TWI447622B - Optical touchpad apparatus - Google Patents

Description

Optical touch device

The present invention relates to a touch device, and more particularly to an optical touch device.

In today's market of consumer electronics products, mobile phones, digital audio and video players, desktop computers, notebook computers, personal digital assistants, satellite navigation systems, and other electronic products with liquid crystal displays all use touch devices. The trend of human-machine data communication interface is to save the space occupied by peripherals such as keyboard and mouse, so as to achieve the purpose of light and thin product structure.

At present, the optical touch device usually has two or more infrared light sources installed outside the liquid crystal display, and two or more infrared light receiving tubes or image capturing modules that rely on infrared light imaging, and the infrared light source. Infrared light is emitted on the surface of the liquid crystal display to form an infrared light net. When the consumer touches the liquid crystal display with a finger or a stylus, the infrared light net is also touched, so that the infrared light is blocked or The optical path changes, and the change is reflected on the infrared light receiving tube or the image capturing module, that is, the light is not received or the image is changed, and the coordinates of the touch point are obtained by calculation or comparison, thereby generating a touch response. .

However, the above method has the following disadvantages: First, an infrared light source must be installed, because infrared light emitted by the infrared light source is used as the detection light, so an infrared light source must be installed, which will increase the cost of the optical touch device; Because it is necessary to determine the coordinates of the touch point by comparing the images before and after the touch, because the touch point needs to be obtained. Coordinates, so the algorithm is complex; again, because of the need to install infrared light receiving tubes or infrared sensitive image capturing modules in two dimensions, it also increases the cost of the optical touch device.

In view of this, it is necessary to provide an optical touch device that does not require an infrared light source, has a simple algorithm and is low in cost.

An optical touch device includes a liquid crystal display module, a stress sensing component, and an image capturing module. The liquid crystal display module has a light emitting surface, and the emitted light is linearly polarized light, and the stress sensing component is located at the light emitting device. In front of the surface, the stress sensing component is transparent and anisotropic after being pressed by an external force, and the image capturing module has a polarizing plate whose polarization direction is orthogonal to the polarization direction of the linearly polarized light, and the linearly polarized light After the stress sensing component pressed by the external force, the image capturing module generates an interference pattern to determine the coordinates of the position pressed by the external force.

Compared with the prior art, the optical touch device provided by the present invention utilizes the characteristic that the light emitted by the liquid crystal display module is linearly polarized light, and the polarization sensing interference pattern is formed by providing the stress sensing component and the polarizing plate, thereby calculating the external force. The coordinates of the position of the oppression, the structure and calculation method are simple, and the infrared light source is not needed, and the cost is low.

1, 2, 3‧‧‧ optical touch devices

14, 24‧‧‧Image capture module

101,300‧‧‧LCD module

102, 202, 302‧‧‧ Stress sensing components

140‧‧‧Lens module

142‧‧‧Image Sensor

144‧‧‧Polarizer

22‧‧‧Slots

25‧‧‧Support rod

201‧‧‧ upper side

204‧‧‧ frame

40‧‧‧Liquid layer

41‧‧‧First stress sensor

42‧‧‧Second stress sensor

1 is a schematic structural view of an optical touch device according to a first embodiment of the present invention.

2 is a schematic structural view of an image capturing module of the optical touch device shown in FIG.

3 is a cross-sectional view showing the structure of a liquid crystal display panel of the optical touch device shown in FIG. 1.

4 is a perspective structural view of a liquid crystal display panel of an optical touch device according to a second embodiment of the present invention.

5 is a cross-sectional view showing the structure of a liquid crystal display panel of an optical touch device according to a third embodiment of the present invention.

The invention will now be described in further detail with reference to the accompanying drawings.

Referring to FIG. 1 , FIG. 2 and FIG. 3 , the optical touch device 1 of the first embodiment of the present invention includes a liquid crystal display module 101 , a stress sensing component 102 , and an image capturing module 14 .

The liquid crystal display module 101 is a liquid crystal display panel. The stress sensing component 102 is a sheet made of an isotropic light transmissive material, such as isotropic glass or plastic, and has a thickness that is thin but not durable, and is packaged together with the liquid crystal display module 101. It is disposed in front of the liquid crystal display module 101, that is, the light exiting portion of the liquid crystal display module 101. The size of the stress sensing component 102 is the same as the size of the light emitting surface of the liquid crystal display module 101. Since the liquid crystal display module 101 itself includes two polarizing plates (not shown), the emitted light is linearly polarized light.

The stress sensing member 102 is characterized by anisotropy under the action of external force compression, and birefringence occurs when polarized light is incident.

The stress sensing component 102 can also function to protect the liquid crystal display module 101.

The image capturing module 14 includes a lens module 140 , an image sensor 142 , and a polarizing plate 144 . The polarization direction of the polarizing plate 144 is orthogonal to the polarization direction of the outgoing light of the liquid crystal display module 101. The image capturing module 14 is disposed above the liquid crystal display module 101. For example, the image capturing module 14 can be located at a certain corner of the liquid crystal display module 101. In summary, the field of view of the image capturing module 14 covers the entire liquid crystal. The light exit surface of the module 10 is displayed to receive a polarization interference pattern.

When the liquid crystal display module 101 is in a bright state, the image capturing module 14 is basically Light from the liquid crystal display module 101 is not received. The polarization direction of the polarizing plate 144 of the image capturing module 14 is orthogonal to the polarization direction of the light of the liquid crystal display module 101. Therefore, the polarizing plate 144 blocks the light from entering the lens module 140 and the image sensor. 142. Considering that light from other objects may be ingested by the lens module 140, the image capturing module 14 is in an extinction state with respect to the liquid crystal display module 101, but the field of view is not It is dark, just in the darkest state.

When the stress sensing component 102 is touched by a finger or other object, the stress sensing component 102 is stressed by the position touched by the external force, and the light from the liquid crystal display module 101 is birefringent, and the two vibration directions are different. The light rays, the two beams having different vibration directions pass through the polarizing plate 144, and then interfere with the polarized light, thereby forming an interference pattern in the field of view of the image capturing module 14, due to the additional phase between the two beams having different vibration directions. The difference varies with the stress distribution of the stress sensing component 102. Therefore, the interference pattern also reflects the stress distribution information of the stress sensing component 102. Moreover, the more concentrated the stress, the denser the interference fringe, the brighter the brightness, and the stress. The most concentrated position is the touch position, so it can be said that the highlight area is the touch position.

The field of view of the image capturing module 14 is originally in the darkest state. Now, due to the polarization state of the light emitted by the liquid crystal display module 101, and the polarization interference occurs, the field of view becomes brighter, and more importantly, Interference fringes with information on stress distribution were observed.

Similarly, for the continuously moving touch track, the image capture module 14 can also make corresponding records. The touch trajectory of continuous movement is reflected on the interference pattern, that is, the interference pattern is continuously transformed, but as long as the continuous movement trajectory of the bright point is recorded, External interference fringes can be used as an auxiliary analysis to further accurately calculate the coordinates of the touch position.

This way of determining the coordinates of the touch position by observing the interference pattern is intuitive and highly sensitive. Since the coordinates of the touch position can be calculated by sensing the interference pattern, an image capturing module that covers the light emitting surface of the liquid crystal display module 101 in one field of view is sufficient, and it is not necessary to use multiple.

The optical touch device 1 does not require other detection light, such as infrared light, and only uses the light emitted from the liquid crystal display module 101, and does not require multiple image capture modules, so the cost is low.

Referring to FIG. 4, the optical touch device 2 of the second embodiment of the present invention has substantially the same structure as the optical touch device 1, and includes a liquid crystal display module (not shown), a stress sensing component 202, and an image capturing module. In the group 24, the image capturing module 24 is supported by the support rod 25 in front of the liquid crystal display module and faces the light emitting surface thereof, except that the stress sensing component 202 is assembled differently.

The stress sensing component 202 is a sheet made of an isotropic light transmissive material, such as isotropic glass or plastic, having the same size as the light emitting surface of the liquid crystal display module, but with the stress provided by the first embodiment. The sensing component 102 is different and is not packaged with the liquid crystal display module.

The optical touch device 2 has a frame 204 , and the liquid crystal display module and the stress sensing component 202 are housed in the frame 204 . In particular, the upper side 201 of the frame 204 is provided with a slot 22, so that the stress sensing component 202 can be inserted along the slot 22 and cover the light emitting surface of the entire liquid crystal display module. This design facilitates the replacement of the stress sensing component 202. The slot 22 has an elongated opening shape, and the opening width is slightly larger than the stress sensing component. The thickness of 202 is for insertion.

Of course, the narrow opening 22 can also be disposed on the left side or the right side or the lower side of the frame. Other manners of providing the stress sensing component 202 may be used, for example, the stress sensing component 202 is pasted on the frame 204. For easy replacement.

The structure of the other portions is the same as that of the optical touch device 1 of the first embodiment of the present invention.

Referring to FIG. 5 , the optical touch device 3 of the third embodiment of the present invention has substantially the same structure as the optical touch device 1 , and includes a liquid crystal display module 300 , a stress sensing component 302 , and an image capturing module ( Not shown), except that the structure of the stress sensing member 302 is different.

The stress sensing component 302 includes a first stress sensing sheet 41 and a second stress sensing sheet 42 and a liquid crystal layer 40 encapsulated between the first stress sensing sheet 41 and the second stress sensing sheet 42. When the first stress sensing sheet 41 is close to the light emitting surface of the liquid crystal display module 300, the second stress sensing sheet 42 is away from the light emitting surface. The size of the stress sensing component 302 is the same as the size of the light emitting surface of the liquid crystal display module 300.

The first stress sensing sheet 41 and the second stress sensing sheet 42 are respectively made of two isotropic light transmissive materials, such as isotropic glass or plastic, and the materials of the two stress sensing sheets may be different, but The same material is preferred.

The stress sensing component 302 can be packaged and fixed on the light emitting surface of the liquid crystal display module 300 together with the liquid crystal display module 300, or can be separately disposed on the light emitting surface of the liquid crystal display module 300 for replacement.

Since the liquid crystal layer 40 is very sensitive to the reaction of the pressure, it can react more accurately and quickly to the external force, causing stress inside the stress sensing part 302 to destroy the polarization state of the outgoing light which is originally linearly polarized light. Forming a polarization interference pattern purpose.

The optical touch device provided by the invention can also be used as a human-machine data communication interface of an electronic device such as a mobile phone, a digital video player, a desktop computer, a notebook computer, a personal digital assistant, a satellite navigation system, etc., and the cost is low, and The calculation process of the touch point coordinates is simple and intuitive.

1‧‧‧Optical touch device

14‧‧‧Image capture module

101‧‧‧LCD module

102‧‧‧stress sensing components

Claims (7)

An optical touch device is improved in that it comprises a liquid crystal display module, a stress sensing component and an image capturing module, wherein the liquid crystal display module has a light emitting surface, and the emitted light is linearly polarized light, and the stress sensing The component is located in front of the light-emitting surface, and the stress-sensing component is transparent and is anisotropic after being pressed by an external force. The image capturing module has a polarizing plate, and the polarization direction of the polarizing plate is orthogonal to the polarization direction of the linearly polarized light. The linearly polarized light passes through the stress sensing component that is pressed by the external force, and then the interference pattern is generated by the image capturing module to determine the coordinates of the position pressed by the external force. The optical touch device of claim 1, wherein the stress sensing component is made of isotropic glass or plastic, and the size of the stress sensing component and the light emitting surface of the liquid crystal display module are The same size. The optical touch device of claim 1, wherein the stress sensing component is packaged with the liquid crystal display module. The optical touch device of claim 1, wherein the optical touch device further comprises a frame, the frame is provided with a slot, and the liquid crystal display module and the stress sensing component are received in the frame The stress sensing component is inserted and removed from the slot. The optical touch device of claim 1, wherein the stress sensing component comprises a first stress sensing sheet, a second stress sensing sheet, and the first stress sensing sheet and the second package The liquid crystal layer between the stress sensing sheets. The optical touch device of claim 5, wherein the optical touch device further comprises a frame, the frame is provided with a slot, and the liquid crystal display module and the stress sensing component are received in the frame The stress sensing component is inserted and removed from the slot. The optical touch device of claim 1, wherein the image capturing module further comprises The lens module and the image sensor are located in front of the lens module.