CN103513791B - Displacement detection device - Google Patents

Abstract

A displacement detection device comprises a light source, an image sensor and a processing unit. The light source is used to illuminate a working surface. The image sensor is used to obtain reflected light from the working surface to output an image frame. The processing unit selects a settable sampling range with the largest image feature value in the image frame, and calculates the displacement of the displacement detection device according to the settable sampling range.

Description

Displacement detection device

technical field

The invention relates to an interactive device, in particular to a displacement detection device which can dynamically select an effective pixel range in an image frame to calculate displacement.

Background technique

A known optical mouse generally includes a light source, an image sensor, and a processing unit, and is manipulated by a user on a work surface. The light source is used to illuminate the work surface; the image sensor receives reflected light from the work surface to output an image frame; the processing unit calculates the The displacement of the optical mouse relative to the work surface is calculated, for example, according to the correlation between image frames.

In the known optical mouse, since the reflected light of the work surface is acquired by the image sensor, when the image quality of the image frame acquired by the image sensor is not good, it may not be possible to correctly calculate the The situation of displacement.

For example, as shown in FIG. 1 , a general optical mouse includes a light source 81 , the light source 81 illuminates the work surface 9 through a lens 82 , and the reflected light of the work surface 9 is received by an image sensor 84 through another lens 83 . When the optical mouse is assembled, the image sensor 84 may not be accurately set at the desired position, for example, when the image sensor 84 is set at the position 84', the image sensor 84 acquires all The image quality of the image frame formed by the reflected light of the working surface 9 may be poor, thus causing miscalculation.

In addition, even if the image sensor 84 is correctly positioned at a desired position, when the optical mouse is operated on a different work surface, the imaging position may still be shifted. For example with reference to shown in Fig. 2A, it shows the schematic diagram that optical mouse is operated on glass surface, and the reflected light of described working surface 9 can still be received by described image sensor 84 this moment; When another glass surface with a larger thickness is used, as shown in FIG. 2B , the image sensor 84 cannot correctly receive the reflected light from the working surface 9 , and the image quality is degraded, resulting in miscalculation.

In view of this, the present invention also proposes a displacement detection device, which can be operated on various surfaces and can effectively overcome the degradation of image quality caused by assembly errors.

Contents of the invention

The object of the present invention is to provide a displacement detection device, which can overcome the reduction of calculation accuracy caused by assembly errors.

Another object of the present invention is to provide a displacement detection device, which can adjust a settable sampling range (window of interest) of an image frame according to different working surfaces, so as to increase calculation accuracy.

The invention provides a displacement detection device, which includes a light source, an image sensor and a processing unit. The light source illuminates the work surface in a projection direction. The image sensor is used to acquire reflected light of the working surface to output an image frame. The processing unit selects at least one settable sampling range in the image frames, and calculates the displacement of the displacement detection device according to the settable sampling ranges of the two image frames respectively.

The invention also provides a displacement detection device, which includes a light source, an image sensing array, an adding unit, an analog/digital unit and a processing unit. The light source illuminates the work surface in a projection direction. The image sensing array is used to acquire reflected light of the working surface to output a first simulated image frame. The adding unit subtracts a DC value from the first analog image frame to output a second analog image frame. The analog/digital unit amplifies the second analog image frame and converts it into a digital image frame. The processing unit selects at least one settable sampling range in the digital image frame, and calculates the displacement of the displacement detection device according to the settable sampling range. This implementation manner can be used to increase the image feature value when the image feature of the image frame is relatively inconspicuous.

The invention also provides a displacement detection device, which includes a light source, an image sensor and a processing unit. The light source illuminates the work surface in a projection direction. The image sensor is used to acquire reflected light of the working surface to output an image frame. The processing unit selects a settable sampling range with the largest image feature value in the image frame, and calculates the displacement of the displacement detection device according to the settable range.

In the displacement detection device of the present invention, the reflected light from the working surface is completely received by using an image sensing array with a larger area (for example, 32×128), wherein the image sensing array is preferably rectangular and its length It preferably extends in the direction of the horizontal component of the projection direction of the light source.

The present invention also selects at least one settable sampling range or the settable sampling range with the largest image feature value in the image frame acquired by the image sensor, so as to correctly calculate the displacement according to the pixel range with obvious image features Wherein, the largest image feature value refers to the one with the largest average image feature value in the pixel range where the image feature exceeds the preset feature value, such as the largest average image quality value or the largest average image brightness.

Description of drawings

FIG. 1 shows a schematic diagram of a known optical mouse, which shows the assembly deviation of the image sensor.

2A and 2B are schematic diagrams illustrating the operation of a known optical mouse operating on glass surfaces of different thicknesses.

FIG. 3 is a schematic diagram of a displacement detection device according to an embodiment of the present invention, which shows an assembly deviation of an image sensor.

Fig. 4 shows a schematic diagram of the operation of the displacement detection device according to the embodiment of the present invention.

5A and 5B are schematic diagrams showing the operation of the displacement detection device according to the embodiment of the present invention operating on glass surfaces with different thicknesses.

Fig. 6 shows a schematic block diagram of a displacement detection device according to an embodiment of the present invention.

Explanation of reference signs

1 displacement detection device 11, 81 light source

13, 13', 13" image sensor 130, 130' can set the sampling range

131 Image sensing array 133 Adding unit

135 analog/digital units 15 processing units

16 digital/analog unit 17, 19 optics

S, 9 working surface P projection direction

P _X projection direction horizontal component P _Y projection direction vertical component

L _X image sensing array length direction I _F image frame

DAC DC value D _X average brightness

A _X , Ay brightness characteristic change T ₁ , T ₂ glass thickness

82, 83 optics V 84, 84' image sensor

detailed description

In order to make the above and other objects, features and advantages of the present invention more apparent, the following will be described in detail with accompanying drawings. In the description of the present invention, the same components are denoted by the same symbols, and will be described first.

Referring to FIG. 3 , it shows a schematic diagram of a displacement detection device 1 according to an embodiment of the present invention. The displacement detection device 1 includes a light source 11, an image sensor 13, and a processing unit 15; in some embodiments, the displacement detection device 1 may also include an optical element 17 (such as a lens) for adjusting the projection range of the light source 11 and The optical element 19 (such as a lens) is used to increase the light-sensing efficiency of the image sensor 13 . The displacement detection device 1 is used to detect the displacement relative to the working surface S, and output the displacement to an electronic device (not shown) for corresponding control. It must be noted that the displacement detection device 1 in FIG. 3 actually only includes one image sensor 13, 13' or 13", and three image sensors are shown here to indicate assembly deviation, that is, the The image sensor may be located at one of 13, 13' or 13", which does not mean that the displacement detection device 1 includes three image sensors.

The light source 11 can be, for example, a light emitting diode or a laser diode for emitting infrared light or invisible light to provide the light required for the image sensor 13 to capture images. The light source 11 illuminates the work surface S with a projection direction P, wherein the projection direction P can be decomposed into a horizontal component P _X parallel to the work surface S and a vertical component P _Y perpendicular to the work surface.

The image sensor 13 is preferably a CMOS image sensor or other active image sensor, which is used to obtain the reflected light of the working surface S to continuously output the image frame I _F ; wherein, the image frame I _F for digital image frames. The image sensor 13 preferably includes a rectangular image sensing array 131; the length direction L _X of the image sensing array 131 extends approximately in the direction of the horizontal component P _X of the projection direction P, and the image sensing array 131 The measurement array 131 has, for example, a pixel size of 32×128, but the present invention is not limited thereto. Thereby, regardless of whether the image sensor 13 is arranged at the position of 13, 13' or 13" when assembled as shown in the figure, the image sensor 13 can detect the reflected light from the working surface S It can be understood that the position offset of 13, 13' or 13" is actually very small, and the spatial scale is enlarged in Fig. 3 for the purpose of representation.

The processing unit 15 may be, for example, a digital signal processor (DSP), which is used to select at least one settable sampling range 130 from the image frame _IF output by the image sensor 13, and according to the settable The sampling range 130 is set to calculate the displacement of the displacement detection device 1 , for example, the displacement is calculated according to the correlation between the settable sampling ranges 130 of the two image frames _IF . In one embodiment, the at least one settable sampling range 130 is defined as one or more ranges of pixels where the image feature of the image frame _IF exceeds a preset feature value, wherein the image feature can be, for example, image quality or image brightness. In other words, the processing unit 15 of the displacement detection device 1 of the present invention does not use the entire image frame _IF output by the image sensor 13 to calculate the displacement, but dynamically utilizes the pixel range with obvious image features Calculation.

Referring to Fig. 4, when the image frame _IF is determined to include a plurality of configurable sampling ranges, for example, 130 and 130' are included here, the processing unit 15 performs the processing on the image sensor 13. Select the settable sampling range (for example, 130) with the largest image feature value or the largest area in the image frame _IF output from 13, and calculate the displacement detection device 1 according to the settable sampling range 130. Regardless of the amount of displacement, the sampling range 130' can be set. In other implementations, the processing unit 15 can also calculate the displacement according to different settable sampling ranges, for example, calculate the first displacement according to the settable sampling range 130 and calculate the first displacement according to the settable sampling range 130′ The second displacement amount, and compare the consistency of the displacement amount calculated according to different settable sampling ranges, so when the image characteristic value is not obvious (for example, when operating on a working surface S with a low reflection coefficient), it can be used for Double check that the displacement is correct. The largest image feature value refers to the one with the largest average image feature value among the ranges of pixels whose image features exceed preset feature values, such as the largest average image quality value or the largest average image brightness.

In addition to overcoming assembly errors, the displacement detection device 1 according to the embodiment of the present invention can also adjust the settable sampling range 130 of the image sensor 13 according to different working surfaces S. For example, refer to FIGS. 5A and 5B , which respectively show schematic diagrams of the operation of the displacement detection device 1 on glass surfaces with different thicknesses. When the displacement detection device ₁ operates on the working surface S with a first thickness T1, the settable sampling range 130 is, for example, located on the leftmost side of the image sensing array 130 in the figure, and when the displacement detection When the device 1 operates on the working surface S having the second thickness T ₂ , the settable sampling range 130 is, for example, shifted toward the right side of the image sensing array 130 in the figure. As mentioned above, the processing unit 15 can identify one or more pixel ranges in which the image feature of the image frame _IF exceeds a preset feature value as the settable sampling range 130, and calculate the the amount of displacement.

In addition, in order to increase the accuracy of selecting the settable sampling range 130, when the image features of the image frame _IF are all smaller than the preset feature value or each image frame _IF is output, the image The sensor 13 also performs the steps of subtracting the DC value from the analog image frame and amplifying the analog image frame with the subtracted DC value, and then digitizing to output the analog image frame I _F .

Referring to FIG. 6 , it shows a schematic block diagram of a displacement detection device 1 according to an embodiment of the present invention; wherein, the image sensor 13 further includes an image sensing array 131 , an adding unit 133 and an analog/digital unit 135 . In this embodiment, the light source 11 also illuminates the working surface S in the projection direction P. The image sensing array 131 is used to acquire the reflected light of the working surface S to output a first simulated image frame; the first simulated image frame is, for example, a two-dimensional simulated image, wherein FIG. 6(A) shows, for example, the The luminance value (Dx+Ax) of a column of pixels in the first analog image frame, Dx represents the average luminance and Ax represents the luminance characteristic change value. The adding unit 133 (which can also be realized by a subtractor) subtracts the DC value DAC from the first analog image frame to output a second analog image frame, where FIG. 6(B) shows, for example, the second analog image frame The luminance value (Dx-DAC)+Ax of a column of pixels; the purpose of subtracting the DC value DAC from the luminance value (Dx+Ax) is to avoid the situation that the luminance value is too large in the subsequent amplification and digitization steps. The analog/digital unit 135 amplifies the second analog image frame and converts it into a digital image frame for output to the processing unit 15, wherein FIG. 6(C) shows, for example, a column of pixels of the digital image frame Luminance value (Dx-DAC) + Ay, Ay represents a luminance characteristic change value; it can be clearly seen that the peak-to-peak value of the luminance characteristic is effectively increased. In this embodiment, the analog/digital unit 135 can be, for example, a linear or non-linear analog/digital converter, or the analog/digital unit 135 can also include an amplification unit, which first amplifies the second analog image frame and then , and then perform analog/digital conversion. Thereby, after the first analog image frame sensed by the image sensing array 131 is processed by the adder 133 and the digital/analog unit 135, the image feature value of the digital image frame can be increased to increase the selectable Determine the correctness of the sampling range.

In addition, in this embodiment, the direct current value DAC is, for example, the average brightness or offset of the second analog image frame, which can be determined by the processing unit 15 according to the digital image frame, and passed through the digital/analog unit 16 Convert the average brightness or the offset into an analog signal and input it to the adding unit 133 .

In addition, during actual operation, the processing unit 15 can confirm whether the selected settable sampling range 130 is appropriate at an appropriate time. For example, the processing unit 15 calculates the image feature value of the selected settable sampling range 130 every preset time interval, when the image feature value of the settable sampling range 130 is smaller than the preset feature value value, then reselect at least one settable sampling range 130 or the settable sampling range 130 with the largest image feature value; or, the processing unit 15 directly reselects at least one settable sampling range every preset time interval The range 130 or the settable sampling range 130 with the largest image feature value. In addition, the settable sampling range 130 can be selected, for example, every time the system is turned on or when the sleep state is ended, or can be selected according to a user's instruction.

To sum up, it is known that the optical mouse cannot eliminate assembly errors and may fail to correctly receive reflected light from the work surface when operating on different work surfaces, resulting in misoperation. The present invention also proposes a displacement detection device (Figures 3 to 5), which uses an image sensing array with a larger area and selects a settable sampling range, since only part of the pixel range with obvious image features is used for calculation, so It can effectively overcome assembly errors and is applicable to different working surfaces.

Although the present invention has been disclosed in the foregoing embodiments, it is not intended to limit the present invention. Any person skilled in the art to which the present invention belongs can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims (18)

1. A displacement detection device, which displacement detection device comprises: a light source for illuminating the work surface in a projection direction; an image sensor for capturing reflected light from the work surface to output an image frame; and The processing unit selects at least one settable sampling range according to one or more pixel ranges whose image characteristics exceed a preset characteristic value in the image frame output by the image sensor, and ignores the pixel range output by the image sensor. For the pixel range outside the settable sampling range in the image frame, the settable sampling range is calculated according to the correlation between the settable sampling ranges respectively selected in the two image frames output by the image sensor. The displacement of the displacement detection device, Wherein, the displacement detection device adjusts the position of the settable sampling range of the image frame according to different working surfaces. 2. The displacement detection device according to claim 1, wherein the image characteristic is image quality or image brightness. 3. The displacement detection device according to claim 1, wherein when the image features of the image frames are all smaller than the preset feature value, the image sensor also performs subtracting a DC value from the analog image frame and A step of amplifying the simulated image frame from which the DC value has been subtracted, and then outputting the image frame. 4 . The displacement detection device according to claim 1 , wherein the image sensor comprises a rectangular image sensing array, and the length direction of the image sensing array extends in the direction of the horizontal component of the projection direction. 5. The displacement detection device according to claim 1, wherein the processing unit further compares the consistency of the displacement calculated according to different settable sampling ranges. 6. A displacement detection device, the displacement detection device comprising: a light source for illuminating the work surface in a projection direction; An image sensor, including an image sensing array, an addition unit and an analog/digital unit, The image sensing array is used to acquire the reflected light of the working surface to output the first analog image frame; The adding unit subtracts a DC value from the first analog image frame to output a second analog image frame; and the analog/digital unit amplifies the second analog image frame and converts the second analog image frame into a digital image frame; and A processing unit that selects at least one settable sampling range according to one or more pixel ranges whose image characteristics exceed a preset characteristic value in the digital image frame output by the image sensor, and ignores the image sensor output The range of pixels outside the settable sampling range in the digital image frame, and according to the correlation between the settable sampling ranges respectively selected in the two digital image frames output by the image sensor to calculate the displacement of the displacement detection device, Wherein, the displacement detection device adjusts the position of the settable sampling range of the image frame according to different working surfaces. 7. The displacement detection device according to claim 6, wherein the DC value is an average brightness or an offset of the second analog image frame. 8. The displacement detection device according to claim 6, wherein the image characteristic is image quality or image brightness. 9. The displacement detection device according to claim 6, wherein the image sensing array is rectangular, and the length direction of the image sensing array extends in the direction of the horizontal component of the projection direction. 10. The displacement detection device according to claim 6, wherein the size of the image sensing array is 32×128. 11. The displacement detection device according to claim 6, wherein the processing unit further compares the consistency of the displacement calculated according to different settable sampling ranges. 12. A displacement detection device, the displacement detection device comprising: a light source for illuminating the work surface in a projection direction; an image sensor for capturing reflected light from the work surface to output an image frame; and The processing unit selects a settable sampling range with the largest image feature value in one or more pixel ranges in which the image feature of the image frame output by the image sensor exceeds a preset feature value, and ignores the image sensing The range of pixels outside the settable sampling range in the image frame output by the image sensor, and according to the correlation between the settable sampling ranges respectively selected in the two image frames output by the image sensor to calculate the displacement of the displacement detection device, Wherein, the displacement detection device adjusts the position of the settable sampling range of the image frame according to different working surfaces. 13. The displacement detection device according to claim 12, wherein the image feature value is image quality or image brightness. 14. The displacement detection device according to claim 12, wherein the image sensor comprises a rectangular image sensing array, the length direction of the image sensing array extends in the direction of the horizontal component of the projection direction. 15 . The displacement detection device according to claim 12 , wherein the processing unit calculates the image feature value of the settable sampling range every preset time interval. 16. The displacement detection device according to claim 15, wherein when the image feature value of the settable sampling range is smaller than the preset feature value, reselect the settable sampling range with the largest image feature value. 17. The displacement detection device according to claim 12, wherein the processing unit re-selects the settable sampling range with the largest image feature value every preset time interval. 18. The displacement detection device according to claim 12, wherein when the image feature values of the image frames are all smaller than the preset feature values, the image sensor also performs subtracting a DC value from the analog image frame and a step of amplifying the analog image frame from which the DC value has been deducted, and then outputting the image frame.