CN202167000U

CN202167000U - Optical touch screen and display device

Info

Publication number: CN202167000U
Application number: CN2011200923901U
Authority: CN
Inventors: 唐德明; 毛剑宏
Original assignee: Lexvu Opto Microelectronics Technology Shanghai Co Ltd
Current assignee: Lexvu Opto Microelectronics Technology Shanghai Co Ltd
Priority date: 2011-03-31
Filing date: 2011-03-31
Publication date: 2012-03-14
Anticipated expiration: 2021-03-31

Abstract

The utility model discloses an optical touch screen and a display device including the optical touch screen. The optical touch screen comprises a backlight source, a detecting base plate and an optical element, wherein the backlight source is used for emitting measuring light which is emitted to the direction of the detecting base plate; the detecting base plate towards one side of the backlight source is provided with a plurality of photosensitive elements which are arranged in the form of a matrix; the optical element is arranged on one side, which deviates from the backlight source, of the detecting plate; and one side surface, which deviates from the detecting base plate, of the optical element is a touch surface; a touch piece which contacts with the touch surface forms a first image on detecting surfaces of photosensitive elements by the optical element; an interference light source which enters at a distance from the touch surface forms a second image on the detecting surfaces of the photosensitive elements by the optical element; and the definition of the first image is bigger than that of the second image.

Description

Optical touch screen and display device

Technical Field

The utility model relates to an optical instrument technical field especially relates to an optical touch screen, display device.

Background

With the continuous development and progress of science and technology, various display systems are widely applied to daily life. With the increasing improvement of living standard, people no longer satisfy the information provided by a passive receiving display system, a series of products such as a touch liquid crystal display screen and an IPAD are developed in recent years, and the display systems of the products are provided with the touch screen, so that the functions of information display and information input can be integrated together, and a convenient and fast man-machine interaction mode is formed.

A touch screen integrated on a display system is generally used to detect a touched position of a touching member (e.g., a finger or an electronic pen) on the touch screen. Touch screens include resistive, capacitive, surface acoustic wave, and the like, depending on the detection principle.

An optical touch screen has also been developed in the prior art, and a schematic diagram of an embodiment of the optical touch screen in the prior art is shown with reference to fig. 1. The optical touch screen includes: a glass substrate 10; the photosensitive array 11 is arranged on the lower surface of the glass substrate 10, and the photosensitive array 11 comprises a plurality of photosensitive elements arranged in a matrix form; and a reflective substrate 16 positioned below the photosensitive element, wherein the bottom of the reflective substrate 16 is provided with a plurality of reflective protrusions 15 toward the glass substrate 10, and one side of the reflective substrate 16 is provided with a light source 14. The detection process of the optical touch screen is as follows: a finger (or an electronic pen) 12 touches the upper surface of the glass substrate 10, measuring light emitted by a light source 14 is reflected by a reflecting bulge 15 and then projected to the tip of the finger 12, the measuring light is reflected at the tip of the finger 12, then the reflected light is projected onto a photosensitive array 11 and detected by a photosensitive element, and finally the position of a finger tip touch point of the finger 12 is obtained according to the position of the photosensitive element which detects the reflected light in the photosensitive array 11.

However, the optical touch screen in the prior art is easily affected by an interference light source, and after parallel light beams such as sunlight enter the optical touch screen, a strong interference signal is generated in the photosensitive element, which affects the accuracy of the optical touch screen in detecting the touch position.

Please refer to chinese patent publication No. CN101266346C for more optical touch screens.

SUMMERY OF THE UTILITY MODEL

The utility model provides a problem provide a higher optical touch screen of precision.

In order to solve the above problem, the utility model provides an optical touch screen, include: the device comprises a backlight source, a detection substrate positioned on the backlight source and an optical element positioned on the detection substrate, wherein the upper surface of the optical element is a touch surface; the backlight source is used for emitting measuring light which is emitted to the direction of the detection substrate; the detection substrate is provided with a plurality of photosensitive elements arranged in a matrix form on one side, facing the backlight source, of the detection substrate; the optical element is positioned on one side, away from the backlight source, of the detection substrate, the surface, away from the detection substrate, of the optical element is a touch surface, and a touch piece, which is in contact with the touch surface and touches the optical touch screen, forms a first image on a detection surface of the photosensitive element through the optical element; an interference light source incident at a certain distance from the touch surface forms a second image on the detection surface of the photosensitive element through the optical element; the definition of the first image is greater than the definition of the second image.

Optical element includes a plurality of lens and the printing opacity film that just are the matrix arrangement that are located the coplanar, lens set up in the printing opacity film.

The distance between the touch surface of the optical element and the lens is D, the distance between the lens and the detection surface of the photosensitive element is D, the focal length of the lens is f, and the relation that D is larger than f and smaller than 2f and D is larger than 2f is satisfied.

The distance between the touch surface of the optical element and the lens is D, the distance between the lens and the detection surface of the photosensitive element is D, the focal length of the lens is f, and the relation that 1/f is 1/D +1/D is satisfied.

D is 1.5f and D is 3 f.

The lens is a Fresnel lens.

The focal length f of the lens is within the range of 0.1-3 mm.

The distance measuring device further comprises a calculating unit, wherein the calculating unit is used for calculating the distance from the touch piece to the touch surface according to the size of a first image formed by the detection surface of the touch piece on the photosensitive element and an imaging formula based on the object height/image height and the object distance/image distance.

The photosensitive elements are arranged in an M multiplied by N matrix form, the lenses are arranged in an M multiplied by N matrix form, the relation that M is less than or equal to M and N is less than or equal to N is met, and M, N, M and N are natural numbers.

The utility model also provides an include optical touch screen's display device.

Compared with the prior art, the utility model has the advantages of it is following:

1. the utility model provides an optical touch screen filters the interference of disturbing light to detecting the touch position, has improved measurement accuracy;

2. the distance of the finger from the touch surface can be obtained from the size of the image measured by the light sensitive elements.

Drawings

FIG. 1 is a schematic diagram of one embodiment of a prior art optical touch screen;

fig. 2 is a schematic diagram of an embodiment of an optical touch screen according to the present invention;

FIG. 3 is a schematic diagram of the optical path of the optical touch screen of FIG. 2;

FIG. 4 is a schematic diagram of the optical path of the optical touch screen of FIG. 2 for interference;

fig. 5 is a schematic diagram of another embodiment of the optical touch screen of the present invention.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.

Referring to fig. 2, a schematic diagram of an embodiment of an optical touch screen according to the present invention is shown. The optical touch screen 100 includes a backlight 120, a detection substrate 110 disposed on the backlight 120, and an optical element 130 disposed on the detection substrate 110, wherein,

the backlight 120 includes a reflective substrate 106 and light sources 104. The reflective substrate 106 can reflect the light emitted from the light source 104 toward the detection substrate 110 to form measurement light, so as to detect the touch position when a finger touches the optical touch screen. Specifically, the reflective substrate 106 is a flat glass, the light source 104 is disposed on one side of the flat glass, the light source 104 may be an LED group configured to emit light of three colors of red, green, and blue at different times, a surface (an upper surface in the drawing) of the flat glass facing the detection substrate 110 may transmit the light emitted by the light source 104, a surface (a lower surface in the drawing) of the flat glass facing away from the detection substrate is opaque, and a plurality of reflective protrusions 105 are further disposed on the lower surface, and the reflective protrusions 105 may reflect the light projected onto the reflective protrusions 105 toward the detection substrate, so as to form measurement light.

In other embodiments, the backlight 120 may be of other structures, and may emit the measuring light toward the detection substrate, for example, a light source directly emitting the measuring light toward the detection substrate 110, or a light source reflecting or refracting the measuring light multiple times to emit the measuring light toward the detection substrate.

The detecting substrate 110 includes a transparent substrate 101, and a photosensitive array 102 disposed on a surface (lower surface in the figure) of the transparent substrate 101 facing the backlight 120. The photosensitive array 102 includes a plurality of photosensitive elements arranged in a matrix on a surface (a lower surface in the drawing) of the light-transmitting substrate 101 on a side facing the backlight 120, and the photosensitive elements are disposed on the lower surface of the light-transmitting substrate 101 with a detection surface facing the light-transmitting substrate 101. In particular, the photosensitive element is an imageable optical element, for example, the photosensitive element is a Charge-coupled Device (CCD). Specifically, the transparent substrate 101 is a flat glass.

The optical element 130 includes a transparent film 103, and a plurality of lenses disposed in the transparent film 103 and located in the same plane, a side surface (in the figure, an upper surface) of the transparent film 103 facing away from the detection substrate 110 is a touch surface of the optical touch screen, and the lenses are arranged in a matrix in the transparent film 103 to form a lens array 107.

In another embodiment, the optical element 130 may also be a light-transmissive film, a plurality of lens groups disposed in the light-transmissive film and located in the same plane, or other focusing optics, and the lens groups or other focusing optics may function to image the touch member touching the surface onto the detection surface of the photosensitive array 102.

The above embodiments do not constitute a specific limitation to the above optical elements and any configuration known to those skilled in the art that can function to image a touch element of a touch surface onto a detection surface of a photosensitive array is within the scope of the present invention.

The optical element 130 may cause a touching member, i.e. a finger 108, touching the upper surface of the light-transmissive film 103 to form a first image on the detection surface of the light-sensitive element, while the optical element 130 may cause an interfering light source (e.g. the sun or parallel light similar to the sun) incident at a distance from the touch surface to form a second image in the detection surface of the light-sensitive element.

The photosensitive element is used to convert the image into a signal, for example, the signal is an electrical signal, but the invention is not limited thereto.

Because the optical element 130 can make the definition of the first image greater than that of the second image, the photosensitive element has a detection threshold, and because the definition of the second image is smaller than the detection threshold, and simultaneously because the definition of the first image formed by the finger is larger than the detection threshold, the photosensitive element does not detect the information of the second image formed by the sunlight during detection, so as to filter the interference signal of the sunlight, and further avoid the interference of the sunlight (or parallel light similar to the sunlight) to the detection of the touch position, thereby improving the measurement accuracy of the touch position.

The technical solution of the present invention will be further described below with reference to the specific embodiment of the optical element and the imaging optical path of the optical element to the finger and the sunlight. In the following embodiments, the interference light source is illustrated as the solar light.

Referring to fig. 3, an imaging optical path of an embodiment of the optical element shown in fig. 2 to sunlight is shown. The optical elements in this embodiment include a plurality of lenses 203 having a focal length f; the lens 203 is a short focal length lens, that is, f is small. If the distance from the lens 203 to the detection surface 204 of the photosensitive element is D and the distance from the upper surface of the transparent film to the lens 203 is D, the relationship that D is greater than 2f and D is greater than f and less than 2f is satisfied.

With 201 representing the sun and the distance between the sun 201 and the lens 203 being denoted as L, since the sun is very far from the lens 203, then L is satisfied to be much greater than 2f, according to the imaging formula:

1/f＝1/u+1/v；

where f is the focal length, u is the object distance, and v is the image distance. In the embodiment, L is an object distance, that is, 1/f is 1/L +1/v, and since the object distance L is much larger than 2f, the image distance v is larger than f but approximately equal to f, that is, after sunlight passes through the lens 203, the sunlight is imaged at a position between f and 2f and close to f.

In the embodiment, the distance D between the detection surface 204 of the photosensitive element and the lens 203 is greater than 2f, so that the detection surface 204 of the photosensitive element is farther from the imaging position of the sun, and therefore the second image formed by the sun at the detection surface 204 of the photosensitive element is a blurred image.

Referring to fig. 4, the optical path of the finger imaged by the optical element of fig. 3 is shown. Since the distance from the upper surface of the transparent film to the lens 203 is d, when the finger 206 touches the upper surface of the transparent film, the distance between the finger 206 and the lens 203 is d, and since d is greater than f and less than 2f, according to the imaging formula:

1/f＝1/u+1/v；

where f is the focal length, u is the object distance, and v is the image distance. In the present embodiment, the distance d between the finger 206 and the lens 203 is an object distance, that is, 1/f is 1/d +1/v, and since the object distance d is greater than f and less than 2f, the image distance v is greater than 2f, that is, after the finger 206 passes through the lens 203, an image is formed at a position greater than 2 f.

In the present embodiment, since the distance D between the detection surface 204 of the photosensitive element and the lens 203 is greater than 2f, the finger imaging position is closer to the detection surface 204 of the photosensitive element, and therefore, the first image formed on the detection surface 204 of the photosensitive element by the finger 206 is clearer than the second image formed on the detection surface 204 of the photosensitive element by the sun.

Because the definition of the second image formed by the sunlight on the detection surface 204 of the photosensitive element is small, the photosensitive element cannot detect the signal formed by the sun, and then the signal formed by the sunlight can be filtered, so that the interference of the sunlight (or parallel light similar to the sunlight) to the detection of the touch position is avoided, and the measurement precision of the touch position is improved.

In a preferred embodiment, the distance between the finger and the lens 203 (i.e. the distance between the upper surface of the transparent film and the lens 203) is D, the distance between the lens 203 and the detection surface 204 of the photosensitive element is D, and the focal length f of the lens 203 satisfies the imaging formula, i.e. 1/f is 1/D + 1/D; that is to say, the detection surface 204 of the photosensitive element is located at the position where the finger is imaged, which makes the image of the finger detected by the detection surface 204 of the photosensitive element be the clearest and have a large difference from the definition of the image formed by the sunlight on the detection surface of the photosensitive element, so as to better filter the signal generated by the sunlight on the photosensitive element.

Specifically, the distance D between the upper surface of the transparent film and the lens 203 is 1.5f, and the distance D between the lens 203 and the detection surface 204 of the photosensitive element is 3f, so that the imaging formula is satisfied, that is, 1/f is 1/1.5f +1/3f, and when a finger touches the upper surface of the transparent film, a clear image is formed on the detection surface 204 of the photosensitive element.

With continued reference to fig. 2, the plurality of lenses in the light transmissive array 107 are arranged in an M × N matrix and the light sensitive elements are arranged in an M × N matrix, such that M is less than or equal to M; and N is less than or equal to N, i.e. the density of the light sensitive elements is greater than the density of the lenses in both directions of the matrix, so that the light sensitive elements detect the image formed by the lenses well, M, N, M and N being natural numbers.

Specifically, the lens 203 is a fresnel lens, the fresnel lens is a sheet formed by injecting and pressing a polyolefin material, and generally, the focal length of the fresnel lens is relatively small and ranges from 0.1mm to 3 mm. A plurality of fresnel lenses may be formed in the light-transmissive optical film by embossing (imparting) to form the optical element. In practical applications, the distance D from the upper surface of the transparent film to the lens 203 and the distance D from the lens 203 to the detection surface 204 of the photosensitive element can be determined according to the value of the focal length f of the lens 203.

Referring to fig. 5, a schematic diagram of another embodiment of an optical touch screen of the present invention is shown, the optical touch screen including a backlight (not shown); the detection substrate 320 is positioned on the backlight source, the detection substrate 320 comprises a light-transmitting substrate 303 and a plurality of photosensitive elements 304 positioned on one surface of the light-transmitting substrate 303, which faces the backlight source, the plurality of photosensitive elements 304 are arranged in a matrix form, and the detection surface of each photosensitive element 304 faces the light-transmitting substrate 303; the optical touch screen further comprises an optical element 330 disposed on the detection substrate 320, wherein the optical element 330 comprises a transparent film 306 and a plurality of lenses 305 disposed in the transparent film 306, and the plurality of lenses 305 are arranged in a matrix in the transparent film 306 to form a lens array. The lens array can image the finger 301, and in this embodiment, the image plane imaged when the finger 301 touches the upper surface of the transparent film 306 is coplanar with the detection plane of the photosensitive element 304, but the present invention is not limited thereto.

The definition of the second image formed by the sunlight on the detection surface of the photosensitive element 304 through the optical element is low, and the photosensitive element 304 cannot detect the signal of the second image, so that the influence of the sunlight on the finger position detection is avoided.

In addition, the optical touch screen further includes a calculating unit (not shown), which is connected to the photosensitive element and can calculate the distance between the finger 301 and the upper surface of the optical element, that is, the distance from the touch surface, according to the size of the image formed by the finger 301 detected by the photosensitive element.

The principle of calculating the distance between the finger 301 and the lens 305 according to the size of the image by the calculating unit will be described in detail below with reference to fig. 5. In the present embodiment, since the size of the finger 301 is not changed and the distance between the lens 305 and the photosensitive element 304 is not changed, the object height and the image distance are both constant values, so that the image height is inversely proportional to the object distance, as shown in fig. 5, when the distance between the finger 301 and the lens 305 is d1, since d1 is large, the measurement light emitted from the backlight is reflected when the measurement light is transmitted to the finger 301, and the reflected light cannot be imaged on the photosensitive element 304 any more, so that there is no image corresponding to the finger 301 in the image a1 in the photosensitive element 304; when the finger 301 gradually approaches the lens 305 and is at a distance d2 from the lens 305, since d2 is smaller than d1, the image a2 formed in the photosensitive element 304 includes an image of a part of the finger 301, and the image of the finger 301 in the image a2 is crescent-shaped (i.e., an image formed by the tip of the finger), and is smaller in size; when the finger 301 gradually approaches the lens 305 again and is at a distance d3 from the lens 305, d3 is smaller than d2, and the image A3 formed in the photosensitive element 304 includes a complete image of the finger 301; when the finger 301 approaches the lens 305 and touches the upper surface of the lens 305, the distance d4 between the finger 301 and the lens 305, the image a4 formed in the photosensitive element 304 includes the image of the finger 301 intact, and the image of the finger 301 in a4 is larger than the image of the finger 301 in A3.

The size of the finger 301 is not changed (i.e. the object height is a fixed value), the distance between the lens 305 and the photosensitive element 304 is not changed (i.e. the image distance is a fixed value), the relative size (object distance) of the distance between the finger 301 and the lens 305 is obtained according to the imaging relation of the object height/image height being the object distance/image distance and the size (image height) of the image of the finger 301 detected by the photosensitive element 304, and since the distance between the lens 305 and the upper surface (touch surface) of the transparent film is fixed, the distance between the lens 305 and the touch surface can be further subtracted by the calculation unit in the photosensitive element 304, so as to obtain the distance between the finger 301 and the touch surface.

Therefore, it can be seen that the optical touch screen of this embodiment not only can obtain the position of finger in the touch surface, can also obtain the distance of finger distance touch surface, and then obtains the three-dimensional position of finger touch position, thereby makes the utility model discloses an optical touch screen is applicable to 3D display device.

In summary, the optical touch screen provided by the utility model has higher precision for detecting the touch position; the touch position of the finger can be measured in the three-dimensional direction, and the method is further suitable for a 3D display device.

In the above embodiment, the touch member of the optical touch screen is exemplified by a finger, but the present invention is not limited thereto, and may be other touch members such as an electronic pen.

Accordingly, the present invention further provides a display device including the optical touch screen, wherein the display device may be a liquid crystal display device or an Organic Light-Emitting Diode (OLED) display device.

Although the present invention has been disclosed in the preferred embodiments, it is not intended to limit the present invention, and any person skilled in the art can use the above-mentioned method and technical contents to make possible changes and modifications to the technical solution of the present invention without departing from the spirit and scope of the present invention, therefore, any simple modification, equivalent changes and modifications made to the above embodiments by the technical substance of the present invention all belong to the protection scope of the technical solution of the present invention.

Claims

1. An optical touch screen, comprising: a backlight, a detection substrate and an optical element,

wherein,

a backlight source for emitting measurement light directed toward the detection substrate;

the detection substrate is provided with a plurality of photosensitive elements arranged in a matrix form on one side facing the backlight source;

an optical element which is positioned on one side of the detection substrate, which is far away from the backlight source, and the surface of one side of the optical element, which is far away from the detection substrate, is a touch surface,

a touch member in contact with the touch surface forms a first image on a detection surface of a photosensitive element through the optical element;

an interference light source incident at a certain distance from the touch surface forms a second image on the detection surface of the photosensitive element through the optical element;

the definition of the first image is greater than the definition of the second image.

2. The optical touch screen of claim 1, wherein the optical element comprises a plurality of lenses and a transparent film in a matrix arrangement in a same plane, the lenses being disposed in the transparent film.

3. The optical touch screen of claim 2 wherein the distance between the touch surface of the optical element and the lens is D, the distance between the lens and the detection surface of the light sensitive element is D, the focal length of the lens is f, and the relationship that D is greater than f and less than 2f, and D is greater than 2f is satisfied.

4. The optical touch screen of claim 3, wherein the distance between the touch surface of the optical element and the lens is D, the distance between the lens and the detection surface of the photosensitive element is D, and the focal length of the lens is f, and satisfies the relationship of 1/f-1/D + 1/D.

5. The optical touch screen of claim 4 wherein D is 1.5f and D is 3 f.

6. An optical touch screen according to claim 2, wherein the lens is a fresnel lens.

7. The optical touch screen of claim 6, wherein the focal length f of the lens is in the range of 0.1mm to 3 mm.

8. The optical touch screen of claim 1, further comprising a calculating unit for calculating a distance from the touch member to the touch surface based on an imaging formula of object height/image height/object distance/image distance, based on a size of a first image formed by the detection surface of the touch member on the photosensitive element.

9. The optical touch screen of any of claims 2-8, wherein the photosensors are arranged in an mxn matrix, the lenses are arranged in an mxn matrix, and wherein M is less than or equal to M, and N is less than or equal to N, and wherein M, N, M, and N are natural numbers.

10. A display device comprising an optical touch screen according to any one of claims 1 to 9.