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Auto-focusing device, electronic camera, and auto-focusing method

A technology of automatic focusing and equipment, applied in cameras, focusing devices, televisions, etc., can solve problems such as the accuracy of deterioration detection

Inactive Publication Date: 2008-10-15
CASIO COMPUTER CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

On the other hand, however, sufficient time to wait for the total attenuation of the vibration of the focus lens must be provided, because if the time W to wait for the total attenuation of the vibration of the focus lens exceeds the time of the AF evaluation cycle, the AF evaluation value to be detected will be Contains a noise component attributable to vibrations that will degrade the accuracy of the detection of the position to bring the object into focus, especially when the drive mechanism of the focus lens using a stepper motor as the actuator contains large lost motion

Method used

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  • Auto-focusing device, electronic camera, and auto-focusing method
  • Auto-focusing device, electronic camera, and auto-focusing method
  • Auto-focusing device, electronic camera, and auto-focusing method

Examples

Experimental program
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no. 1 example

[0052]FIG. 1 is a schematic block diagram showing a digital camera (electronic camera) 1 according to a first embodiment of the present invention. The digital camera 1 has an AF function based on the contrast detection system used in the prior art as described above. Digital camera 1 includes focusing lens 2, zoom lens 3, CCD (image pickup device, image pickup device) 4, CDS / AD block 5, TG (timing signal generator) 6, CDD data preprocessing block 7, color processing (CP ) block 8, JPEG encoder 9, DRAM 10, ROM 11, RAM 12, CPU (processor) 13, image display section 14, key block 15, card interface (I / F) 16, and motor drive block 17. The card interface 16 is connected to a memory card 18 which is detachably inserted into a card slot formed in the camera body.

[0053] The focus lens 2 and the zoom lens 3 are formed of respective lens groups (not shown). The motor drive block 17 includes a focus motor 170a for driving the focus lens 2 along the optical axis of the camera, a zoom ...

no. 2 example

[0074]If the performance of the optical system including the focus lens 2 and the zoom lens 3 is such that the object can be brought into focus even when the focus lens 2 is slightly deviated from the correct focus position, and / or the vibration of the focus lens 2 during its movement can be kept To the lowest level, and thereby minimize or eliminate the influence of noise due to vibration on the AF estimate when determining the AF estimate, the AF control operation can be performed without the fine search operation described above. In this way, it is possible to detect the AF evaluation value maximum position while continuously moving the focus lens 2 and move the focus lens 2 by performing substantially the same rough search operation as described above to minimize the AF evaluation period (exposure time). Automatic focus is achieved by moving to the focus position used to bring the subject of the camera into focus.

[0075] The following will refer to Figure 5 To describe...

no. 3 example

[0084] In the third embodiment, the CPU 13 follows the timing described below, in the above reference for the first embodiment figure 2 In the coarse search operation in steps S2 to S6, or in the above reference for the second embodiment Figure 5 In the focus search operation of steps T2 to T6, a processing operation for exposure is performed in step S4 (T4).

[0085] Figure 7 is corresponding to image 3 A detailed timing chart of the autofocus control operation of the third embodiment. For the rough search (focus search) operation of the third embodiment, the exposure operation of the CCD 4 is performed in synchronization with the drive cycle (drive pulse) of the focus lens 2 in such a manner that the start timing of the AF evaluation cycle and the focus The timings at which the motor 170a drives the focus lens 2 always coincide with each other. Although the operation of driving the focus lens 2 and the exposure operation of the CCD 4 are performed at different cycles,...

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Abstract

The CPU (13) continuously moves a focusing lens (2) along an optical axis by supplying a control signal to a motor driver (171a) to start continuously driving a focusing motor (stepping motor) (170a). The CPU (13) calculates an AF evaluation value based on high frequency components contained in an image signal output from a CCD (4) by driving the CCD (4) to operate for exposure with a predetermined period while continuously moving the focusing lens (2) and moves the focusing lens (2) to a position that maximizes the AF evaluation value.

Description

technical field [0001] The present invention relates to an autofocus device for a camera, such as a digital camera, to an electronic camera, and to an autofocus method. Background technique [0002] The contrast detection system (contrast detection system) is generally applied to the automatic focus of a digital camera that picks up an image of a target through a CCD-type or MOS-type solid-state image pickup device, converts the picked-up image into image data, and records the obtained image data control (AF). This system is being used in a wide variety of cameras, including digital cameras and conventional cameras that use film and use a CCD as a distance sensor. With the contrast detection system, the focus lens is driven by a stepping motor to move intermittently along the optical axis of the camera to perform exposure operations at a plurality of positions. An AF evaluation value is calculated for each position from a high-frequency component contained in an output sig...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04N5/232G03B13/36G02B7/28G02B7/36H04N101/00
CPCH04N5/23212H04N23/673H04N23/63H04N23/67
Inventor 隅秀敏
Owner CASIO COMPUTER CO LTD
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