The power supply to each of the components indicated by the symbols 4 to 19 shown in FIG.

Further, in this electronic camera, the distance measuring section A30 exclusively used for measuring the distance to the object using the object light flux (external light) which is not the light transmitted through the lens 3.
Alternatively, the distance measuring unit B40 is provided, and the so-called external light type AF can be performed.

The distance measuring unit A30 is for performing so-called active distance measurement. Here, the light projecting unit 31 irradiates the subject with infrared light and reflects the light reflected by the subject and returned. The light receiving unit 32 receives the light, and the light projecting unit 31 and the light receiving unit 3
Infrared irradiation light type triangulation is performed in which the distance to the object is calculated by the distance measurement calculation unit A33 on the basis of the angle formed by the two.

The distance measuring unit B40 is for performing so-called passive distance measuring. Here, the light from the subject is received by each of the right light receiving unit 41 and the left light receiving unit 42, and the light received by them is received. A phase difference detection type distance measurement is performed in which the distance measurement calculation unit B43 obtains the distance to the subject based on the difference in the intensity distribution of.

As the passive distance measuring, the light from the object is received by each of the right light receiving portion 41 and the left light receiving portion 42, and the distance to the object is calculated based on the difference in the light receiving angle between them. The distance measurement unit B40 may perform the triangular distance measurement that is obtained in B43.

Next, in the electronic camera having the above-described structure, of the control processing for this electronic camera performed by the CPU-A1, the AF operation at the time of shooting related to the present invention is performed.
The processing content of the distance measurement operation processing for the operation will be described. FIG. 2 is a flowchart showing the processing contents of this distance measuring operation processing. The process shown in the figure is realized by the control program stored in the EEPROM 2 being read by the CPU-A 1 and executed, and is started when the 1st release operation on the release button is detected.

When the 1st release for the release button is detected, it is determined in S101 whether or not the power supply of the image pickup system is turned on, that is, the power to each component indicated by the symbols 4 to 19 shown in FIG. The CPU-A1 determines whether or not the power supply circuit 27 is supplying the power. Then, as a result, if the power supply of the image pickup system is turned on (the determination result of S101 is Yes), the process proceeds to S102, and the power supply of the image pickup system is not turned on (S10).
If the determination result of 1 is No), the process proceeds to S103.

The power supply circuit 27 stops the supply of electric power to the respective components indicated by the symbols 4 to 19 because the electronic camera described above has the liquid crystal monitor (TFT panel 18 and backlight unit 19). ) Is set not to operate, the CPU-A1 may determine the current setting state of the operation of the liquid crystal monitor in the determination process of S101.

In S102, the CPU-A1 causes the CPU-B9 to perform a distance measurement process by contrast AF, that is, a process of calculating an AF evaluation value indicating the contrast height of the subject image currently formed on the CCD 4. That AF
The evaluation value is acquired, and the processing for obtaining the distance from the electronic camera to the subject is performed based on the AF evaluation value, after which the distance measuring operation processing is terminated.

On the other hand, if the determination result of the determination processing of S101 is No, in S103, CPU-A
Reference numeral 1 gives the power supply circuit 27 an instruction to supply power to one of the distance measuring units A30 or B40 provided in this electronic camera. Generally, the operations of the distance measuring unit A30 and the distance measuring unit B40 immediately after the power is turned on are from 4 to 19 shown in FIG.
Since it stabilizes in a much shorter time than the operation of each component indicated by the symbol, the distance measuring unit A30 and the distance measuring unit B40
It is not necessary for the CPU-A1 to intentionally perform the processing of waiting for the progress of the control processing such as S1003 in FIG. 3 until the operation of FIG.

In subsequent S104, the CPU-A1 measures the distance from the electronic camera to the subject by the distance measuring unit A30.
Alternatively, the distance measuring unit B40 is caused to perform processing for acquiring information indicating the distance, and thereafter, this distance measuring operation processing is terminated. By the control processing by the above CPU-1,
When the power of the image pickup system is not turned on, contrast AF using the image signal obtained by the CCD 4 for photographing is not performed, but AF operation based on the distance measurement by the distance measuring unit A30 or the distance measuring unit B40 is performed. As a result, it is not necessary to temporarily stop the control until the operation of the image pickup system becomes stable, and the response of the AF operation when the operation stop of the image display monitor of the electronic camera is set is improved. When the power of the image pickup system is not turned on, the AF operation is generally performed using the distance measuring unit A30 or the distance measuring unit B40, which consumes much less power than the image pickup system. It consumes less. As a result, there is an effect that the usable time of this electronic camera using the battery 26 as a power source becomes long.

Although the AF operation is realized by controlling the position of the lens 3 in this embodiment, the AF operation is performed by fixing the lens 3 and moving the position of the CCD 4. It may be realized.

[0047]

As described above in detail, in the electronic camera according to the present invention, the control of the autofocus operation is performed based on the image signal output from the image pickup device for photographing, or exclusively. A drive unit that drives the image pickup device, and an image signal processing that processes an image signal output from the image pickup device, whether to perform selection based on a signal output from a sensor used for the control. The image display in which the operation of the imaging system is stopped is performed because the control is performed based on the determination result of whether or not the power required for the imaging system including the The response of the autofocus operation when the monitor monitor operation stop setting is improved, and
This has the effect of reducing the power consumption of this electronic camera.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an electronic camera embodying the present invention.

FIG. 2 is a flowchart showing the processing contents of distance measurement processing for autofocus operation at the time of shooting performed by the CPU-A.

FIG. 3 is a flowchart showing processing contents of distance measurement operation processing for autofocus operation at the time of shooting in a conventional electronic camera.

[Explanation of symbols]

1 CPU-A 2 EEPROM 3 lenses 4 CCD 5 Imaging circuit 6 A / D converter 7 Correction circuit 8 frame memory 9 CPU-B 10 FIFO memory 11 Recording medium I / F 12 buses 13 recording media 14 Video encoding circuit 15 Video output circuit 16 video output terminals 17 TFT LCD drive circuit 18 TFT panel 19 Backlight unit 20 actuators 21 Actuator drive circuit 22 External data I / F 23 Key matrix section 24 LCD display circuit 25 LCD panel 26 batteries 27 Power circuit 30 Distance measuring unit A 31 Projector 32 Light receiving part 33 Distance measuring unit A 40 Distance measuring unit B 41 Right receiver 42 Left receiver 43 Distance measuring unit B

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 5/232 G02B 7/11 DB // H04N 101: 00 A G03B 3/00 A

Claims (5)

[Claims] 1. A first autofocus means for controlling an autofocus operation for moving a lens or an image pickup device to focus an object image on the image pickup device based on an image signal output from the image pickup device. A second autofocus means for controlling the autofocus operation based solely on a signal output from a sensor used for the control, an image pickup element drive section for driving the image pickup element, or the image pickup element From the first autofocus means or the second autofocus means to determine whether or not the power necessary for the image signal processing unit that processes the image signal output from the device has been supplied. Selecting means for selecting either of the two based on the result of the determination to control the autofocus operation. An electronic camera, characterized in that it comprises a. 2. The selection means selects the first auto focus means when it is determined that the power is being supplied, and the second auto focus means when it is determined that the power is not being supplied. The electronic camera according to claim 1, wherein the focus means is selected. 3. The electronic camera according to claim 1, wherein the first autofocus means uses a contrast detection method as a control method for the autofocus operation. 4. The electronic camera according to claim 1, wherein the second autofocus means uses an active system as a control system for the autofocus operation. 5. The electronic camera according to claim 1, wherein the second autofocus means uses a passive system as a control system for the autofocus operation.