CN103309516A - Optical touch device and detection method thereof - Google Patents

Abstract

An optical touch device comprises a light source, a light source control unit, a light guide piece, an image sensor and a processing unit. The light source control unit controls the light source to emit light at different brightness. The light guide member is provided with a light incident surface, a touch surface and a light emitting surface, wherein the light source emits incident light into the light guide member from the light incident surface, a plurality of microstructures are formed inside the light guide member and/or on the light emitting surface, and the microstructures are used for reflecting the incident light towards the touch surface to form scattered light. The image sensor receives the reflected light emitted from the light emitting surface to generate corresponding image frames corresponding to different brightness of the light source. The processing unit calculates a differential image frame of the image frames and determines an operation state based on the differential image frame.

Description

Optical touch device and detection method thereof

technical field

The invention relates to a man-machine interface device, in particular to an optical touch device capable of detecting suspended objects and contact objects and a detection method thereof.

Background technique

The touch system does not need to be equipped with separate peripheral devices during use, so it has excellent operational convenience and is suitable for various human-machine interface devices. Optical touch systems usually use light sensors to detect the reflected light of fingers to judge Finger position or gesture.

For example, FIG. 1A shows a schematic diagram of a known optical touch device. The optical touch device 8 includes a light source 81 , a light guide plate 82 and a light sensor 83 . The light source 81 injects the incident light 811 from the light incident surface 821 of the light guide plate 82 , which can face away from the light incident surface 821 in the light guide plate 82 due to the total reflection phenomenon of the light guide plate 82 direction transfer. When a finger touches the touch surface 822 of the light guide plate 82, the total reflection condition of the touch surface 822 can be destroyed, and part of the incident light 811 is reflected by the finger and emitted from the light output surface 823 of the light guide plate 82. The reflected light 812 is emitted and received by the light sensor 83 . However, this optical touch device 8 can only be used to detect a finger touching the touch surface 822 , and cannot perform hovering detection.

1B is a schematic diagram of another optical touch device disclosed in US Patent Publication No. 20090267919, titled "Multi-touch Position Tracking Device, Interaction System Using the Device, and Multi-Point Interactive Image Processing Method". The optical touch device 9 also includes a light source 91 , a light guide plate 92 and a light sensor 93 . The light source 91 injects incident light 911 from the light incident surface 921 of the light guide plate 92 , part of the incident light 911 can be directed away in the light guide plate 92 due to the total reflection phenomenon on the surface of the light guide plate 92 . The direction of the light incident surface 921 is transferred. A concave-convex structure is formed on the touch surface 922 of the light guide plate 92 to destroy the total reflection condition of the touch surface 922, so that part of the incident light 911 can exit the light guide plate 92 from the touch surface 922. . When the finger is close to the touch surface 922, the light emitted from the touch surface 922 can be reflected, making it become the reflected light 912 emitted toward the light emitting surface 923 of the light guide plate 92 and detected by the light sensor 93. take over. In this way, the optical touch device 9 can detect floating objects.

The present invention proposes an optical touch device and a detection method thereof capable of simultaneously detecting suspended objects and contact objects, which also has the advantage of eliminating ambient light interference.

Contents of the invention

The object of the present invention is to provide an optical touch device and a detection method thereof, which are used for detecting the operating state of an object.

Another object of the present invention is to provide an optical touch device and a detection method thereof, which can eliminate the interference of ambient light.

The invention provides an optical touch device, which includes a light source, a light source control unit, a light guide, an image sensor and a processing unit. The light source control unit controls the light source to emit light with different brightness. The light guide has a light incident surface, a touch surface and a light output surface, wherein the light source injects incident light from the light incident surface into the light guide, and the inside of the light guide and/or the light guide A plurality of microstructures are formed on the light emitting surface, and the microstructures are used to reflect the incident light toward the touch surface and make it into scattered light. The image sensor receives the reflected light emitted from the light emitting surface to generate corresponding image frames corresponding to different brightnesses of the light source. The processing unit calculates a difference image frame of the image frame and judges an operation state according to the difference image frame.

The invention also provides a detection method of the optical touch device. The optical touch device includes a light source, a light guide, an image sensor, and a processing unit; the light guide has a light incident surface, a touch surface, and a light exit surface, and the inside of the light guide and/or the light exit surface Multiple microstructures are formed. The detection method includes the following steps: using the light source to emit light with a first brightness and a second brightness in turn; using the image sensor to obtain the light source incident on the light guide and reflected by the microstructure at a sampling frequency The reflected light is reflected toward the touch surface, and then emitted from the light-emitting surface to generate a first image frame corresponding to the first brightness, and generate a second image frame corresponding to the second brightness; using the The processing unit calculates a difference image frame of the first image frame and the second image frame; and the operation state is determined by the processing unit according to a comparison result of the difference image frame and two thresholds.

The invention also provides a detection method of the optical touch device. The optical touch device includes a light source, a light guide, an image sensor, and a processing unit; the light guide has a light incident surface, a touch surface, and a light exit surface, and the inside of the light guide and/or the light exit surface Multiple microstructures are formed. The detection method includes the following steps: using the light source to emit light with the first brightness, the second brightness and the third brightness in turn; The reflection of the microstructure is reflected toward the touch surface, and then the reflected light is emitted from the light-emitting surface to generate a first image frame corresponding to the first brightness, and generate a second image frame corresponding to the second brightness , and generate a third image frame corresponding to the third brightness; use the processing unit to calculate the first difference image frame of the first image frame and the third image frame, and calculate the second image frame and a second differential image frame of the third image frame; and using the processing unit to determine an operating state according to a comparison result of the first differential image frame and the second differential image frame with at least one threshold.

In the optical touch device of the present invention, the microstructure is formed on the opposite surface of the touch surface and/or inside the light guide member, but not formed on the touch surface, and the microstructure The structure is used to reflect the incident light so that it emits scattered light toward the touch surface, wherein the formation method of the microstructure is not limited, for example, printing, sandblasting, etching, atomization and mold pressing can be used. Various shapes of microstructures such as convex, concave-convex or concave are formed by different methods. In other words, the light guide plate uses a non-zero order design to form a scattered light field that rapidly decays with distance in front of the touch surface; when an object enters the scattered light field, it can The reflected light is reflected toward the light guide member for detection by the image sensor located on the side of the light emitting surface.

In the optical touch device of the present invention, the differential image acquired by the image sensor is used to determine the floating object or the contacting object, so the influence of ambient light can be effectively eliminated, thereby increasing the accuracy of judgment.

In the optical touch device and detection method thereof of the present invention, the reflected light emitted from the light-emitting surface is the scattered light reflected by the microstructure when an object on the side of the touch surface approaches and/or touches the touch surface. light and make it pass through the light guide to form.

Description of drawings

1A and 1B illustrate schematic diagrams of known optical touch devices.

2A to 2C illustrate schematic diagrams of an optical touch device according to an embodiment of the present invention.

FIG. 3 shows a schematic diagram of image acquisition and light source lighting in the optical touch device according to the embodiment of the present invention.

FIG. 4 shows a flowchart of a detection method of an optical touch device according to an embodiment of the present invention.

FIG. 5 shows a flowchart of a detection method of an optical touch device according to another embodiment of the present invention.

6A to 6C show schematic diagrams of difference image frames and thresholds in an embodiment of the present invention.

Explanation of reference signs

1 Optical touch device 11 Light source

111 incident light 112 scattered light

113 Reflected light 12 Light source control unit

13 Light guide 131 Light incident surface

132 touch surface 133 light emitting surface

134, 134′ microstructure 14 image sensor

15 processing unit 16 transmission interface unit

2. 2′ object f1-f3 image frame

S ₃₁ -S ₃₄ , S ₄₁ -S ₄₄ Step 8, 9 Optical touch device

81, 91 light source 82, 92 light guide plate

811, 911 incident light 812, 912 reflected light

821, 921 incident surface 822, 922 touch surface

823, 923 light exit surface 83, 93 light sensor

Th ₁ , Th ₂ , TH ₁ , TH ₂ threshold f ₁ -f ₂ , f ₁ -f ₃ , f ₂ -f ₃ differential image frames

Detailed ways

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 FIGS. 2A to 2C , they are schematic diagrams of an optical touch device according to an embodiment of the present invention. The optical touch device 1 is used to detect the operation state of the object 2, wherein the object 2 can be a finger, a stylus or other touch elements, without specific limitation, as long as it can reflect the light emitted by the light source. The operation state includes a hovering state, such as the object 2, and a touch state, such as the object 2'. In addition, the optical touch device 1 can also be used for multi-touch, not limited to single-touch.

The optical touch device 1 of this embodiment includes a light source 11, a light source control unit 12, a light guide 13, an image sensor 14, a processing unit 15, and a transmission interface unit 16; wherein, the light source control unit 12 can be included in the processing In the unit 15 or independently of the processing unit 15, there is no specific limitation.

The light source 11 is preferably a light emitting diode for emitting infrared light, red light or other invisible light, for example. The light source 11 is used to inject the incident light 111 from the light incident surface 131 of the light guide 13 into the inside of the light guide 13 , and transmit it in a direction away from the light incident surface 131 . In other words, the light source 11 is disposed relative to the light incident surface 131 .

The light source control unit 12 is used for controlling the light source 11 to emit light with different brightness. The purpose of the light source 11 emitting light with different brightness is to eliminate the interference of ambient light by calculating the difference image frame in the post-processing (details will be described later). The light source control unit 12 is controlled by the processing unit 15 to make the light source 11 emit light in synchronization with the image acquisition of the image sensor 14 , as shown in FIG. 3 .

The light guide member 13 can be made of transparent material relative to the light emitted by the light source 11 , such as glass or plastic, but is not limited thereto. The light guide 13 has the light incident surface 131 , the touch surface 132 and the light exit surface 133 ; wherein the touch surface 132 and the light exit surface 133 are opposite to each other. The object 2 is located on one side of the touch surface 132 for manipulation; wherein, the controllable functions are similar to common optical touch devices, so details are not repeated here. In this embodiment, a plurality of microstructures 134 are formed on the light emitting surface 133 (inner surface or outer surface) of the light guide member 13 (as shown in FIGS. 2A and 2B ) and/or formed inside the light guide member 13 A plurality of microstructures 134' (as shown in FIG. 2C); wherein, the microstructures 134 can be formed into convex, concave-convex, or concave shapes by printing, sandblasting, etching, atomization, and mold pressing, for example. Microstructures of various shapes, microstructures 134′ can be, for example, air, ink or other substances mixed therein when making the light guide 13, and there is no specific limitation, as long as they can reflect the incident light 111 from the light source 11 That's it. The microstructures 134 and 134 ′ are used to reflect the incident light 111 toward the touch surface 132 into scattered light 112 to exit the light guide 13 , and the scattered light 112 is received by the touch surface 132 The reflection of the objects 2 , 2 ′ on the side becomes reflected light 113 , which passes through the light guide 13 again and exits from the light exit surface 133 . In this embodiment, the ratio of the total area of the microstructures 134, 134' to the area of the light-emitting surface 133 is preferably between 10% and 75%, so that the microstructures 134, 134' can reflect enough incident light 111 , and make enough reflected light 113 pass through the light-emitting surface 133 .

The image sensor 14 can be, for example, a CCD image sensor, a CMOS image sensor, or other sensors for sensing light energy, which is arranged on the side of the light-emitting surface 133 to receive and acquire the light emitted from the light-emitting surface 133 at a sampling frequency. The reflected light 113 generates corresponding image frames corresponding to different brightnesses of the light source 11 (details will be described later), and is sent to the processing unit 15 for post-processing.

The processing unit 15 calculates a difference image frame of the image frame, and judges the operation state according to the difference image frame.

The transmission interface unit 16 is used for wired or wireless transmission of the operation status to related electronic devices for corresponding control.

Referring to FIGS. 2A-2C, 3, 4 and 6A, FIG. 3 shows a schematic diagram of image acquisition and light source lighting operations in an optical touch device according to an embodiment of the present invention, and FIG. 4 shows an optical touch device according to an embodiment of the present invention. Figure 6A shows a schematic diagram of difference image frames and thresholds in an embodiment of the present invention. The detection method of this embodiment includes the following steps: using the light source to emit light at the first brightness and the second brightness in turn (step S ₃₁ ); Reflect the touch surface, and then emit the reflected light from the light-emitting surface to generate a first image frame corresponding to the first brightness, and generate a second image frame corresponding to the second brightness (step S ₃₂ ); using a processing unit Computing the difference image frame of the first image frame and the second image frame (step _S33 ); and using the processing unit to judge the operating state according to the comparison result of the difference image frame and two thresholds (step _S34 ).

Step S ₃₁ : the light source control unit 12 controls the light source 11 to emit light with the first brightness (for example, a rectangle with a longer length) and the second brightness (for example, a rectangle with a shorter length) in turn, as shown in FIG. 3(B) ; Wherein, the first brightness is greater than the second brightness, and the second brightness may be zero brightness (that is, no light) or non-zero brightness.

Step _S32 : The image sensor 14 uses a fixed sampling frequency, as shown in FIG. The reflected light 113 emitted from the touch surface 132 after being reflected by the microstructures 134 and 134 ′, and reflected by the objects 2 and 2 ′, passed through the light guide 13 and emitted from the light exit surface 133 , generate a first image frame f ₁ corresponding to the first brightness, generate a second image frame f ₂ corresponding to the second brightness, and send it to the processing unit 15 for post-processing; wherein, due to the first A brightness is greater than the second brightness, the average brightness value of the first image frame _f1 is greater than the average brightness value of the second image frame _f2 .

Step S ₃₃ : the processing unit 14 calculates the difference image frame (f ₁ -f ₂ ) of the first image frame f ₁ and the second image frame f ₂ . Since each image frame f ₁ and f ₂ acquired by the image sensor 14 contains ambient light, the influence of ambient light can be effectively eliminated by calculating the difference image frame (f ₁ -f ₂ ).

_Step S ₃₄ : The processing _{unit 14} judges that the object is _in the Suspension state or contact state, as shown in Figure 6A.

For example, in one implementation, when the difference image frame (f ₁ -f ₂ ) has a brightness value or a maximum brightness value of a part of the image area greater than the first threshold Th ₁ and smaller than the second threshold Th ₂ , it means that the The object 2 has been illuminated by the scattered light 112 but has not touched the touch surface 132, so it is determined that the object 2 is in a floating state; when the difference image frame (f ₁ -f ₂ )' has the brightness of a part of the image area When the value or the maximum brightness value is greater than the second threshold _Th2 , it means that the object 2' has contacted the touch surface 132 and can reflect a large amount of the scattered light 112, so it is determined that the object 2' is in a contact state ; When the brightness value or the maximum brightness value of all pixels in the difference image frame (f ₁ -f ₂ )" is less than the first threshold Th ₁ , it means that the object is neither a floating object nor a contact object. In this embodiment, The portion of the difference image frame (f ₁ -f ₂ ) is compared to two thresholds.

In another embodiment, when the average brightness value of the difference image frame (f ₁ -f ₂ ) is greater than the first threshold Th ₁ and less than the second threshold Th ₂ , it is determined that the object 2 is in a floating state; when When the average brightness value of the difference image frame (f ₁ -f ₂ )' is greater than the second threshold Th ₂ , it is determined that the object 2' is in a contact state. In this embodiment, the overall (ie average brightness) of the differential image frames (f ₁ -f ₂ ) is compared with two thresholds.

Referring to FIGS. 2A-2C, 3, 5 and 6B, FIG. 5 shows a flow chart of a detection method for an optical touch device in another embodiment of the present invention, and FIG. 6B shows in an embodiment of the present invention, the differential image frame and Schematic diagram of the threshold. The detection method of this embodiment includes the following steps: using the light source to emit light at the first brightness, the second brightness and the third brightness in turn (step S ₄₁ ); using the image sensor to acquire the The microstructure is reflected toward the touch surface, and then the reflected light emitted from the light-emitting surface generates a first image frame corresponding to the first brightness, generates a second image frame corresponding to the second brightness, and corresponds to the The third brightness generates a third image frame (step _S42 ); use a processing unit to calculate the first difference image frame of the first image frame and the third image frame, and calculate the second image frame and the first image frame The second differential image frame of the three image frames (step _S43 ); and using the processing unit to judge the operating state according to the comparison result of the first differential image frame and the second differential image frame with at least one threshold value (step S ₄₄ ).

Step _S41 : The light source control unit 12 controls the light source 11 in turn to use the first brightness (for example, the rectangle with the longest length), the second brightness (for example, the rectangle with the second longest length) and the third brightness (for example, the rectangle with the shortest length). ) emit light, as shown in Figure 3 (C); wherein, the first brightness is greater than the second brightness, the second brightness is greater than the third brightness, and the third brightness can be zero brightness (ie not lit) or non-zero brightness.

Step _S42 : The image sensor 14 uses a fixed sampling frequency, as shown in FIG. The reflected light 113 emitted from the touch surface 132 after being reflected by the microstructures 134 and 134 ′, and then reflected by the objects 2 and 2 ′ passes through the light guide 13 and emitted from the light emitting surface 133 , generating a first image frame _f1 corresponding to the first brightness, generating a second image frame _f2 corresponding to the second brightness, and generating a third image frame _f3 corresponding to the third brightness, and transmitting to The processing unit 15 performs post-processing; wherein, since the first brightness is greater than the second brightness, and the second brightness is greater than the third brightness, the average brightness of the first image frame _f1 The value is greater than the average luminance value of the second image frame _f2 , and the average luminance value of the second image frame _f2 is greater than the average luminance value of the third image frame _f3 .

Step _S43 : The processing unit 15 calculates the first difference image frame ( _f1 - _f3 ) of the first image frame _f1 and the third image frame _f3 , and calculates the second image frame f ₂ and the second differential image frame (f ₂ -f ₃ ) of the third image frame f ₃ ; this step is also used to eliminate the influence of ambient light.

Step S ₄₄ : the processing unit 14 determines that the object is floating according to a comparison result of the first differential image frame (f ₁ -f ₃ ) and the second differential image frame (f ₂ -f ₃ ) with at least one threshold state or contact state, as shown in Figure 6B.

For example, in one embodiment, when the luminance value or the maximum luminance value of a partial image area of the first difference image frame (f ₁ -f ₃ ) is greater than the first threshold TH ₁ , and the second difference image frame (f ₂ -f ₃ ) When the luminance values or maximum luminance values of all pixels are less than the second threshold _TH2 , it means that the object 2 can be illuminated by the stronger scattered light 112 but cannot be illuminated by the weaker scattered light 112, so it is determined that the The object is in a floating state (as shown in the left figure of FIG. 6B ). When the luminance value or the maximum luminance value of the partial image area of the second differential image frame (f ₂ -f ₃ ) is greater than the second threshold TH ₂ , it means that the object 2' can be scattered weakly The light 112 illuminates, so it is determined that the object 2 ′ is in a contact state (as shown in the right diagram of FIG. 6B ); wherein, the first threshold TH ₁ may be equal to or not equal to the second threshold TH ₂ . In other words, in this implementation manner, at least a part of the first difference image frame (f ₁ -f ₃ ) and the second difference image frame (f ₂ -f ₃ ) can be compared with the same threshold or respectively compared with Comparison of different thresholds.

In another embodiment, when the average brightness value of the first difference image frame (f ₁ -f ₃ ) is greater than the first threshold TH ₁ , and the average brightness value of the second difference image frame (f ₂ -f ₃ ) When the value is less than the second threshold TH ₂ , it is determined that the object 2 is in a floating state; when the average brightness value of the second difference image frame (f ₂ -f ₃ ) is greater than the second threshold TH ₂ , it is determined that The object 2' is in a contact state; wherein, the first threshold TH ₁ may be equal to or not equal to the second threshold TH ₂ . In other words, in this implementation manner, the overall (i.e. average brightness) of the first differential image frame (f ₁ -f ₃ ) and the second differential image frame (f ₂ -f ₃ ) can be compared with the same threshold Compare or compare with different thresholds respectively.

In another embodiment, the difference image frame can also be denoised first, for example, the difference image frame is filtered to form a filtered image frame to reduce noise interference (such as using a low-pass filter) and background light interference (such as Using a high-pass filter), then compare the maximum value and/or average value of the filtered image frame with at least one threshold to determine the operating state; for example, FIG. 6C compares the difference image frame (f ₁ -f ₂ ) with the filter Convolution to form filtered image frames. It can be understood that the frequency spectrum of the filter is not limited to that shown in FIG. 6C , and can be determined according to practical applications.

In other words, in each embodiment of the present invention, the characteristic value of the difference image frame is compared with at least one threshold value to judge the operation state, wherein the characteristic value can be, for example, the maximum brightness value, the average brightness value, the filtered image frame The maximum value of and/or the average value of the filtered image frame, but is not limited to this.

To sum up, in the light guide plate of the known optical touch device, a concave-convex structure is formed on the touch surface to destroy the total reflection condition of the touch surface, so that light can be emitted from the touch surface. The present invention also proposes an optical touch device (FIGS. 2A to 2C) and a detection method thereof (FIGS. 4 and 5), wherein the touch surface of the light guide is completely free of any structure for destroying the total reflection condition, and can be detected by Compute the difference image frame to remove the interference of ambient light.

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 protection scope of the present invention should be defined by the appended claims.

Claims (20)

1. optical touch control apparatus, this optical touch control apparatus comprises:

Light source;

Light source control unit, it is luminous with different brightness that this light source control unit is controlled described light source;

Light guide, this light guide has incidence surface, touch surface and exiting surface, it is inner that wherein said light source is injected into described light guide with incident light from described incidence surface, be formed with a plurality of microstructures on described light guide inside and/or the described exiting surface, described microstructure is used for described incident light is made it to become scattered light towards described touch surface reflection;

Imageing sensor, this imageing sensor receives the reflected light that penetrates from described exiting surface, produces corresponding picture frame with the different brightness corresponding to described light source; With

Processing unit, this processing unit calculate the difference diagram picture frame of described picture frame and according to described difference diagram picture frame decision operation state.

2. optical touch control apparatus according to claim 1, it is luminous with the first brightness and the second brightness in turn that wherein said light source control unit is controlled described light source; Described imageing sensor produces the first picture frame corresponding to described the first brightness, and produces the second picture frame corresponding to described the second brightness; Described processing unit calculates the difference diagram picture frame of described the first picture frame and described the second picture frame; Described the first brightness is greater than described the second brightness.

3. optical touch control apparatus according to claim 2, wherein said processing unit also compare described difference diagram picture frame and first threshold and Second Threshold; When the eigenwert of described difference diagram picture frame during greater than described first threshold and less than described Second Threshold, be judged to be suspended state, when the described eigenwert of described difference diagram picture frame during greater than described Second Threshold, be judged to be contact condition.

4. optical touch control apparatus according to claim 3, wherein said eigenwert is maximal value and/or the mean value of maximum brightness value, average brightness value, filtering image frame.

5. according to claim 2, the described optical touch control apparatus of each claim in 3 or 4, wherein said the second zero luminance brightness or non-zero luminance.

6. optical touch control apparatus according to claim 1, it is luminous with the first brightness, the second brightness and the 3rd brightness in turn that described light source control unit is controlled described light source; Described imageing sensor produces the first picture frame corresponding to described the first brightness, produces the second picture frame corresponding to described the second brightness, and produces the 3rd picture frame corresponding to described the 3rd brightness; Described processing unit calculates the first difference diagram picture frame of described the first picture frame and described the 3rd picture frame, and calculate the second difference diagram picture frame of described the second picture frame and described the 3rd picture frame, wherein said the first brightness is greater than described the second brightness, and described the second brightness is greater than described the 3rd brightness.

7. optical touch control apparatus according to claim 6, wherein said processing unit also compare described the first difference diagram picture frame and described the second difference diagram picture frame and threshold value; When the eigenwert of described the first difference diagram picture frame greater than the eigenwert of described threshold value and described the second difference diagram picture frame during less than described threshold value, be judged to be suspended state, when the described eigenwert of described the second difference diagram picture frame during greater than described threshold value, be judged to be contact condition.

8. optical touch control apparatus according to claim 7, wherein said eigenwert is maximal value and/or the mean value of maximum brightness value, average brightness value, filtering image frame.

9. according to claim 6, the described optical touch control apparatus of each claim in 7 or 8, wherein said the 3rd zero luminance brightness or non-zero luminance.

10. optical touch control apparatus according to claim 1, the reflected light that wherein said exiting surface penetrates are that described scattered light is through the object reflection of described touch surface side and pass described light guide and form.

11. the detection method of an optical touch control apparatus, described optical touch control apparatus comprises light source, light guide, imageing sensor and processing unit, described light guide has incidence surface, touch surface and exiting surface, be formed with a plurality of microstructures on described light guide inside and/or the described exiting surface, described detection method comprises the following step:

Utilize described light source luminous with the first brightness and the second brightness in turn;

Utilizing described imageing sensor to obtain from described light source with sampling frequency is incident to described light guide and is subject to described microstructure towards the reflection of described touch surface, the reflected light that penetrates from described exiting surface again, to produce the first picture frame corresponding to described the first brightness and to produce the second picture frame corresponding to described the second brightness;

Utilize described processing unit to calculate the difference diagram picture frame of described the first picture frame and described the second picture frame; With

Utilize described processing unit to come the decision operation state according to the comparative result of described difference diagram picture frame and two threshold values.

12. detection method according to claim 11 wherein when the eigenwert of described difference diagram picture frame during greater than first threshold and less than Second Threshold, is judged to be suspended state; When the described eigenwert of described difference diagram picture frame during greater than described Second Threshold, be judged to be contact condition.

13. detection method according to claim 12, wherein said eigenwert are maximal value and/or the mean value of maximum brightness value, average brightness value, filtering image frame.

14. according to claim 11, the described detection method of each claim in 12 or 13, wherein said Second Threshold is zero luminance or non-zero luminance.

15. detection method according to claim 11, the reflected light that wherein said exiting surface penetrates are that the scattered light of described microstructure reflection is through the object reflection of described touch surface side and pass described light guide and form.

16. the detection method of an optical touch control apparatus, described optical touch control apparatus comprises light source, light guide, imageing sensor and processing unit, described light guide has incidence surface, touch surface and exiting surface, be formed with a plurality of microstructures on described light guide inside and/or the described exiting surface, described detection method comprises the following step:

Utilize described light source luminous with the first brightness, the second brightness and the 3rd brightness in turn;

Utilizing described imageing sensor to obtain from described light source with sampling frequency is incident to described light guide and is subject to described microstructure towards the reflection of described touch surface, the reflected light that penetrates from described exiting surface again, to produce the first picture frame corresponding to described the first brightness, to produce the second picture frame and produce the 3rd picture frame corresponding to described the 3rd brightness corresponding to described the second brightness;

Utilize described processing unit to calculate the first difference diagram picture frame of described the first picture frame and described the 3rd picture frame, and calculate the second difference diagram picture frame of described the second picture frame and described the 3rd picture frame; With

Utilize described processing unit to come the decision operation state according to the comparative result of described the first difference diagram picture frame and described the second difference diagram picture frame and at least one threshold value.

17. detection method according to claim 16 wherein during less than Second Threshold, is judged to be suspended state greater than the eigenwert of first threshold and described the second difference diagram picture frame when the eigenwert of described the first difference diagram picture frame; When the described eigenwert of described the second difference diagram picture frame during greater than described Second Threshold, be judged to be contact condition, wherein said first threshold equals or is not equal to described Second Threshold.

18. detection method according to claim 17, wherein said eigenwert are maximal value and/or the mean value of maximum brightness value, average brightness value, filtering image frame.

19. according to claim 16, the described detection method of each claim in 17 or 18, wherein said the 3rd threshold value is zero luminance or non-zero luminance.

20. detection method according to claim 16, the reflected light that wherein said exiting surface penetrates are that the scattered light of described microstructure reflection is through the object reflection of described touch surface side and pass described light guide and form.

Images