CN102436329B - Infrared touch system based on liquid crystal light valves and optical lenses - Google Patents

Abstract

The invention discloses an infrared touch system based on a liquid crystal light valve and an optical lens, which includes a touch screen. Among the four edges of the touch screen, a plurality of infrared emitting diodes are respectively arranged at two adjacent edges, and a plurality of infrared emitting diodes are respectively arranged at the other two adjacent edges. There are a plurality of infrared receiving diodes, and a pair of liquid crystal light valves and an optical lens are sequentially arranged in front of the light emitting surface of each infrared emitting diode. The invention can effectively remove false touch points, can solve the problem that multi-touch point recognition requires multiple scanning times, and has the advantages of fast response, no blind spots and the like.

Description

An Infrared Touch System Based on Liquid Crystal Light Valve and Optical Lens

technical field

The present invention relates to the field of infrared touch screens, specifically an infrared touch system based on liquid crystal light valves and optical lenses.

Background technique

Infrared touch screen is a natural human-computer interaction device. With its naturalness and convenience, it is gradually becoming a very attractive new multimedia interactive device. The infrared touch screen has the characteristics of high light transmittance, long service life, and is not afraid of scratches, especially in large-size display solutions with high cost performance. There are two methods for early infrared touch screens to identify multiple touch points: time-sharing method and partition method. For the time-sharing method, it cannot be judged accurately when there are always two fingers touching at the same time; for the partition method, when there are many touch coordinates, more partitions are needed, and the number of scans also increases accordingly, which seriously affects the touch screen. The short response time limits the development of infrared multi-touch. Patent No. CN200920079315.4 discloses an infrared touch screen with a horizontally inclined double-layer infrared diode arrangement. The double-layer infrared diode structure increases the thickness of the touch screen, and the number of diodes to be arranged is too large, resulting in an excessively long scan period. , affecting response time. Patent No. CN201020256135.1 discloses a single-layer infrared diode multi-touch structure, which only adds a few pairs of infrared diodes at the corners of the touch screen, and there is a blind area for touch point recognition.

Contents of the invention

The purpose of the present invention is to provide an infrared touch system based on a liquid crystal light valve and an optical lens, so as to solve the problem that the infrared touch screen in the prior art requires multiple scans for multi-touch points and there is a blind area for touch point recognition.

In order to achieve the above object, the technical scheme adopted in the present invention is:

An infrared touch system based on a liquid crystal light valve and an optical lens, including a touch screen, is characterized in that: among the four edges of the touch screen, a plurality of infrared emitting diodes are respectively arranged at two adjacent edges, and a plurality of infrared emitting diodes are respectively arranged at the other two adjacent edges There are a plurality of infrared receiving diodes, and the infrared emitting diodes at one edge of the touch screen are facing the infrared receiving diodes at the opposite edge one by one. Each infrared emitting diode is respectively provided with the same central axis as the infrared emitting diode in front of the light emitting surface. A pair of liquid crystal light valves and an optical lens. The pair of liquid crystal light valves is composed of two liquid crystal light valves connected in a straight line and placed horizontally in front of the light emitting surface of the infrared emitting diode. Each liquid crystal light valve is centered on two liquid crystal light valves. The polarities are different and the switches are interlocked, and the positions of the liquid crystal light valves with the same polarity in the pair of liquid crystal light valves in front of the light-emitting surfaces of multiple infrared emitting diodes correspond to each other; , the negative polarity liquid crystal light valve is cut off, and the laser light emitted by each infrared emitting diode passes through the corresponding positive polarity liquid crystal light valve, and then passes through the corresponding optical lens, and then enters the opposite side and the same side is staggered by a certain distance The infrared receiving diodes form an infrared light grid composed of infrared light; when the liquid crystal light valve is centered and the negative polarity liquid crystal light valve is turned on, the positive polarity liquid crystal light valve is cut off, and the laser light emitted by each infrared emitting diode Pass through the corresponding negative polarity liquid crystal light valves, and then pass through the corresponding optical lenses, and then enter the infrared receiving diodes on the opposite side and the same side with a certain distance staggered to form another infrared light network composed of infrared light. grid.

The infrared touch system based on a liquid crystal light valve and an optical lens is characterized in that: the infrared emitting diodes and the infrared receiving diodes are all tombstone-shaped infrared diodes.

The infrared touch system based on liquid crystal light valves and optical lenses is characterized in that the widths of the two liquid crystal light valves in the pair of liquid crystal light valves in front of the light emitting surface of each infrared emitting diode are less than half of the width of the infrared emitting diode.

The above-mentioned infrared touch system based on liquid crystal light valve and optical lens is characterized in that the shape of the optical lens is columnar, and the infrared emitting diode is located at the focal plane of the optical lens.

The infrared touch system based on liquid crystal light valves and optical lenses is characterized in that: every eight pairs of liquid crystal light valves are produced as a group, and each liquid crystal light includes a positive polarity and a negative polarity liquid crystal light Valves and liquid crystal light valve pairs are connected together to improve the reusability of liquid crystal light valves when they are driven in a group of 8 commonly used infrared emitting tubes.

The infrared touch system based on liquid crystal light valves and optical lenses is characterized in that: each liquid crystal light valve is centered, and the connection between the two liquid crystal light valves is located on the central axis of the optical lens and the infrared emitting diode, and is also located On the main axis of the focal plane of the optical lens, the junction of the two liquid crystal light valves is shielded with a material that absorbs the emitted light wavelength.

The invention can effectively remove false touch points, can solve the problem that multi-touch point recognition requires multiple scanning times, and has the advantages of fast response, no blind spots and the like.

Description of drawings

Figure 1 is a schematic diagram of the overall structure of the present invention.

FIG. 2 is a schematic diagram of a tombstoning infrared diode of the present invention.

Fig. 3 is a schematic diagram of the appearance of the optical lens of the present invention.

Fig. 4 is the propagating light path figure of optical lens among the present invention.

Fig. 5 is a schematic diagram of the simulation results of the optical lens of the present invention in the case of oblique incident light on the focal plane.

Fig. 6 is a schematic diagram of the arrangement and distribution of the liquid crystal light valves of the present invention.

Fig. 7 is a diagram of the optical path transmission when the positive polarity liquid crystal light valve is turned on in the present invention.

Fig. 8 is a diagram of optical path transmission when the negative polarity liquid crystal light valve is turned on in the present invention.

Detailed ways

As shown in Figure 1. The touch screen of the present invention includes an infrared emitting diode 11, an infrared receiving diode 13, two pairs of liquid crystal light valves 12, an optical lens 14, and an opaque object 15. The two adjacent edges of the touch screen are covered with infrared emitting diodes, and the other two adjacent edges are covered with infrared receiving diodes. The infrared emitting diodes on one edge of the touch screen are directly opposite to the infrared receiving diodes on the opposite side. Closely arranged on the edge of the touch screen to form an orthogonal infrared array. A pair of liquid crystal light valves 12 consisting of two interlocked liquid crystal light valves with different polarity switches is placed in front of the infrared emitting diode to control the conduction and cutoff of infrared light at different positions of the optical lens at different times. In front of the pair of liquid crystal light valves, an optical lens matching the width of the pair of liquid crystal light valves is fixed, and the infrared emitting diode is located on the focal plane of the optical lens, so that the infrared light passing through the pair of liquid crystal light valves exits in parallel. The opaque object 15 is placed in the middle of the pair of liquid crystal light valves, so that the infrared light does not pass through the main axis of the optical lens, so that two groups of parallel lights are formed in time-sharing, that is, two groups of different infrared grids are formed at different times. Once a touch object blocks, it will block two groups of different optical paths in time, and more than two infrared receiving diodes cannot receive infrared light at different times. The coordinates of multi-touch can be calculated according to different occlusions. In the case of a large-size infrared touch screen, more infrared emission pairs are required. Using this method can reduce the scanning time and improve the response speed of multi-point touch.

In the case of no external voltage, the liquid crystal light valve cannot form a regular electric field between the films, and the liquid crystal molecules are in a disordered state. The effective refractive index does not match the refractive index of the polymer, and the incident light is strongly reflection. When an external voltage is applied, the optical axes of the liquid crystal particles are arranged perpendicular to the surface of the film, that is, in line with the direction of the electric field. Light does not scatter. In the present invention, the two liquid crystal light valves in front of each infrared emitting diode have different polarities, and are respectively turned on at different times to control the passage of light at different positions.

as shown in picture 2. The rear of the tombstone infrared diode is a cuboid, and the front is a hemispherical flat diode with a width of 3mm-5mm.

As shown in Figure 3. The optical lens is composed of many small optical lens units with the same structure and performance arranged linearly, one side is flat, and the other side is a periodically undulating curved surface. Each optical lens unit does not converge the light in the direction perpendicular to the arrangement direction, but in the arrangement direction, each optical lens unit is equivalent to a converging lens, which plays the role of focusing and imaging.

As shown in Figure 4. The infrared light passing through the liquid crystal light valve is regarded as a unit light, and placed on the focal plane of the optical lens, that is, the image is on the focal plane, so that any point on the image plane can become a parallel beam through the cylindrical lens. As shown in the figure, with point O as the center of the circle, for point y=0, it becomes a light beam propagating along the optical axis oo' after being refracted by the cylinder. With the optical axis oo' as the boundary, the thin parallel beam formed by the point y greater than 0 transmits information downward; the thin parallel beam formed by the point y<0 transmits information upward, and the width of the thin parallel beam is the optical lens unit The grid pitch p. The calculation formula of the angle δ of the parallel beam deviating from the optical axis yy is as follows, y is the position from the longitudinal axis of the origin, r is the radius of curvature of the grating plate, and n is the refractive index of the grating plate:

As shown in Figure 5. The point light source is located above the main axis of the focal plane, and its output light is parallel light deflected downward at a certain angle.

As shown in Figure 6. The infrared touch system based on liquid crystal light valves and optical lenses is characterized in that: every eight pairs of liquid crystal light valves are produced as a group, and each liquid crystal light includes a positive polarity and a negative polarity liquid crystal light Valves and liquid crystal light valve pairs are connected together to improve the reusability of liquid crystal light valves when they are driven in a group of 8 commonly used infrared emitting tubes.

As shown in Figure 7. Fig. 7 is a transmission diagram of the optical path when the positive polarity liquid crystal light valve is turned on. Assuming that two touch signals are detected, the coordinate positioning point of the infrared grid is obtained according to the calculation principle of the sides and corners of the triangle. Since the touch signals of two points can be combined to obtain four points A(m,a),B(n,a),C(m,b),D(n,b);

As shown in Figure 8. Fig. 8 is a transmission diagram of the optical path when the negative polarity liquid crystal light valve is turned on. It forms an inclination in a direction different from that shown in FIG. 7 . When Figure 7 detects four touch coordinates of A, B, C, and D, Figure 8 blocks light from different optical paths, and four points A, D, E, and F can be obtained through coordinate calculation, two of which are the same as those in Figure 7 The coordinates are the same, while the other two are different. According to the analysis of the two sets of coordinates, false touch points can be excluded, and the multi-touch response to the control interface can be performed through ordinary touch gesture recognition.

The working process of the present invention is as follows:

a. Drive the infrared emitting diodes one by one, and give the liquid crystal light valves a positive level, so that the positive polarity liquid crystal light valves are in the conduction state, the infrared light passes through the positive polarity liquid crystal light valves, and the negative polarity liquid crystal light valves are cut off. That is to say, a group of liquid crystal light valves with the same polarity in front of the infrared emitting tube is controlled to be turned on and the other group is turned off. the

b. When the positive polarity liquid crystal light valve is turned on, a cross infrared grid is formed on the entire touch panel; once a touch occurs, the infrared rays are blocked, and a set of touch signals can be obtained.

c. When the negative polarity liquid crystal light valve is turned on, the positive polarity liquid crystal light valve is turned off, forming an infrared grid with a different direction from that when the positive polarity is turned on; another set of touch signals is obtained.

d. Obtain two groups of touch coordinates through the coordinate solution of the two groups of touch signals; if there is only one touch point obtained by the two groups of touch signals, then it is a single touch; if multiple touch points are detected, Then analyze the combination of the touch coordinates of the first group and the second group, remove the false touch points, and obtain the real touch points.

e. From the touch points obtained above, according to the gesture recognition, determine the multi-touch gesture, realize the gesture response to the user, and perform multi-point control on the touch interface.

Claims (5)

1. infrared touch system based on liquid crystal light valve and optical lens, comprise touch-screen, it is characterized in that: in touch-screen four edges, limit, two adjacent edges are furnished with respectively a plurality of infrared-emitting diodes, other two adjacent edges are furnished with respectively a plurality of infrared receiving diodes, the infrared-emitting diode of one of them edge of touch-screen is one by one over against the infrared receiving diode of its offside edge, each infrared-emitting diode exiting surface the place ahead is disposed with respectively and the infrared-emitting diode liquid crystal light valve pair of central shaft altogether, optical lens, described liquid crystal light valve is to being connected as one by two words and horizontal liquid crystal light valve in infrared-emitting diode exiting surface the place ahead consists of, each liquid crystal light valve centering, two liquid crystal light valve junctions are positioned at optical lens, on the central shaft of infrared-emitting diode, also be positioned on the main shaft of optical lens focal plane, block with the material that absorbs wavelength of transmitted light two liquid crystal light valve junctions, two liquid crystal light valve polarity differences of each liquid crystal light valve centering and switch interlock, the liquid crystal light valve position of the liquid crystal light valve Middle Phase same polarity in a plurality of infrared-emitting diode exiting surfaces the place aheads is corresponding respectively, when liquid crystal light valve centering, during the liquid crystal light valve conducting of positive polarity, the liquid crystal light valve cut-off of negative polarity, each infrared-emitting diode emitting laser passes the liquid crystal light valve of each self-corresponding positive polarity, pass again and be incident to stagger over against the same side, the position infrared receiving diode of certain distance of offside after each self-corresponding optical lens, form an infrared light grid that is consisted of by infrared light, when liquid crystal light valve centering, during the liquid crystal light valve conducting of negative polarity, the liquid crystal light valve cut-off of positive polarity, each infrared-emitting diode emitting laser passes the liquid crystal light valve of each self-corresponding negative polarity, pass again be incident to after each self-corresponding optical lens offside over against the position the stagger infrared receiving diode of certain distance of another homonymy, form the infrared light grid that another is made of infrared light.

2. a kind of infrared touch system based on liquid crystal light valve and optical lens according to claim 1, it is characterized in that: described infrared-emitting diode, infrared receiving diode are the infrared diode of gravestone shape.

3. a kind of infrared touch system based on liquid crystal light valve and optical lens according to claim 1 is characterized in that: the width of two liquid crystal light valves of liquid crystal light valve centering in each infrared-emitting diode exiting surface the place ahead all less than the infrared-emitting diode width half.

4. a kind of infrared touch system based on liquid crystal light valve and optical lens according to claim 1, it is characterized in that: optical lens shape is column, and infrared-emitting diode is positioned at the optical lens focal plane position.

5. a kind of infrared touch system based on liquid crystal light valve and optical lens according to claim 1 is characterized in that: every eight liquid crystal light valves are to being a row, and row and row link together, to improve the reusing of liquid crystal light valve.

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