CN2639926Y - Digital camera autoamtic exposure circuit - Google Patents
Digital camera autoamtic exposure circuit Download PDFInfo
- Publication number
- CN2639926Y CN2639926Y CN03256165.2U CN03256165U CN2639926Y CN 2639926 Y CN2639926 Y CN 2639926Y CN 03256165 U CN03256165 U CN 03256165U CN 2639926 Y CN2639926 Y CN 2639926Y
- Authority
- CN
- China
- Prior art keywords
- brightness
- comparer
- circuit
- exposure
- selector switch
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Transforming Light Signals Into Electric Signals (AREA)
Abstract
The utility model discloses an automatic exposure circuit for digital cameras, comprising a brightness detector and an improved exposure time calculating circuit. The average brightness got after the brightness detecting is input into the exposure time calculating circuit, which comprises a brightness comparator, an exposure adder with an auxiliary circuit, an error adder with an auxiliary circuit and an iterative step calculating circuit; wherein, the average brightness, the upper and the lower brightness limits are compared with each other in the brightness comparator, getting the control signals representing over-exposure and under-exposure; the output of the brightness comparator is input into the error adder and the auxiliary circuit to calculate the errors between the average brightness and the upper and the lower brightness limits, and then is input into the iterative step calculating circuit to get the prior iterative step; on the other hand the output of the brightness comparator is also input into the exposure adder and the auxiliary circuit to get and output a new exposure time. The utility model can not only guarantee the operation precision of the exposure time, but also greatly improve the lock time of the exposure time, thereby is suitable for various illuminance.
Description
Affiliated technical field
The utility model relates to the digital camera automatic exposure circuit, relates in particular to a kind of being applied in and adopts charge-coupled device (CCD) to carry out automatic exposure circuit on the digital camera of image acquisition.
Background technology
In digital camera, under the condition of given illumination, can determine the time shutter, thereby realize automatic exposure according to the variation of shutter speed and brightness of image.And under the situation of fixing shutter speed, only just can determine the correct time shutter according to the variation of brightness of image.In the ordinary course of things, can represent the brightness of entire image with the mean flow rate of image all or part pixel.
General time shutter counting circuit all adopts fixing time shutter iteration step length, this just causes following two kinds of situations easily: if iteration step length is excessive, then iteration speed is very fast, but when arriving the exposure control area, be difficult for convergence (possible iteration step length specific luminance control area is big), thereby influence iteration precision, be difficult to determine the time shutter; And if iteration step length is too small, can influence iteration speed again, need the long period to determine the time shutter.
Summary of the invention
At the problems referred to above, the utility model provides a kind of digital camera automatic exposure circuit that improves the time shutter counting circuit, in carrying out the time shutter calculation process, adopt adaptive variable exposure time iteration step-length, thereby when guaranteeing operational precision, reach the quick lock in of time shutter, and be suitable for various illumination situations.
The technical solution of the utility model is: a kind of digital camera automatic exposure circuit comprises brightness detector and improved time shutter counting circuit.Detect the mean flow rate that obtains afterwards through brightness and send into the time shutter counting circuit.Described time shutter counting circuit comprises brightness comparer, exposure totalizer and auxiliary circuit, error totalizer and auxiliary circuit thereof, iteration step length counting circuit.Mean flow rate and brightness upper and lower limit compare at the brightness comparer, obtain characterizing over-exposed and under-exposed control signal.Error totalizer and auxiliary circuit thereof are sent in the output of brightness comparer on the one hand, calculate the error between mean flow rate and the brightness upper and lower limit, send into the iteration step length counting circuit, calculate current iteration step length; Send into exposure totalizer and auxiliary circuit thereof on the other hand, add or deduct an iteration step length, obtain new time shutter and output in the current time shutter.
In the utility model, the time shutter iteration step length calculates according to luminance errors and current time shutter.According to the size of luminance errors, the decision iteration step length accounts for the ratio of current time shutter, and error greatly then ratio is big, and the little then ratio of error is little, thereby realizes adaptive variable iteration step length.Like this, iteration step length is also bigger when luminance errors is bigger, has improved iteration speed; And iteration step length is also less when luminance errors is less, has improved iteration precision.Iteration step length and current time shutter are connected, further guaranteed the convergence of iteration.
Than prior art, the utility model can guarantee the operational precision of time shutter, can improve the time shutter time of locking greatly again, and is fit to various illumination situation.
Description of drawings
Fig. 1 is the time shutter of digital camera and the graph of a relation between the brightness of image;
Fig. 2 is the block diagram of general digital camera automatic exposure circuit;
Fig. 3 is the block diagram of the time shutter counting circuit of general digital camera automatic exposure circuit;
Fig. 4 is the block diagram of the time shutter counting circuit that provides of the utility model digital camera automatic exposure circuit;
Fig. 5 is the block diagram of the time shutter iteration step length counting circuit that provides of the utility model;
Fig. 6 is the process flow diagram of the time shutter counting circuit that provides of the utility model.
Embodiment
Below in conjunction with the drawings and specific embodiments the utility model is described in further detail.
Fig. 1 is the time shutter of digital camera and the graph of a relation between the brightness of image.Under the situation of fixing shutter speed, brightness of image and retention wire sexual intercourse between the time shutter.Under certain illumination, the brightness of image control area of correct exposure is corresponding to certain exposure control area, and under different illumination, its exposure control area is different.Therefore, can preestablish the brilliance control zone, when mean flow rate enters brilliance control when zone, think that then the time shutter entered corresponding exposure control area, thereby realize correct exposure.
Fig. 2 is the block diagram of general digital camera automatic exposure circuit, comprises brightness detector and time shutter counting circuit.Image brightness signal detects through brightness, obtains mean flow rate, sends into the time shutter counting circuit, calculates the time shutter of more approaching exposure control area.Microprocessor is responsible for the new time shutter is write the timing generator circuit of imageing sensor, changes exposure time series, thereby realizes automatic exposure.Above process need iteration repeatedly finally obtains the correct time shutter.
Fig. 3 is the time shutter counting circuit that general digital camera automatic exposure circuit is adopted.The mean flow rate of image and brightness upper and lower limit compare, and are over-exposed or under-exposure with the decision present image.If mean flow rate is then over-exposed greater than the brightness upper limit, should deduct a time shutter iteration step length from the current time shutter, as new time shutter output; If mean flow rate is then under-exposed less than the brightness lower limit, should add a time shutter iteration step length in the current time shutter, as new time shutter output.If mean flow rate is between the brightness upper and lower limit, then exposure is correct, stops iteration.
Fig. 4 has provided a time shutter counting circuit described in the utility model.
Among Fig. 4, the time shutter counting circuit comprises brightness comparer 30 and brightness comparer 31, exposure totalizer 35, exposure totalizer auxiliary circuit, error totalizer 45, error totalizer auxiliary circuit and iteration step length counting circuit F1.The mean flow rate and the brightness upper limit compare at brightness comparer 30, and it is over-exposed to equal 1 representative; Compare at brightness comparer 31 with the brightness lower limit, equal 1 and represent under-exposure.Error totalizer auxiliary circuit comprises phase inverter 40, selector switch 41, phase inverter 42, selector switch 43 and selector switch 44.The paraphase (negative value) of over-exposed signal controlling selector switch 41 output mean flow rates or mean flow rate, the paraphase (negative value) of over-exposed signal and under-exposed signal controlling selector switch 43 and the 44 output brightness upper limits or brightness lower limit, computing is carried out in selector switch 41 and 44 output in error totalizer 45, thereby obtain between the brightness upper limit and the mean flow rate or mean flow rate and brightness lower limit between difference, i.e. luminance errors.Luminance errors and current time shutter are admitted to iteration step length counting circuit F1, through calculating current time shutter iteration length, send into exposure totalizer 35 and auxiliary circuit thereof.Exposure totalizer auxiliary circuit comprises phase inverter 32, selector switch 33 and 34, under the control of over-exposed signal and under-exposed signal, output iteration step length or its paraphase (negative value) with current time shutter addition, obtain new time shutter and output to exposure totalizer 35.
Fig. 5 has provided an iteration step length counting circuit described in the utility model.
Among Fig. 5, the iteration step length counting circuit comprises comparer 50, comparer 51, comparer 52, comparer 53, comparer 54, selector switch 55, selector switch 56, selector switch 57, selector switch 58, selector switch 59, shift register 60.Δ
1～Δ
5Be one group of value of progressively successively decreasing, can be divided into 6 intervals, λ 0～255
1～λ
6Be one group of value that progressively increases progressively, represent the displacement length of shift register 60, corresponding one by one with 6 intervals.Luminance errors and Δ
1～Δ
5In comparer 50, comparer 51, comparer 52, comparer 53 and comparer 54, compare one by one, thus the interval at decision luminance errors place, and control selector switch 55, selector switch 56, selector switch 57, selector switch 58, selector switch 59 output λ
1～λ
6One of them, i.e. the displacement length of luminance errors correspondence.The current time shutter moves to right in shift register 60 after this length, obtains iteration step length.
For example, get Δ
1～Δ
5Be respectively 128,64,32,16,8, get λ again
1～λ
6Be respectively 1,2,3,4,5,6, luminance errors delta adopts 8 bits to represent, is 0～255 therefore.The iteration length lambda and the current time shutter E that calculate of foregoing circuit then
cRelation as follows:
If delta is positioned between (128,255), lambda=(1/2) E then
c
If delta is positioned between (64,127), lambda=(1/4) E then
c
If delta is positioned between (32,63), lambda=(1/8) E then
c
If delta is positioned between (16,31), lambda=(1/16) E then
c
If delta is positioned between (8,15), lambda=(1/32) E then
c
If delta is positioned between (0,7), lambda=(1/64) E then
c
After the new time shutter obtains, be written to the timing generator circuit of image processor (CCD) by microprocessor.Above process just can be locked in the time shutter control area through after some these iteration, thereby realizes automatic exposure.
Claims (2)
1, a kind of digital camera automatic exposure circuit comprises brightness detector and time shutter counting circuit; Detect the mean flow rate that obtains afterwards through brightness and send into the time shutter counting circuit, it is characterized in that: described time shutter counting circuit comprises brightness comparer, exposure totalizer and auxiliary circuit, error totalizer (45) and auxiliary circuit thereof, iteration step length counting circuit; Mean flow rate and brightness upper and lower limit compare at the brightness comparer, obtain characterizing over-exposed and under-exposed control signal; Error totalizer and auxiliary circuit thereof are sent in the output of brightness comparer on the one hand, calculate the error between mean flow rate and the brightness upper and lower limit, send into the iteration step length counting circuit, calculate current iteration step length; Send into exposure totalizer and auxiliary circuit thereof on the other hand, add or deduct an iteration step length, obtain new time shutter and output in the current time shutter.
2. a kind of digital camera automatic exposure circuit according to claim 1 is characterized in that the auxiliary circuit of described error totalizer (45) comprises phase inverter (40), selector switch (41), phase inverter (42), selector switch (43) and selector switch (44); Described iteration step length counting circuit comprises comparer, selector switch, shift register (60); Described comparer comprises comparer (50), comparer (51), comparer (52), comparer (53), comparer (54), and described selector switch comprises selector switch (55), selector switch (56), selector switch (57), selector switch (58), selector switch (59).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN03256165.2U CN2639926Y (en) | 2003-07-31 | 2003-07-31 | Digital camera autoamtic exposure circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN03256165.2U CN2639926Y (en) | 2003-07-31 | 2003-07-31 | Digital camera autoamtic exposure circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2639926Y true CN2639926Y (en) | 2004-09-08 |
Family
ID=34295317
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN03256165.2U Expired - Fee Related CN2639926Y (en) | 2003-07-31 | 2003-07-31 | Digital camera autoamtic exposure circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2639926Y (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100389362C (en) * | 2005-04-04 | 2008-05-21 | 北京中星微电子有限公司 | Exposure regulating method and device |
| CN104301619A (en) * | 2014-02-24 | 2015-01-21 | 凯迈（洛阳）测控有限公司 | Fast camera exposure time automatic adjusting method and device |
| CN107172353A (en) * | 2017-06-16 | 2017-09-15 | 广东欧珀移动通信有限公司 | Automatic explosion method, device and computer equipment |
| CN107241559A (en) * | 2017-06-16 | 2017-10-10 | 广东欧珀移动通信有限公司 | Portrait photographic method, device and picture pick-up device |
| CN108668127A (en) * | 2018-08-01 | 2018-10-16 | 昆山丘钛微电子科技有限公司 | Imaging device time for exposure test device |
| CN112203021A (en) * | 2020-09-30 | 2021-01-08 | 歌尔科技有限公司 | Brightness control parameter adjusting method and device, electronic equipment and readable storage medium |
| CN112261310A (en) * | 2020-10-23 | 2021-01-22 | 天津市气象信息中心(天津市气象档案馆) | Automatic adjusting method for observation brightness of digital visibility meter |
| CN112312036A (en) * | 2020-10-30 | 2021-02-02 | 天津天地伟业智能安全防范科技有限公司 | Automatic exposure method in photographing field |
-
2003
- 2003-07-31 CN CN03256165.2U patent/CN2639926Y/en not_active Expired - Fee Related
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100389362C (en) * | 2005-04-04 | 2008-05-21 | 北京中星微电子有限公司 | Exposure regulating method and device |
| CN104301619B (en) * | 2014-02-24 | 2018-01-26 | 凯迈（洛阳）测控有限公司 | A kind of quickly camera exposure time automatic adjusting method and device |
| CN104301619A (en) * | 2014-02-24 | 2015-01-21 | 凯迈（洛阳）测控有限公司 | Fast camera exposure time automatic adjusting method and device |
| CN107172353B (en) * | 2017-06-16 | 2019-08-20 | Oppo广东移动通信有限公司 | Automatic explosion method, device and computer equipment |
| CN107241559A (en) * | 2017-06-16 | 2017-10-10 | 广东欧珀移动通信有限公司 | Portrait photographic method, device and picture pick-up device |
| CN107172353A (en) * | 2017-06-16 | 2017-09-15 | 广东欧珀移动通信有限公司 | Automatic explosion method, device and computer equipment |
| CN107241559B (en) * | 2017-06-16 | 2020-01-10 | Oppo广东移动通信有限公司 | Portrait photographing method and device and camera equipment |
| CN108668127A (en) * | 2018-08-01 | 2018-10-16 | 昆山丘钛微电子科技有限公司 | Imaging device time for exposure test device |
| CN108668127B (en) * | 2018-08-01 | 2019-09-27 | 昆山丘钛微电子科技有限公司 | Imaging device time for exposure test device |
| CN112203021A (en) * | 2020-09-30 | 2021-01-08 | 歌尔科技有限公司 | Brightness control parameter adjusting method and device, electronic equipment and readable storage medium |
| CN112203021B (en) * | 2020-09-30 | 2022-04-15 | 歌尔科技有限公司 | Brightness control parameter adjusting method and device, electronic equipment and readable storage medium |
| CN112261310A (en) * | 2020-10-23 | 2021-01-22 | 天津市气象信息中心(天津市气象档案馆) | Automatic adjusting method for observation brightness of digital visibility meter |
| CN112312036A (en) * | 2020-10-30 | 2021-02-02 | 天津天地伟业智能安全防范科技有限公司 | Automatic exposure method in photographing field |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN2639926Y (en) | Digital camera autoamtic exposure circuit | |
| GB2219461A (en) | Exposure control device | |
| JPH04273777A (en) | Exposure control circuit | |
| US5512947A (en) | Video camera | |
| CN1829290A (en) | Mobile communications terminal for compensating automatic exposure of camera and method thereof | |
| JPS62236273A (en) | Black level correcting circuit for video camera | |
| CN1604619A (en) | Black level correction circuit and method for imaging apparatus using solid imaging element | |
| EP0924544A2 (en) | Auto-focusing apparatus and method | |
| CN1114820C (en) | Light measuring method | |
| CN1512256A (en) | Automatic exposure sampling and control method for image shooting device | |
| CN1281067C (en) | Automatic flash lamp device and automatic flash method for digital camera | |
| JP3105523B2 (en) | Electronic imaging device | |
| CN1177121A (en) | Iris control apparatus for video camera | |
| JPH0396931A (en) | Image blurring preventing device | |
| JP4314898B2 (en) | Imaging apparatus and image control method thereof | |
| US20050275745A1 (en) | Quick focusing method for a digital camera | |
| JPH05122600A (en) | Exposure controller for video camera | |
| JP2004334042A (en) | Exposure control method and device for camera type vehicle sensor | |
| JP3510286B2 (en) | Automatic tracking device | |
| JP3449489B2 (en) | Tracking device | |
| KR20210128202A (en) | Camera recognition vehicle access control system | |
| JP4167469B2 (en) | Motion vector detection device | |
| JP2675807B2 (en) | Imaging device | |
| CN202551196U (en) | Network camera automatic light supplementing circuit | |
| CN101059714A (en) | Computer system for prosecuting corresponding operation according to scene change and its method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |