CN101924859B

CN101924859B - Method for acquiring monochrome data of complementary metal-oxide-semiconductor (CMOS) image sensor

Info

Publication number: CN101924859B
Application number: CN2010102478503A
Authority: CN
Inventors: 黄权; 钱志恒; 马震伟; 杨波
Original assignee: HANGZHOU SHENGYUAN CHIP TECHNIQUE CO Ltd
Current assignee: HANGZHOU SYNODATA SECURITY TECHNOLOGY CO., LTD.
Priority date: 2010-08-05
Filing date: 2010-08-05
Publication date: 2012-07-18
Anticipated expiration: 2030-08-05
Also published as: CN101924859A

Abstract

The invention relates to a method for acquiring monochrome data of a complementary metal-oxide-semiconductor (CMOS) image sensor. The method comprises the following steps of: halving frequencies of a line synchronizing signal and a pixel synchronizing signal which are output by the CMOS image sensor with a frequency halving machine; and then accessing the signals into a host processor. The method has the advantages of accessing the signals into the host processor after halving the frequencies of the line synchronizing signal and the pixel synchronizing signal which are output by the CMOS image sensor, not needing to reprocess the acquired data after acquisition and contributing to acquiring the monochrome data. Data processed by the host processor is only one quarter of all the data.

Description

A kind of acquisition method of cmos image sensor monochromatic data

Technical field

The present invention relates to the IMAQ field, especially a kind of acquisition method of cmos image sensor monochromatic data.

Background technology

The basic means that cmos image sensor adopts light sensitive diode to catch as image.This diode can produce output current after accepting irradiate light, current's intensity is then corresponding with the intensity of illumination.Cmos image sensor also comprises amplifier and analog to digital conversion circuit, receives the current strength of irradiate light generation to be converted into digital signal light sensitive diode and exports.

The color of cmos image sensor: red, green, blue is three primary colors.Color in the nature can be formed by these 3 kinds of blend of colors.Cmos image sensor all has 1 filter before each pixel, only allow red, green or blueness is passed through, and guarantees that like this each pixel only gathers the corresponding color light intensity.Typical C mos image sensor pixel collection light color is arranged as shown in Figure 1, and G representes green among the figure, and R representes redness, and B representes blueness; It is thus clear that: red, blue pixel respectively account for total pixel 1/4, green pixel accounts for 1/2 of total pixel.

The cmos image sensor output format: typical C mos image sensor output format is as shown in Figure 2 down: frame synchronizing signal=0 expression has view data output; Line synchronizing signal=1 expression has view data output; The typical case can acquisition of image data at the pixel synchronizing signal rising edge, and data are the cmos image sensor dateout.

In some application, only need to gather monochromatic image data.For example in the fingerprint collecting field, or only need to gather red blue such monochromatic image data.Gather in the circuit of cmos image sensor at present, as shown in Figure 3, frame synchronizing signal, line synchronizing signal, pixel synchronizing signal directly connect processor.Workflow is as shown in Figure 4, and processor captures frame synchronizing signal through interrupting or poll, through interrupting or poll, captures line synchronizing signal then, then according to pixel synchronizing signal, gathers the data that cmos image sensor sends.According to the cmos image sensor output format, take out the monochromatic data that wherein needs at last.

Though monochromatic image data only accounts for 1/4 of total data, existing method also need collect all images data.So just cause: the data space that 1) needs is big; 2) each pixel all will be handled, and takies a large amount of processing times of processor.

Summary of the invention

When the objective of the invention is solve to gather in the cmos image sensor monochrome information, also must gather entire image, cause that to take data space big, take many problems of primary processor time, and a kind of acquisition method of cmos image sensor monochromatic data is provided.

The present invention solves the technical scheme that its technical problem adopts: the acquisition method of this cmos image sensor monochromatic data, line synchronizing signal and pixel synchronizing signal that cmos image sensor is exported pass through the two-divider two divided-frequency, and then insert primary processor.

The effect that the present invention is useful is: with inserting primary processor again behind the line synchronizing signal of cmos image sensor output, the pixel synchronizing signal two divided-frequency; Need the data that collect not dealt with in addition again after gathering completion yet; Make things convenient for monochrome image according to collection, and the data that primary processor need be handled have only 1/4 of total data.

Description of drawings

Fig. 1 is a cmos image sensor pixel color distribution map in the prior art;

Fig. 2 is a typical cmos image sensor output timing diagram in the prior art;

Fig. 3 is existing cmos image sensor acquisition system block diagram;

Fig. 4 is existing cmos image sensor acquisition system workflow diagram;

Fig. 5 is a two divided-frequency line synchronizing signal pixel synchronizing signal sequential chart among the present invention.

Fig. 6 is a cmos image sensor acquisition system block diagram of the present invention;

Fig. 7 is a cmos image sensor acquisition system flow chart of the present invention;

Fig. 8 is a two-divider circuit diagram of the present invention;

Fig. 9 is a two-divider circuit timing diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is described further:

Because monochrome signal just is interlacing, exports at a distance from row, the present invention is with the line synchronizing signal and the pixel synchronizing signal two divided-frequency of cmos image sensor output, and then the access primary processor, and is as shown in Figure 6.Like this, the data that need handle of primary processor have only 1/4 of total data.

As shown in Figure 5, the high expression of line synchronizing signal has data output among the figure, at this moment at the synchronous rising edge of pixel, export blue, green, blue, green, After line output finishes, the line synchronizing signal step-down.When line synchronizing signal uprises next time, output next line data: green, red, green, red, green, red ..., after the two divided-frequency line synchronizing signal, former 2 line outputs become 1 line output.Behind the two divided-frequency pixel synchronizing signal, former 2 pixels output becomes 1 pixel output, so output becomes: blue, blue, blue, blue ... Promptly reach and only gather blue effect.

Improved cmos image sensor acquisition system flow chart is as shown in Figure 7, compares with former cmos image sensor acquisition system flow process, owing to used two-divider directly line synchronizing signal, pixel synchronizing signal to be carried out two divided-frequency.Directly collected monochromatic data when gathering like this.Need the data that collect not dealt with in addition again after gathering completion yet.

Fig. 8 is a frequency-halving circuit instance, an actual two-divider circuit diagram of realizing; 74HC74 is the d type flip flop that rising edge triggers.

is the zero clearing input;

is for being provided with input; CP is an input clock; D is for triggering input; Q is for the output clock, and

is the negate of output clock.In the circuit; Power supply meets 3.3V, and

directly meets 3.3V. connects primary processor, controlled by primary processor.CP connects input clock, i.e. line synchronizing signal, perhaps pixel synchronizing signal.

directly links to each other with D.Q is the two divided-frequency signal of output.

Following table is the 74HC74 truth table:

Annotate:

H=high level (stable state)

L=low level (stable state)

X=ignores

The T=rising edge

The level state of QO=Q before initial conditions is set up

Fig. 9 is a two-divider circuit timing diagram of the present invention, the analysis circuit course of work:

1, initial condition;

is L; According to truth table: Q=L; links to each other with D owing to , so D also is H

2, CP rising edge; D is H; According to truth table: Q=H,

D becomes L

3, CP=L; According to truth table: Q=H,

D=L

4, CP rising edge; D=L; According to truth table: Q=L, D becomes H

5, CP=L; According to truth table: Q=L,

D=H

6, CP rising edge; D is H; According to truth table: Q=H,

D becomes L

Every like this CP input 2 pulses, Q export 1 pulse, have realized 2 frequency dividing circuit functions.

Terminological interpretation

Imageing sensor: can experience optical image information and convert the transducer of usable output signal to.

Cmos image sensor: the imageing sensor that adopts CMOS (Complementary Metal-Oxide Semiconductor, metal oxide semiconductor device).

Frame a: sub-picture of imageing sensor output.Every frame is made up of several rows.

OK: delegation's image of imageing sensor output.Every row is made up of some pixels.

Pixel: the unit of the minimum of imageing sensor output image, the data of 1 sampled point of expression.

Frame synchronizing signal: cmos image sensor output signal, represent that a new frame begins.

Line synchronizing signal: cmos image sensor output signal, represent that new delegation begins.

Pixel synchronizing signal: cmos image sensor output signal, the expression output image data is effective.

Frequency division: a clock signal is transformed into clock signals of different frequencies output through certain circuit structure.

Two divided-frequency: output signal frequency is 1/2nd of a frequency input signal.Be 2 pulse signals of every input, export 1 pulse signal.

Except that the foregoing description, the present invention can also have other execution modes.All employings are equal to the technical scheme of replacement or equivalent transformation formation, all drop on the protection range of requirement of the present invention.

Claims

1. the acquisition method of a cmos image sensor monochromatic data is characterized in that: the line synchronizing signal and the pixel synchronizing signal of cmos image sensor output are passed through the two-divider two divided-frequency, and then insert primary processor; The high expression of line synchronizing signal has data output, at this moment at the synchronous rising edge of pixel, export blue, green, blue, green ..., after line output finishes, the line synchronizing signal step-down; When line synchronizing signal uprises next time, output next line data: green, red, green, red, green, red After the two divided-frequency line synchronizing signal, former 2 line outputs become 1 line output; Behind the two divided-frequency pixel synchronizing signal, former 2 pixels output becomes 1 pixel output, and output becomes: blue, blue, blue, blue ..., promptly reach and only gather blue purpose.