TWI427508B - An optical sensing device and a method of adjusting an exposure condition for the same - Google Patents

Description

Method for adjusting exposure condition of optical sensing module and optical sensing module thereof

The invention relates to a method for adjusting an exposure condition and an optical sensing module thereof, in particular to a method for adjusting an exposure condition of an optical sensing module and an optical sensing module using the same.

In today's daily life, image capture devices have been widely used in everyday life. After the image capturing device captures the image by using the light sensor and converts it into a digital signal, the digital signals can be stored. The digital signals captured by the image capture device, combined with the digital image processing technology, can be used to design a variety of applications.

The image capture device can also be used with general pointing devices, such as a mouse. The pointing device emits a surface of light and the image capturing device extracts light reflected from the surface. After proper sampling, the pointing device can obtain images at multiple points in time. The digital processor in the pointing device can compare the images at adjacent time points according to the brightness difference of the pixels in the image to determine the direction and distance of the pointing device.

However, when the pointing device works on different surfaces, the intensity of the reflected light from these different surfaces will also vary depending on the material of the surface. Therefore, the intensity of the reflected light received by the pointing device will also vary. If the reflected light is extracted under the same optical conditions, a phenomenon of uneven brightness may occur, causing the pointing device to deviate when judging the moving direction and the distance.

In view of the above problems, the present invention provides a method of adjusting the exposure conditions of an optical sensing module. The optical sensing module is used for a pointing device. The method includes: (A) receiving a reflected light reflected by a working surface; (B) generating an image signal by irradiating the optical sensing module according to the reflected light, the image signal comprising a plurality of brightness signals and an image quality signal; Setting an exposure condition of the optical sensing module according to part of the brightness signal; (D) repeating steps (B) and (C) to cause the optical sensing module to generate a plurality of image quality signals under different exposure conditions; E) According to the image quality signal under different exposure conditions, set the optimal exposure conditions for the corresponding working surface.

The method further comprises the steps of: (F) performing a motion estimation procedure according to the plurality of image signals to generate a reliability value signal; (G) re-executing the step when the reliability value signal is below a threshold value ( A) to step (E).

The invention further provides an optical sensing module for a pointing device. The pointing device generates a displacement signal by moving relative to a working surface and detecting the relative motion by using the optical sensing module. The optical sensing module includes a plurality of optical sensing units and a processor.

A plurality of optical sensing units are configured to periodically receive the reflected light reflected by the working surface and sequentially generate a plurality of image signals. Each image signal includes a plurality of luminance signals and image quality signals.

The processor is configured to sequentially set an exposure condition of the optical sensing module according to a part of the brightness signal of each image signal, and set an optimal exposure condition corresponding to the working surface according to the image quality signal under different exposure conditions. .

The exposure condition is one of an exposure time and an exposure intensity of the optical sensing module, or is a light intensity of the reflected light.

Through the above processes and devices, the optical sensing module can automatically adjust its exposure conditions, so that the optical sensing module can adapt to different working faces, and reduce the brightness of the light reflected by the working surface, thereby determining the moving direction and The probability of deviation in distance.

The detailed features and advantages of the present invention are described in the following detailed description of the embodiments of the present invention. The related objects and advantages of the present invention will be readily understood by those skilled in the art.

Fig. 1 is a schematic view showing the structure of an image capturing device to which the present invention is applied. The image capturing device to which the present invention is applied may be, but not limited to, the structure shown in FIG. 1.

Referring to FIG. 1 , the optical sensor module 10 can include a light emitting device 12 , a plurality of optical sensing units 14 , a memory 16 , and a processor 18 .

The illuminating device 12 emits light to a working surface, and the illuminating device 12 can be a light emitting diode or a laser illuminating device. After the light is emitted to the working surface and reflected, the reflected light is received by the plurality of optical sensing units 14.

The plurality of optical sensing units 14 receive the reflected light in a fixed period or a non-fixed period. The plurality of optical sensing units 14 may be a Charge-coupled Device (CCD) or a Complementary Metal-Oxide-Semiconductor (CMOS), each of the plurality of optical sensing units 14. Represents a pixel. After receiving the reflected light and performing the analog digital conversion, the plurality of optical sensing units 14 can sequentially generate a plurality of image signals in time. Each image signal contains multiple brightness signals and image quality signals. The luminance signal can be a grayscale value of a plurality of bits or a binarized image signal. The plurality of optical sensing units 14 can change the brightness value of the image signal by adjusting the length of the exposure time or the exposure intensity.

The memory 16 can be used to store a plurality of video signals. The processor 18 can be a microprocessor, a microcontroller, an application-specific integrated circuit (ASIC), or a Field Programmable Gate Array (FPGA). The illumination device 12, the optical sensing unit 14 and the memory 16 are controlled, and can be used to perform the shooting parameter adjustment method proposed by the present invention.

In the present invention, the processor 18 is configured to sequentially set an exposure condition of the optical sensing module 10 according to a brightness signal of a portion of each image signal. The optical sensing module 10 generates a plurality of image signals according to a plurality of different exposure conditions. And from these image signals, according to the image quality signal, the exposure condition of one of the images is selected as the optimal exposure condition.

The features of the device of the present invention are described above, and the detailed steps are as follows.

Please refer to FIG. 2, which is a flowchart of a first embodiment of a method for adjusting exposure conditions of an optical sensor module disclosed in the present invention.

In step S101, the light is emitted from the light-emitting device 12 to a working surface, and the reflected light is received by the plurality of optical sensing units 14 in the optical sensing module 10.

In step S103, after receiving the reflected light, the optical sensing module 10 processes the reflected light to generate an image signal. Each image signal includes a plurality of luminance signals and an image quality signal. The image signal is composed of multiple pixels, and each pixel corresponds to a luminance signal. The image quality signal represents the contrast value of the image signal. The contrast value is defined as the maximum value in the luminance signal (or the group with the largest average value after the pixel grouping) and the minimum value (or the minimum average value after the pixel grouping). Group of) the ratio between each other.

In step S105, the optical sensing unit 14 is divided into a plurality of blocks, that is, the plurality of image signals are divided into a plurality of groups. Each block is preferably a square. The processor 18 calculates the average value of the brightness of each block based on the plurality of divided blocks. The average of the brightness of each block is defined as the arithmetic mean or weighted average of the luminance signals of all the pixels in the block.

In this embodiment, the blocks described above may be arranged in accordance with the size of the brightness values. The processor 18 selects one or more blocks from the blocks, and averages the luminance signals of all the pixels in the selected block to obtain an average value of the luminance signals.

Then, the processor 18 generates a difference signal by comparing the target brightness value with the average value of the brightness signal according to a set target brightness value. The difference signal can be the value obtained by subtracting the target brightness value from the average value of the brightness signal. With the difference signal, the exposure conditions of the optical sensing module 10 can be adjusted. The adjustment of the exposure conditions described herein may be to adjust the exposure time of the optical sensing unit 14, the exposure intensity, or to adjust the combination of the exposure time and the exposure intensity, or to change the amount of light emitted by the illumination device 12 to adjust the light of the reflected light. strength.

For example, suppose the image signal is divided into 25 blocks, and each block is arranged according to the average value of brightness, and is named B1, B2, B3, ..., B25 from high to low. In this method, a plurality of consecutive blocks after sorting are selected, for example, blocks B1 to B5 are selected. The average of all the pixel luminance signals in the blocks B1 to B5 is calculated, and the exposure conditions are adjusted according to the average value. On the next execution of this step, B2 to B6 are selected, and the average values of all the pixel luminance signals in the blocks B2 to B6 are calculated, and the exposure conditions are adjusted according to the average value. This step can be repeated until the block B21 to B25 is selected.

If the average value of all the pixel luminance signals in the blocks B1 to B5 is "100", the set target luminance value is "150". The difference signal at this time is "+50", which means that the brightness of the selected block is dark. The processor 18 can lengthen the exposure time of the optical sensing unit 14, enhance the exposure intensity of the optical sensing unit 14, or increase the luminous intensity of the illumination device 12.

If the average value of all the pixel luminance signals in the blocks B21 to B25 is "200", the set target luminance value is "150". The difference signal at this time is "-50", which means that the brightness of the selected block is bright. The processor 18 can reduce the exposure time of the optical sensing unit 14, reduce the exposure intensity of the optical sensing unit 14, or reduce the luminous intensity of the illumination device 12.

When adjusting the shooting parameters, you can set one of the adjacent ones in time to be adjusted or in a multi-stage manner. If it is in a multi-stage manner, multiple progressive increase or decrease target values can be set. For example, if the average is "50" and the final target value is "180". In the first adjustment, the brightness value is first adjusted to "100", then adjusted to "140", and finally, to the target value "180". In other words, the brightness of the image can be adjusted to the target value after the time of capturing three images.

After adjusting the exposure conditions, the optical sensing module 10 can capture a new image signal with the new exposure conditions. Moreover, the optical sensing module 10 can analyze the image signal to obtain an image quality signal corresponding to the image signal.

Then, in step S107, by repeating S103 and S105, a plurality of image signals and a plurality of image quality signals corresponding to the plurality of image signals are obtained.

In the above example, the optical sensing module 10 can adjust different exposure conditions according to different blocks (for example, blocks B1-B5, blocks B2-B6, blocks B3-B7...blocks B21-B25). Under different exposure conditions, the optical sensing module 10 can capture a plurality of image signals and correspondingly generate different image quality signals.

Finally, in step S109, after a plurality of different image signals are generated, one of the image signals having the best image quality signal can be selected, and the exposure condition of the image signal is used as the setting. An optimal exposure condition for the working surface.

Through the above steps, the optical sensing module 10 can automatically adjust its exposure conditions, so that the optical sensing module 10 can adapt to different working surfaces, and reduce the brightness and unevenness of the light reflected by the working surface, and determine the moving direction and distance. The probability of deviation.

In order to further improve the accuracy of determining the moving direction and distance, the present invention further proposes an embodiment. Please refer to FIG. 3 , which is a flowchart of a second embodiment of a method for adjusting exposure conditions of an optical sensor module disclosed in the present invention.

Steps S201 to S209 are the same as steps S101 to S109, and therefore are not described herein.

In step S211, the processor 18 performs a motion estimation process based on the plurality of video signals to generate a reliability value signal. The motion estimation side program processes the image signals adjacent to each other in time series. The processor 18 can find an image feature in the chronologically located image signal of the former, and search for the identification result similar to the image feature in the image signal located in the latter. The difference between these identification results and image features can be converted into a cost function. The processor 18 selects the most approximate identification result and the second approximation identification result according to the cost function, and calculates the difference between the cost function of the most approximate identification result and the cost function of the sub-approximation identification result as reliability. Value signal. If the difference between the cost functions is greater, it means that the reliability value is higher, and vice versa.

In step S213, the processor 18 determines the relative magnitude of the reliability value signal and the threshold according to a preset threshold value. If the reliability value signal is less than the threshold value, it means that the current exposure condition may not be suitable for the working surface at this time. Therefore, the processor 18 re-executes steps S201 through S209 to generate another exposure condition to accommodate the work surface at this time.

The accuracy of determining the direction and distance of movement is further improved by the above-described method. Although the present invention has been disclosed above in the foregoing embodiments, it is not intended to limit the present invention. It is within the scope of the invention to be modified and modified without departing from the spirit and scope of the invention. Please refer to the attached patent application for the scope of protection defined by the present invention.

10. . . Optical sensor module

12. . . Illuminating device

14. . . Optical sensing unit

16. . . Memory

18. . . processor

FIG. 1 is a schematic structural view of an image capturing device according to the present invention;

2 is a flowchart of a first embodiment of a method for adjusting exposure conditions of an optical sensing module disclosed in the present invention;

FIG. 3 is a flow chart of a second embodiment of a method for adjusting exposure conditions of an optical sensing module disclosed in the present invention.

Claims (12)

A method for adjusting an exposure condition of an optical sensing module, the optical sensing module being used for a pointing device, the method comprising: (A) receiving a reflected light reflected by a working surface; (B) illuminating according to the reflected light The optical sensing module generates an image signal, comprising a plurality of brightness signals and an image quality signal, wherein the step (B) comprises: dividing the image signal into a plurality of blocks, corresponding to the plurality of brightness signals; and according to a brightness And arranging the brightness signals; (C) setting an exposure condition of the optical sensor module according to the plurality of brightness signals, wherein the step (C) comprises: selecting a portion according to an arrangement order of the brightness signals And averaging the brightness signals; and setting the exposure condition of the optical sensor module according to an average value of the brightness signals; (D) repeating the step (B) and the step (C), The optical sensing module generates a plurality of the image quality signals according to the different exposure conditions, wherein the step (D) comprises: selecting different portions each time according to the arrangement order of the brightness signals Of the signal to set different exposure conditions; and in the different exposure conditions, the image corresponding to produce different quality The signal; and (E) setting an optimal exposure condition corresponding to the working surface according to the image quality signal under the different exposure conditions. The method of claim 1, wherein the step (C) further comprises: setting a target brightness value; comparing the target brightness value with the average of the brightness signals to generate a difference signal; and according to the difference signal Setting the exposure condition of the optical sensing module. The method of claim 1, wherein the exposure condition is one of an exposure time and an exposure intensity of the optical sensing module. The method of claim 1, wherein the exposure condition is a light intensity of the reflected light. The method of claim 1, wherein the image quality signal represents an average contrast of the image signal. The method of claim 1, further comprising: (F) performing a motion estimation procedure based on the plurality of video signals to generate a reliability value signal; and (G) when the reliability value signal is lower than one When the threshold is exceeded, perform step (A) to step (E) again. An optical sensing module is used for a pointing device. The pointing device generates a displacement signal by detecting a relative motion with a working surface, and the optical sensing module includes a displacement signal. The optical sensing module includes: : a plurality of optical sensing units for periodically receiving light reflected by the working surface and sequentially generating a plurality of image signals, each of the image signals comprising a plurality of brightness signals and an image quality signal; and a processor And according to the brightness signal of each of the image signals, sequentially setting an exposure condition of the optical sensing module, and setting a maximum corresponding to the working surface according to the image quality signal under different exposure conditions. Preferably, the optical sensing unit is divided into a plurality of blocks, corresponding to the plurality of brightness signals, the processor is configured to arrange the brightness signals according to a brightness level, and according to a sequence of the brightness signals Selecting and averaging a portion of the brightness signals, and then setting the exposure conditions of the optical sensor module according to an average value of the brightness signals; wherein the processor is in accordance with the order of the brightness signals, each time Selecting different portions of the brightness signals to set different exposure conditions; and under different exposure conditions, correspondingly generating no The quality of the image signal. The optical sensor module of claim 7, wherein the processor compares a target brightness value with the average of the brightness signals to generate a difference signal; and, according to the difference signal, sets the optical sensor module The exposure conditions. The optical sensing module of claim 7, wherein the exposure condition is one of an exposure time and an exposure intensity of the optical sensing module. The optical sensing module of claim 7, wherein the exposure condition is a light intensity of the reflected light. The optical sensing module of claim 7, wherein the image quality signal represents an average contrast of the image signal. The optical sensor module of claim 7, wherein the processor is further configured to perform a motion estimation process based on the plurality of image signals to generate a reliability value signal; and when the reliability value signal is lower than The optical sensing module resets another optimal exposure condition at a threshold.