CN101360188A - Focusing system and focusing method - Google Patents
Focusing system and focusing method Download PDFInfo
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- CN101360188A CN101360188A CNA2007102012677A CN200710201267A CN101360188A CN 101360188 A CN101360188 A CN 101360188A CN A2007102012677 A CNA2007102012677 A CN A2007102012677A CN 200710201267 A CN200710201267 A CN 200710201267A CN 101360188 A CN101360188 A CN 101360188A
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Abstract
The invention provides a focusing system and a focusing method. The focusing system comprises a lens, a charge-coupled device, an actuator, an exposure control unit and a focus requester. The focusing system is in a luminous environment produced by a power supply with a predetermined cycle. The exposure control unit is used to control the charge-coupled device to adopt the preset exposure time at a plurality of focusing positions for exposure so as to acquire multi-frame pictures. The preset exposure time is n/2 times of the predetermined cycle and is smaller than the vertical synchronizing cycle of the charge-coupled device, wherein, n is a natural number. Because the luminance variation cycle in the luminous environment produced by the power supply with the predetermined cycle is one second of the predetermined cycle, the focusing system executes the focusing method that brightness values of the multi-frame pictures obtained by adopting the preset exposure time at a plurality of focusing positions for exposure are always the same, contrast ratios of the multi-frame pictures alter following change laws of the focusing positions, and the optimum focusing position can be obtained through comparing the contrast ratios of the multi-frame pictures by the focus requester so as to realize correct focusing.
Description
Technical field
The present invention relates to camera technique, particularly a kind of focusing system and focusing method.Background technology
At present, the charge-coupled device of digital camera/Digital Video (Charge Coupled Device, vertical sync period CCD) mostly is 1/30 second, about 33.33 milliseconds (millisecond, ms).And there is the electrical network of two kinds of frequencies in the world: 50 hertz and 60 hertz.See also Fig. 6, the sequential schematic diagram of in the luminous environment that 50 hertz of power supplys (cycle is 20ms) produce, focusing for digital camera/Digital Video.Reference axis 99 is time shaft (t), and curve 98 is the brightness change curve of luminous environment.At a plurality of focusing position P
1~ P
k(k is a natural number, down together) adopts identical time for exposure Yms exposure, the brightness L of the multiframe picture of acquisition
1~ L
kMay not be identical.The brightness L of multiframe picture
1~ L
kWhether identically depend on time for exposure Yms, and time for exposure Yms changes with the bright-dark degree of luminous environment usually, so situation about occurring is usually: the brightness L of multiframe picture
1~ L
kInequality, film flicker.See also Fig. 7, for digital camera/Digital Video is focused a kind of brightness that obtains and contrast response curve schematic diagram in the luminous environment that 50 hertz of power supplys produce.The residing focusing position P of reference axis 97 expression digital camera/Digital Video
1~ P
k, reference axis 96 characterizes the contrast of picture, and reference axis 95 characterizes the brightness of picture, and curve 94 is the luminosity response of picture, and curve 93 is the contrast response curve of picture.As seen, if the brightness L of multiframe picture
1~ L
kInequality, its contrast C then
1~ C
kWill be with brightness fluctuation, cause digital camera/Digital Video can't be by the contrast C between contrast multiframe picture
1~ C
kDetermine the correct focusing of best focusing position realization exactly.
Summary of the invention
In view of this, be necessary to provide a kind of focusing system and the focusing method that in the luminous environment that the power supply of predetermined period produces, can correctly focus.
A kind of focusing system, it comprises camera lens, charge-coupled device, actuator, exposure control unit and asks burnt device.This camera lens is used for the photographed scene optical imagery, and this photographed scene is in the luminous environment that the power supply of predetermined period produces.This charge-coupled device is used for the imaging signal of this camera lens of sensing and is converted into the picture of electrical signal form.This actuator is used to drive this camera lens and travels through a plurality of focusing positions.This exposure control unit is used to control this charge-coupled device and adopts default time for exposure to realize electronic shutter function at each focusing position, to obtain multiframe picture that should a plurality of focusing positions.It should be n/2 times of this predetermined period and less than the vertical sync period of this charge-coupled device, wherein, n is a natural number default time for exposure.This asks burnt device to be used to contrast the contrast of this multiframe picture to obtain best focusing position realization focusing.
A kind of focusing method is applicable to the focusing system that adopts charge-coupled device, and this focusing method comprises the steps:
Travel through a plurality of focusing positions, adopt default time for exposure that photographed scene is exposed to obtain multiframe picture that should a plurality of focusing positions at each focusing position, this photographed scene is in the luminous environment that the power supply of predetermined period produces, it should be n/2 times of this predetermined period and default time for exposure less than the vertical sync period of this charge-coupled device, wherein, n is a natural number; And
The contrast that contrasts this multiframe picture realizes focusing to obtain best focusing position.
Because the n/2 that should the default time for exposure be this predetermined period doubly, and the brightness period of change of the luminous environment that the power supply of this predetermined period produces is 1/2 of this predetermined period, so, this focusing system is carried out this focusing method and is adopted the brightness value of the multiframe picture that this default time for exposure exposure obtains always identical at a plurality of focusing positions, the contrast of multiframe picture changes with the Changing Pattern of focusing position, can obtain best focusing position by the contrast of contrast multiframe picture, realize correctly focusing.
Description of drawings
Fig. 1 is the high-level schematic functional block diagram of the focusing system of preferred embodiment;
Fig. 2 is the hardware connection diagram of focusing system shown in Figure 1;
Fig. 3 is the flow chart of the focusing method of preferred embodiment;
Fig. 4 is a kind of sequential schematic diagram of the focusing method of preferred embodiment;
Fig. 5 is a kind of brightness and the contrast response curve schematic diagram that the focusing method of preferred embodiment obtains;
Fig. 6 is that traditional focusing system is carried out a kind of sequential schematic diagram that traditional focusing method obtains in the luminous environment of 50 hertz of power supplys generations; And
Fig. 7 is that traditional focusing system is carried out a kind of brightness and the contrast response curve schematic diagram that traditional focusing method obtains in the luminous environment of 50 hertz of power supplys generations.
Embodiment
See also Fig. 1, the focusing system 100 of preferred embodiment comprises camera lens 10, CCD20, actuator 30, exposure control unit 40 and asks burnt device 50.Camera lens 10 is used for the photographed scene optical imagery, and photographed scene is in the luminous environment that the power supply of predetermined period produces.CCD20 is used for the image optics signal of sensing camera lens 10 and is converted into the picture of electrical signal form.Actuator 30 is used to drive a plurality of focusing positions of camera lens 10 traversals.Exposure control unit 40 is used to control CCD20 and adopts the default time for exposure to realize electronic shutter function at each focusing position, to obtain the multiframe picture of corresponding a plurality of focusing positions.The default time for exposure be predetermined period n/2 doubly and less than the vertical sync period of CCD20, wherein, n is a natural number.Ask burnt device 50 to be used to contrast the contrast of multiframe picture to obtain the most burnt focusing position realization focusing.
See also Fig. 2, particularly, camera lens 10 comprises drive rail 11 and is located at two on the drive rail 11 and forms as eyeglass 12.CCD20 is arranged at camera lens 10 picture sides.Actuator 30 adopts rotary step motor, and the rotating shaft of rotary step motor is connected with drive rail 11 to drive drive rail 11 drive imaging eyeglasses 12 moves on drive rail 11.Rotary step motor cooperates with drive rail 11 makes imaging eyeglass 12 have a plurality of focusing position P in focusing range L
1~ P
k
Certainly, the setting of camera lens 10 and actuator 30 is not limited to present embodiment, can adopt other setting.As, the more imaging eyeglass of number is set to improve the image quality of camera lens 10, adopt linear step motor replacement drive rail 11 and rotary step motor or employing voice coil motor and supporting guide rail to replace rotary step motor and drive rail 11.
Exposure control unit 40 and asking be built in the burnt device 50 micro controller 61 (Micro Controller Unit, MCU) in, MCU61 is arranged at the CCD20 rear end.MCU61 adopts intelligent chip, can carry out read, function such as calculating, signal output.
Certainly, exposure control unit 40 and ask the setting of burnt device 50 to be not limited to present embodiment, exposure control unit 40 and ask burnt device 50 to be built in the special intelligent chip in can be respectively.
See also Fig. 3, the focusing method of preferred embodiment comprises the steps:
S01: travel through a plurality of focusing positions, adopt default time for exposure that photographed scene is exposed to obtain multiframe picture that should a plurality of focusing positions at each focusing position, photographed scene is in the luminous environment that the power supply of predetermined period produces, the default time for exposure is that the n/2 of predetermined period is doubly and less than the vertical sync period of CCD20, wherein, n is a natural number; And
S02: the contrast that contrasts this multiframe picture realizes focusing to obtain best focusing position.
See also Fig. 4, as example, photographed scene is in the luminous environment that the power supply of 50 hertz (being that predetermined period is 20ms) produces.Reference axis 62 is time shaft (t), and curve 63 characterizes the brightness variation characteristic of luminous environment, that is, the brightness of luminous environment is on the occasion of the trigonometric function variation, and the cycle is 10ms (i.e. 1/2 predetermined period).The vertical sync period of CCD20 is 33.33ms.P
1~ P
kA plurality of focusing positions for digital camera.
Particularly, for step S01, actuator 30 is driven into picture eyeglass 12 and travels through a plurality of focusing position P on drive rail 11
1~ P
kOn each focusing position, exposure control unit 40 control CCD20 adopt the default time for exposure to expose, and exposure betides the rear (promptly less than CCD20 vertical sync period) of a vertical sync period of CCD20.In the present embodiment, the default time for exposure is 10ms, and is identical with the brightness period of change of luminous environment.Know by the signal sampling principle, so be set, the brightness L of the multiframe picture that multiexposure, multiple exposure obtains the default time for exposure
1~ L
kIdentical.
See also Fig. 5, for focusing system 100 is carried out a kind of brightness and the contrast response curve schematic diagram that the focusing method of preferred embodiment obtains in the luminous environment that 50 hertz power supply produces.Reference axis 64 is expressed as picture eyeglass 12 residing focusing position P
1~ P
k, reference axis 65 characterizes the contrast of picture, and reference axis 66 characterizes the brightness of picture, and curve 67 is the luminosity response of picture, and curve 68 is the contrast response curve of picture.Because the brightness L of multiframe picture
1~ L
kIdentical, so curve 67 near linears.And the contrast C of multiframe picture
1~ C
kChanging Pattern with focusing position changes, and curve 68 has a peak value.
So, for step S02, ask burnt device 50 can pass through the contrast C of contrast multiframe picture
1~ C
kAccurately determine the most burnt focusing position.Particularly, the focusing position that the picture of contrast maximum (imaging is the most clear) is corresponding is best focusing position, the focusing position of promptly the most contiguous curve 68 peak value correspondences.Particularly, ask burnt device 50 to determine best focusing positions after, actuator 30 is driven into picture eyeglass 12 to best focusing position and realizes focusing.
The default time for exposure that is appreciated that present embodiment can also be made as 20ms and 30ms, decides according to the bright-dark degree of luminous environment.As, if focus in dark situation, the then default time for exposure is made as 30ms, if focus in the bright ring border, the then default time for exposure is made as 10ms.So preferably, the focusing method of preferred embodiment is preceding in traversal and step of exposure (step S01), also comprises step:
S00: selected default time for exposure.
For step S00, can select (promptly selected n value, present embodiment can be selected and preset the time for exposure is 10ms, 20ms or 30ms) according to the bright-dark degree of luminous environment by the user.As, focusing system 100 includes user interface (figure does not show), and user interface is connected with MCU61, and the user can preset the time for exposure by user interface is selected, and reads in the exposure control unit 40 of MCU61, thereby realizes presetting the selected of time for exposure.
Certainly, step S00 is not limited to present embodiment (being finished by the user), and an alternative scheme is: focusing system 100 possesses the function of selected default time for exposure automatically.As, focusing system 100 also includes and luminance assessor (figure does not show), luminance assessor (as, light-sensitive element or the signal processing apparatus that is connected with CCD20) be used to evaluate the bright-dark degree of luminous environment and feed back to MCU61, MCU61 is according to the selected default time for exposure of the luminous environment bright-dark degree of luminance assessor evaluation, thereby realization 100 pairs of default time for exposure of focusing system is selected automatically.
Be appreciated that the then default time for exposure should correspondingly be provided with if focusing system 100 is used for other luminous environments (being the luminous environment of the power supply generation of other frequencies).
As from the foregoing, because the default time for exposure is made as n/2 times of predetermined period, and the brightness period of change of the luminous environment that the power supply of predetermined period produces is 1/2 of a predetermined period, so, focusing system of the present invention is carried out focusing method of the present invention and is adopted the brightness value of the multiframe picture that default time for exposure exposure obtains always identical at a plurality of focusing positions, the contrast of multiframe picture changes with the Changing Pattern of focusing position, can obtain best focusing position by the contrast of contrast multiframe picture, realize correctly focusing.
Be noted that the foregoing description only is better embodiment of the present invention, those skilled in the art also can do other variation in spirit of the present invention.The variation that these are done according to spirit of the present invention all should be included within the present invention's scope required for protection.
Claims (10)
1. a focusing system is characterized in that, this focusing system comprises:
Camera lens is used for the photographed scene optical imagery, and this photographed scene is in the luminous environment that the power supply of predetermined period produces;
Charge-coupled device is used for the imaging signal of this camera lens of sensing and is converted into the picture of electrical signal form;
Actuator is used to drive this camera lens and travels through a plurality of focusing positions;
Exposure control unit, being used to control this charge-coupled device adopts the default time for exposure to realize electronic shutter function at each focusing position, to obtain to multiframe picture that should a plurality of focusing positions, it should be n/2 times of this predetermined period and default time for exposure less than the vertical sync period of this charge-coupled device, wherein, n is a natural number; And
Ask burnt device, be used to contrast the contrast of this multiframe picture to obtain best focusing position realization focusing.
2. focusing system as claimed in claim 1 is characterized in that, this scheduled exposure time is 10 milliseconds, 20 milliseconds or 30 milliseconds.
3. focusing system as claimed in claim 1 is characterized in that this scheduled exposure time is less than 33.33 milliseconds.
4. focusing system as claimed in claim 1 is characterized in that this scheduled exposure time is by user's chosen in advance.
5. focusing system as claimed in claim 1 is characterized in that, this scheduled exposure time is selected automatically by this focusing system.
6. focusing method is used to adopt the focusing system of charge-coupled device, and this focusing method comprises the steps:
Travel through a plurality of focusing positions, adopt default time for exposure that photographed scene is exposed to obtain multiframe picture that should a plurality of focusing positions at each focusing position, this photographed scene is in the luminous environment that the power supply of predetermined period produces, it should be n/2 times of this predetermined period and default time for exposure less than the vertical sync period of this charge-coupled device, wherein, n is a natural number; And
The contrast that contrasts this multiframe picture realizes focusing to obtain best focusing position.
7. focusing method as claimed in claim 6 is characterized in that, this scheduled exposure time is 10 milliseconds, 20 milliseconds or 30 milliseconds.
8. focusing method as claimed in claim 6 is characterized in that this scheduled exposure time is less than 33.33 milliseconds.
9. focusing method as claimed in claim 6 is characterized in that, this focusing method also comprises step before this traversal and step of exposure:
The selected default time for exposure.
10. focusing method as claimed in claim 9 is characterized in that, this selected step is finished by user or this focusing system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007102012677A CN101360188A (en) | 2007-08-03 | 2007-08-03 | Focusing system and focusing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007102012677A CN101360188A (en) | 2007-08-03 | 2007-08-03 | Focusing system and focusing method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101360188A true CN101360188A (en) | 2009-02-04 |
Family
ID=40332514
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2007102012677A Pending CN101360188A (en) | 2007-08-03 | 2007-08-03 | Focusing system and focusing method |
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|---|---|
| CN (1) | CN101360188A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104954680A (en) * | 2015-06-16 | 2015-09-30 | 深圳市金立通信设备有限公司 | Camera focusing method and terminal |
| CN112202374A (en) * | 2020-09-28 | 2021-01-08 | 广东工业大学 | Voice coil motor micro-positioning platform, motion control method, device and system |
| US11775143B2 (en) | 2007-01-08 | 2023-10-03 | Samsung Electronics Co., Ltd. | Method and apparatus for providing recommendations to a user of a cloud computing service |
-
2007
- 2007-08-03 CN CNA2007102012677A patent/CN101360188A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11775143B2 (en) | 2007-01-08 | 2023-10-03 | Samsung Electronics Co., Ltd. | Method and apparatus for providing recommendations to a user of a cloud computing service |
| CN104954680A (en) * | 2015-06-16 | 2015-09-30 | 深圳市金立通信设备有限公司 | Camera focusing method and terminal |
| CN112202374A (en) * | 2020-09-28 | 2021-01-08 | 广东工业大学 | Voice coil motor micro-positioning platform, motion control method, device and system |
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Open date: 20090204 |