Optical multi-touch detection control method

Abstract

The present invention discloses an optical multi-touch detection control method, including defining a cascade chip for controlling a touch screen; the cascade chip includes a plurality of chips serially cascaded in sequence, and each chip integrates a plurality of staggered LEDs and PD sampling points; the number of the LEDs and PD sampling points matches the size of the touch screen; the light-emitting angle of the LED and the receiving angle of the PD sampling point are selected, so that the PD sampling point corresponding to the selected LED can receive the exposure when it is exposed, and after all LEDs are exposed successively, sampling and ADC conversion are performed via the PD sampling point that can receive the exposure, and the result data of the ADC conversion is sent to the CPU in a cascade manner; the CPU compares the result data of the ADC conversion with the background data of the PD sampling point collected in advance, and determines the touch condition of the touch screen according to the change amount obtained by the comparison. The PCB wiring of the scheme is simple, and the result sent is a digital signal, which is easy for the CPU to process and not easily interfered with. Thereby reducing the power consumption of the system and making the touch effect more ideal.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to an optical multi-touch detection control method. Background Art

[0002] In the electronic products used in today's world, touch screen is a new input device. Compared with the traditional key input method, touch screen input is more user-friendly; it meets the needs of users to a greater extent with the most intuitive and convenient human-computer interaction; so the natural input method of touch screen quickly won the market's recognition. At present, the types of touch screens mainly include capacitive, resistive, optical, etc. Capacitive and resistive touch screens are widely used on small and medium-sized screens, but it is difficult to achieve on large and extra-large screens. The main problem is that the cost is too high, and the current technology has not met the market demand. The optical touch screen just makes up for the above shortcomings, so the optical touch screen is widely used on large and extra-large screens.

[0003] like Figure 2 As shown in the figure, the optical touch control commonly used in the market is controlled by discrete components. The left figure is LED exposure control, CTR0 controls P0, and periodic exposure; the right figure is PD sampling control, CTR1 controls P1, whether the exposure voltage is output, R0 is the B pole clamp of BJT, when the PD is irradiated with strong light, current is generated, and BJT initially amplifies the current output. This circuit is used to perform the following two conventional optical touch control methods:

[0004] 1. Single-point optical touch control;

[0005] like Figure 3 As shown, LED x1 ~LED xn With LED y1 ~LED ym Composed of X-axis and Y-axis light-emitting arrays, PD x1 ~PD xn With LED y1 ~LED ym The X-axis and Y-axis photosensitive arrays are formed. Since the LED used is a laser, its light emission corresponds to light sensitivity one by one. The number of n and m values ​​is adjusted according to the size of the screen. The LED exposure is turned on in time-sharing order, and the PD light sensitivity is also turned on in time-sharing order. All light sensitive outputs are connected to node C. R1 is the resistance from point C to ground. The voltage at point C is amplified by the amplifier AMP and converted to the high-speed ADC. The conversion result is sent to the high-speed CPU for processing. According to the timing and the conversion value corresponding to the PD, it can be calculated that the light at that position on the screen is blocked, so that the point is touched.

[0006] This touch control method is only applicable to single-point touch. If it is multi-point touch, it will be easy to make mistakes, such as Figure 3 If points A and B are touched at the same time, two other points A' and B' will appear through cross-judgment of the light matrix (commonly known as ghost points). Due to the appearance of points A' and B', it is easy for the CPU to make mistakes when making judgments. Similarly, if more points are touched, the ghost points generated will increase exponentially, and the probability of error will be even greater.

[0007] 2. Multi-point optical touch control:

[0008] like Figure 4 As shown, the same LED x1 ~LED xn With LED y1 ~LED ym Composed of X-axis and Y-axis light-emitting arrays, PD x1 ~PD xn With LED y1 ~LED ym The X-axis and Y-axis photosensitive arrays are formed. Since the LEDs used have a certain light-emitting angle, the light from each LED can shine on each PD photosensitive module, so the entire light matrix is ​​(n+m)*(n+m). Similarly, the n and m values ​​are adjusted according to the actual size of the touch screen, and one of the LEDs is exposed according to the light-emitting timing. At this time, all PDs will be sensitive to light. If all PD output nodes are connected together, and the ADC module can only sample the output of one PD at a time, the LED needs to be exposed repeatedly (n+m) times, and all PD outputs are converted one by one. After all sampling is completed, the next LED is exposed, and then all PD outputs are sampled one by one for conversion.

[0009] Since the light matrix is ​​(n+m)*(n+m), the ghost point problem of multi-touch can be completely solved. However, the ADC conversion needs to be performed (n+m)*(n+m) times for each frame. Since the number of conversions increases exponentially, the ADC sampling and conversion requires extremely high speed. Assuming (n+m)=256, it takes 65536 times to complete the conversion of one frame. In order to achieve the effect of multi-touch without losing points, we need to convert at least 50HZ, that is, the time for each frame is 20mS, so the average time for each single sampling and conversion is only 300nS. In such a short time, the ADC cannot complete the sampling and conversion. At this time, multiple ADCs are needed for sampling and conversion (such as Figure 4Assume again that we use 6-channel ADC for conversion, so that the time of single sampling and conversion is close to 2uS, which can basically meet the ADC conversion, but at this time the LED exposure time is less than 2uS. Considering the photoelectric conversion energy of PD, the light-emitting current of LED needs to be increased to more than 1A, and the area of ​​PD's photosensitive unit needs to be increased to achieve the effect of multi-point touch.

[0010] In summary, these two solutions have the following problems:

[0011] 1. The light-emitting and photosensitive units are controlled by discrete components, which makes the device cost higher and the processing more complicated; at the same time, more control signals are required, making PCB layout more difficult.

[0012] 2. The single-point touch control method cannot achieve multi-point touch, which makes the application defective; the multi-point touch control solution requires multiple ADCs for sampling and conversion, and the LED exposure current is huge, which increases the system's power consumption and hardware cost.

[0013] 3. All PD outputs are connected together on the PCB, the signal line span is very large, and this line is an analog signal line, which is very susceptible to interference.

[0014] 4. The ADC sampling conversion of LED exposure time is very short, which is easily interfered by the random noise of the system, and is prone to insensitivity or false triggering during multi-point calculation. Summary of the invention

[0015] In view of the defects in the prior art, an embodiment of the present invention provides an optical multi-touch detection control method, thereby solving many problems such as high device cost, complex PCB layout, high system power consumption, and susceptibility to interference.

[0016] To achieve the above object, an embodiment of the present invention provides an optical multi-touch detection control method, the method comprising:

[0017] A cascade chip for controlling a touch screen is defined; the cascade chip comprises a plurality of chips cascaded in series in sequence, each chip internally integrates a plurality of staggered LEDs and PD sampling points; the number of the LEDs and PD sampling points matches the size of the touch screen;

[0018] The light emitting angle of the selected LED and the receiving angle of the PD sampling point are selected so that the PD sampling point corresponding to the selected LED can receive the exposure when the selected LED is exposed. After all LEDs are exposed one by one, the PD sampling points that can receive the exposure are sampled and ADC converted, and the result data of the ADC conversion is sent to the CPU in a cascade manner.

[0019] The CPU compares the result data converted by the ADC with the background data of the PD sampling points collected in advance, and determines the touch status of the touch screen according to the change amount obtained by the comparison.

[0020] Preferably, the collection of background data of PD sampling points includes: after the CPU initiates a frame synchronization instruction, all LEDs are turned off, and then all PD sampling points are sampled and ADC converted, and the converted non-exposure data is sent to the CPU for storage as the background data of the PD sampling points.

[0021] Furthermore, before the CPU initiates the frame synchronization instruction, the process further includes:

[0022] The chip address is configured according to the address configuration instruction initiated by the CPU, so that each chip obtains the corresponding chip address;

[0023] The internal registers of the chip are configured according to the read and write instructions initiated by the CPU, and the read and write parameters of the internal registers of the chip are controlled to meet the screen detection requirements.

[0024] Furthermore, the chip address is configured according to the address configuration instruction initiated by the CPU so that each chip obtains the corresponding chip address, including:

[0025] A corresponding address is configured for each chip, wherein the chip is provided with a data input terminal DI and a data output terminal DO;

[0026] Under no-function instructions, the chip outputs the data received by DI via DO. When receiving instructions initiated by the CPU, DO outputs the data corresponding to the instructions. After the corresponding data output is completed, it continues to output the data received by DI.

[0027] When the first chip receives the address configuration instruction and the starting address initiated by the CPU, it adds 1 to the received starting address and outputs it from the data output terminal DO1 of the first chip. When the CPU sends two identical addresses, the first chip confirms that it has received two identical addresses, adds 1 to the received address as the chip address of the first chip, and transmits it to the second chip.

[0028] The data input terminal DI2 of the second chip receives the address configuration instructions, the starting address, address 1, and address 1 in sequence;

[0029] The address configuration instruction, starting address, address 1, address 2, and then address 2 are sent out in sequence through DO2 of the second chip; when address 2 is received twice in succession, the second chip is locked to address 2, and so on, until the data input terminal DIn of the last chip n receives the address configuration instruction, address 0, address 1, address 2, address 3... address (n-1), address (n-1) in sequence;

[0030] The address (n-1) received twice in succession, chip n is locked as address n, and the address configuration instruction is output in sequence through the data output terminal DOn of chip n, followed by address 0, address 1, address 2, address 3... address (n-1), address n, address n; when the CPU receives address n twice, the address configuration of n chips is completed; where n is the total number of chips.

[0031] Further, the configuration chip internal register includes: defining a write instruction as (instruction part + IC address + write control bit + chip internal address + configuration content); defining a read instruction as (instruction part + IC address + read control bit + chip internal address);

[0032] The contents of the internal register include: exposure start address, exposure time, exposure current, sampling start address, sampling end address, sampling time, and ADC conversion time.

[0033] Preferably, the step of exposing all LEDs one by one comprises:

[0034] Send LED exposure and serial shift instructions, and expose all LEDs one by one according to the pre-configured exposure first address:

[0035] Exposure starts with LED1 of the first address IC. When the exposure time of LED1 reaches the pre-configured time, the exposure of LED1 is turned off.

[0036] Send the LED exposure and serial shift command again, LED2 starts to expose, and when the exposure time reaches the pre-configured time, LED2 exposure is turned off, and so on, until the last LED exposure time reaches the pre-configured time.

[0037] Preferably, the sampling and ADC conversion via the PD sampling point capable of receiving exposure includes:

[0038] After each LED exposure is completed, the corresponding PD is sampled and ADC converted by the designated chip, and the ADC conversion data corresponding to each PD sampling point after LED exposure is read after the ADC conversion is completed.

[0039] Preferably, sending the result data converted by the ADC to the CPU in a cascade manner includes:

[0040] When the data input terminal DI1 of the first chip receives the instruction to read the ADC result data, all the PD sampling and conversion data are sent out in sequence through the data output terminal DO1 of the first chip. After the data of the first chip is sent out, the second chip immediately sends out the data of the second chip. The subsequent chips are cascaded in sequence. After chip n receives the data of chip (n-1), it sends the data to the CPU. The CPU obtains the ADC conversion result of each PD sampling point according to the order of the received data.

[0041] Preferably, the CPU compares the result data converted by the ADC with the background data of the PD sampling points collected in advance, and determines the touch status of the touch screen according to the change amount obtained by the comparison, including:

[0042] Based on the consistency between the background data of the PD sampling point and the ADC conversion result data corresponding to each PD sampling point after LED exposure, it is judged whether the surrounding environment has changed. If the two are inconsistent, it means that the surrounding environment of the touch screen has changed;

[0043] When it is determined that the environment around the touch screen has changed, the internal register configuration parameters of the chip are adjusted according to the difference between the background data of the PD sampling point and the result data of the ADC conversion; and by comparing the difference with the preset range threshold, it is determined whether the touch screen is touched; if the difference is less than the preset range threshold, it means that the light corresponding to the PD sampling point is blocked, and the touched position of the touch screen is determined according to the blocked light map.

[0044] Furthermore, assuming that the selected touch screen has 256 LEDs and PD points, the difference between the background data of the PD sampling point and the result data converted by the ADC is determined by the following formula:

[0045]

[0046] In the formula, V01~V0 256 Indicates the ADC data obtained when not exposed; V11~V1 256 Indicates the ADC data obtained when the first LED is exposed; VD11~VD1 256 It indicates that the image data obtained by exposure of LED1 is subtracted from the image data without exposure.

[0047] Compared with the closest prior art, the beneficial effects of the present invention are:

[0048] The optical multi-touch detection control method provided by the present invention is an integrated circuit solution, which integrates multiple LED controls and multiple PD sampling into one chip, and cascades multiple chips in a serial cascade manner, which greatly reduces the components of the system. The chips can be cascaded in multiple ways according to the size of the screen, and can adapt to screens of different sizes;

[0049] Only a few signal lines are needed to control the exposure, PD sampling and ADC conversion of each LED. The LED exposure control and PD sampling ADC conversion are processed inside the chip, which greatly reduces peripheral devices. At the same time, the converted ADC result data is sent to the CPU for processing, which makes PCB wiring simple, and convenient for processing and assembly. The signal lines are all digital lines, and the results sent are digital signals, which are easy for the CPU to process and not easily interfered with, thereby reducing system power consumption and making the touch effect more ideal.

[0050] Each chip has an integrated ADC that can perform data conversion in parallel, reducing exposure current and system power consumption; and the chip has integrated function registers that can be configured to adapt to touch detection in different environments.

[0051] The invention effectively solves many problems caused by conventional single-point optical touch control or multi-point optical touch control, such as high device cost, complex PCB layout, high system power consumption, and susceptibility to interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0053] Figure 1 This is a flow chart of an optical multi-touch detection control method provided by the present invention;

[0054] Figure 2 It is a discrete component control schematic diagram provided by the background technology;

[0055] Figure 3 It is a schematic diagram of single-point optical touch control provided by the background technology;

[0056] Figure 4 It is a schematic diagram of multi-point optical touch control provided by the background technology;

[0057] Figure 5 It is a schematic diagram of the internal functional modules of the chip provided by the present invention;

[0058] Figure 6 It is a schematic diagram of the chip peripheral circuit structure provided by the present invention;

[0059] Figure 7 It is a schematic diagram of the optical path of the optical touch screen provided by the present invention;

[0060] Figure 8It is a chip address acquisition timing diagram provided by the present invention;

[0061] Fig. 9 It is a schematic diagram of LED successive exposure control provided by the present invention;

[0062] Fig.10 This is a schematic diagram of PD conversion data transmission control provided by the present invention;

[0063] Fig.11 The present invention provides a CPU system control chip and a touch detection flow chart.

[0064] Fig.12 It is a schematic diagram of PD conversion data provided by the present invention;

[0065] Fig.13 It is a schematic diagram of multi-touch optical occlusion provided by the present invention. DETAILED DESCRIPTION

[0066] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0067] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0068] Example 1: Please refer to Figure 1 , is an optical multi-touch detection control method provided by Embodiment 1 of the present invention, such as Figure 1 As shown, the method may include the following steps:

[0069] S101 defines the cascade chip that controls the touch screen; Figure 7 As shown, the cascade chip includes a plurality of chips that are serially cascaded in sequence, such as Figure 6 As shown, each chip integrates multiple staggered LEDs and PD sampling points; the number of LEDs and PD sampling points matches the size of the touch screen;

[0070] In addition, the chip also integrates signal amplifiers, ADC and function registers; Figure 5 As shown in the figure, the functional module block diagram and PAD pin function of the chip are described. Among them, CKI is the clock input, DI[j:1] is the data input, and the DI bit width can be configured according to the speed requirements, so that the host (CPU) can configure the functional registers and control instructions inside the chip through CKI and DI; the internal timing control of the chip controls the LED exposure timing to convert the PD sampling timing; at the same time, the result data of the ADC conversion and the content of the internal functional register can also be read;

[0071] S102 selects the light emitting angle of the LED and the receiving angle of the PD sampling point, so that the PD sampling point corresponding to the selected LED can receive the exposure when the selected LED is exposed. After all LEDs are exposed one by one, sampling and ADC conversion are performed through the PD sampling point that can receive the exposure, and the result data of the ADC conversion is sent to the CPU in a cascade manner;

[0072] S103 The CPU compares the result data converted by the ADC with the background data of the PD sampling points collected in advance, and determines the touch status of the touch screen according to the change amount obtained by the comparison.

[0073] The background data of the PD sampling points collected in advance in step S103 can be processed after step S101 is completed, specifically including: after the CPU initiates a frame synchronization instruction, all LEDs are turned off, and then all PD sampling points are sampled and ADC converted, and the converted non-exposure data is sent to the CPU for storage as the background data of the PD sampling points.

[0074] Before the CPU initiates the frame synchronization instruction, the following steps are also included:

[0075] 1. Configure the chip address according to the address configuration instruction initiated by the CPU, so that each chip obtains the corresponding chip address;

[0076] 2. Configure the internal registers of the chip according to the read and write instructions initiated by the CPU, and control the read and write parameters of the internal registers of the chip to meet the screen detection requirements.

[0077] Among them, the chip address is configured according to the address configuration instruction initiated by the CPU so that each chip obtains the corresponding chip address, including:

[0078] A corresponding address is configured for each chip, wherein the chip is provided with a data input terminal DI and a data output terminal DO;

[0079] Under no-function instructions, the chip outputs the data received by DI via DO. When receiving instructions initiated by the CPU, DO outputs the data corresponding to the instructions. After the corresponding data output is completed, it continues to output the data received by DI.

[0080] When the first chip receives the address configuration instruction and the starting address initiated by the CPU, it adds 1 to the received starting address and outputs it from the data output terminal DO1 of the first chip. When the CPU sends two identical addresses, the first chip confirms that it has received two identical addresses, adds 1 to the received address as the chip address of the first chip, and transmits it to the second chip.

[0081] The data input terminal DI2 of the second chip receives the address configuration instructions, the starting address, address 1, and address 1 in sequence;

[0082] The address configuration instruction, starting address, address 1, address 2, and then address 2 are sent out in sequence through DO2 of the second chip; when address 2 is received twice in succession, the second chip is locked to address 2, and so on, until the data input terminal DIn of the last chip n receives the address configuration instruction, address 0, address 1, address 2, address 3... address (n-1), address (n-1) in sequence;

[0083] The address (n-1) received twice in succession, chip n is locked as address n, and the address configuration instruction is output in sequence through the data output terminal DOn of chip n, followed by address 0, address 1, address 2, address 3... address (n-1), address n, address n; when the CPU receives address n twice, the address configuration of n chips is completed; where n is the total number of chips.

[0084] Among them, configuring the internal register of the chip includes: defining the write instruction as (instruction part + IC address + write control bit + chip internal address + configuration content); defining the read instruction as (instruction part + IC address + read control bit + chip internal address);

[0085] The contents of the internal register include: exposure start address, exposure time, exposure current, sampling start address, sampling end address, sampling time, and ADC conversion time.

[0086] In step S102, exposing all LEDs one by one includes:

[0087] Send LED exposure and serial shift instructions, and expose all LEDs one by one according to the pre-configured exposure first address:

[0088] Exposure starts with LED1 of the first address IC. When the exposure time of LED1 reaches the pre-configured time, the exposure of LED1 is turned off.

[0089] Send the LED exposure and serial shift command again, LED2 starts to expose, and when the exposure time reaches the pre-configured time, LED2 exposure is turned off, and so on, until the last LED exposure time reaches the pre-configured time.

[0090] In step S102, sampling and ADC conversion are performed via the PD sampling point that can receive exposure, including:

[0091] After each LED exposure is completed, the corresponding PD is sampled and ADC converted by the designated chip, and the ADC conversion data corresponding to each PD sampling point after LED exposure is read after the ADC conversion is completed.

[0092] In step S102, sending the result data converted by the ADC to the CPU in a cascade manner includes:

[0093] When the data input terminal DI1 of the first chip receives the instruction to read the ADC result data, all the PD sampling and conversion data are sent out in sequence through the data output terminal DO1 of the first chip. After the data of the first chip is sent out, the second chip immediately sends out the data of the second chip. The subsequent chips are cascaded in sequence. After chip n receives the data of chip (n-1), it sends the data to the CPU. The CPU obtains the ADC conversion result of each PD sampling point according to the order of the received data.

[0094] In step S103, the CPU compares the result data converted by the ADC with the background data of the PD sampling points collected in advance, and determines the touch status of the touch screen according to the change amount obtained by the comparison, including:

[0095] Based on the consistency between the background data of the PD sampling point and the ADC conversion result data corresponding to each PD sampling point after LED exposure, it is judged whether the surrounding environment has changed. If the two are inconsistent, it means that the surrounding environment of the touch screen has changed;

[0096] When it is determined that the environment around the touch screen has changed, the internal register configuration parameters of the chip are adjusted according to the difference between the background data of the PD sampling point and the result data of the ADC conversion; and by comparing the difference with the preset range threshold, it is determined whether the touch screen is touched; if the difference is less than the preset range threshold, it means that the light corresponding to the PD sampling point is blocked, and the touched position of the touch screen is determined according to the blocked light map.

[0097] Assuming that the selected touch screen has 256 LEDs and PD points, the difference between the background data of the PD sampling point and the result data converted by the ADC is determined by the following formula:

[0098]

[0099] In the formula, V01~V0 256 Indicates the ADC data obtained when not exposed; V11~V1 256 Indicates the ADC data obtained when the first LED is exposed; VD11~VD1 256 It indicates that the image data obtained by exposure of LED1 is subtracted from the image data without exposure.

[0100] Embodiment 2: The optical multi-touch detection control method provided in Embodiment 2 of the present invention has a specific operation process as follows:

[0101] 1. The chip can receive instructions: chip address configuration, chip internal control register reading and writing, LED exposure and serial shift and PD sampling conversion, reading ADC result data, frame synchronization.

[0102] Chip address configuration: Since the entire screen is controlled by multiple chips in cascade, each chip needs to be configured with a corresponding address. The chip normally directly outputs the data received by DI (equivalent to BUF) through DO. When under the function instruction, DO outputs the corresponding data, and returns to outputting the data of DI after the data to be output is completed. Figure 8 As shown, the CPU initiates the address configuration instruction and the starting address (the starting address is 0 in general). When the first chip receives the address configuration instruction and the starting address, the chip adds 1 to the received address and outputs it from DO1. The CPU sends out two identical addresses. After chip 1 confirms that it has received two identical addresses, it adds 1 to the received address as the chip address of the chip. Similarly, the first chip will also send two addresses plus 1 to the next chip. Let's look at chip 2. Since the DI1 of chip 1 is directly sent to DO1 when the CPU sends the address configuration instruction and the starting address, I see from chip 2 that DI2 first receives the address configuration instruction, then receives the starting address 0, then receives address 1, and then receives address 1 again. DO2 also sends out the address configuration instruction first, then sends out address 0, then sends out address 1, then sends out address 2, and then sends out address 2 again. Like chip 1, when address 1 is received twice in succession, the chip is locked to address 2. By analogy, to the last chip n, DIn first receives the address configuration instruction, then address 0, address 1, address 2, address 3... Address (n-1), address (n-1), address (n-1) is received twice in succession, so chip n locks address n, and DOn outputs address configuration instructions, then address 0, address 1, address 2, address 3... Address (n-1), address n, address n, DOn is sent back to the CPU. When the CPU receives address n twice, it knows that there are n chips cascaded on the entire screen. At this time, the address configuration of the entire chip is completed, and each chip has obtained its corresponding address.

[0103] Read and write the chip internal control register: its write instruction consists of (instruction part + IC address + write control bit + chip internal address + configuration content); its read instruction consists of (instruction part + IC address + read control bit + chip internal address); according to the needs of the application, the main contents of the internal register are as follows: exposure first address, exposure time, exposure current, sampling first address, sampling end address, sampling time, ADC conversion time, etc. When the IC address sent by the CPU is 0, it will be a global configuration, and all ICs will be read or written.

[0104] Frame synchronization: When the chip starts to detect or all LEDs are exposed, a frame synchronization command is issued, so that each chip can return to the previous configuration, so there is no need to reconfigure it. After the frame synchronization command, all LEDs are turned off, and then all PDs will perform sampling ADC conversion, and then send the converted data to the CPU for storage. The data obtained this time is non-exposure data (that is, PD background data).

[0105] LED exposure and serial shift and PD sampling conversion: After configuring the exposure first address, send LED exposure and serial shift instructions, such as Fig. 9 As shown, LED1 of the first address IC starts to expose, and when the exposure time reaches the configured time, LED1 exposure is turned off, and LED exposure and serial shift instructions are sent again, and LED2 starts to expose similarly, and when the exposure time reaches the configured time, LED2 exposure is turned off, and so on, each LED is exposed one by one and turned off when the exposure time is reached, so that all LEDs can be exposed one by one.

[0106] Read ADC result data: After each LED exposure, the specified chip will sample and convert the corresponding PD, such as Fig.10 As shown, after the ADC conversion is completed, the CPU will initiate an instruction to read the ADC result data. When DI1 of chip 1 receives the instruction to read the ADC result data, DO1 will then send out all the PD sampled and converted data in sequence. After chip 1 has sent the data, chip 2 will immediately send out the data of chip 2. The subsequent chips are cascaded in sequence. After chip n has received the data of chip (n-1), it will also send out the data. Finally, the data is sent to the CPU. The CPU knows the ADC conversion result of each PD based on the order of the received data.

[0107] 2. System control timing: such as Fig.11 As shown, the CPU first initiates the address configuration instruction so that each chip obtains its corresponding chip address; then configures the internal registers of the chip so that its corresponding parameters meet the screen detection requirements; then sends the frame synchronization instruction to read the background data of all PDs; then sends the LED exposure and serial shift instructions, and then reads the result of the PD after each LED is exposed, and exposes and reads the result data in turn until all LEDs are exposed and the CPU reads all the data. The CPU analyzes the data in real time to see if the environment has changed, and if so, adjusts the internal register configuration of the chip. This cycle is repeated to detect whether the screen is touched.

[0108] 3. Touch detection: When the CPU initiates frame synchronization and reads the conversion data of all PDs, the background data of all PDs is obtained, such as Fig.12As shown, each PD gets the corresponding ADC conversion data; similarly, each LED exposure will also get the corresponding ADC conversion data for each PD; assuming that the optical touch screen we selected has 256 LEDs and PD points (i.e. 2y*k=256), the ADC data obtained when not exposed is V01~V0 256 ; The ADC data obtained when the first LED is exposed is V11~V1 256 ; And so on, the ADC data obtained when the 256th LED is exposed is V2561~V256 256 ;

[0109]

[0110] As shown in formula ①, we subtract the image data obtained by LED1 exposure from the image data without exposure to obtain VD11~VD1 256 Data. According to the LED light emitting angle and the distribution of PD on the screen (such as Figure 7 As shown in the figure, the PD that each LED light can illuminate is the effective data, and other data do not need to participate in the calculation. When the light is blocked, the value corresponding to its VD1 will be very small or 0. At this time, we set a threshold VD th , when the VD1 of the point to be calculated n <VD th When the light is blocked, the light is blocked. Similarly, each LED will get the ADC conversion data of the corresponding PD after exposure; the corresponding point is subtracted from the background to determine whether the light is blocked. Since the light on the entire screen is dense, one touch point will cause multiple light rays to be blocked, such as Fig.13 As shown in the figure, when points A and B are touched, the corresponding multiple light rays are blocked. According to the light diagram on the screen, the CPU can accurately locate the corresponding position through internal calculation.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. An optical multi-touch detection control method, characterized in that: The method comprises: A cascade chip for controlling a touch screen is defined; the cascade chip comprises a plurality of chips cascaded in series in sequence, each chip internally integrates a plurality of staggered LEDs and PD sampling points; the number of the LEDs and PD sampling points matches the size of the touch screen; The light-emitting angle of the selected LED and the receiving angle of the PD sampling point are selected so that the PD sampling point corresponding to the selected LED can receive exposure when the selected LED is exposed. After all LEDs are exposed one by one, sampling and ADC conversion are performed through the PD sampling point that can receive exposure, and the result data of the ADC conversion is sent to the CPU in a cascade manner, wherein when the data input terminal DI1 of the first chip receives the instruction to read the ADC result data, all the PD sampling and conversion data are sent out in sequence through the data output terminal DO1 of the first chip, and the second chip sends out the data of the second chip immediately after the data of the first chip is sent out. The subsequent chips are cascaded in sequence, and chip n sends the data to the CPU after receiving the data of chip (n-1). The CPU obtains the ADC conversion result of each PD sampling point according to the order of the received data; The CPU compares the result data of ADC conversion with the background data of the PD sampling points collected in advance, and determines the touch status of the touch screen according to the change amount obtained by the comparison. The CPU determines whether the surrounding environment has changed based on the consistency between the background data of the PD sampling points and the ADC conversion result data corresponding to each PD sampling point after LED exposure. If the two are inconsistent, it means that the surrounding environment of the touch screen has changed. When it is determined that the environment around the touch screen has changed, the internal register configuration parameters of the chip are adjusted according to the difference between the background data of the PD sampling point and the result data of the ADC conversion; and by comparing the difference with the preset range threshold, it is determined whether the touch screen is touched; if the difference is less than the preset range threshold, it means that the light corresponding to the PD sampling point is blocked, and the touched position of the touch screen is determined according to the blocked light map.

2. The method according to claim 1, characterized in that The collecting of background data of PD sampling points includes: after the CPU initiates a frame synchronization instruction, all LEDs are turned off, and then all PD sampling points are sampled and ADC converted, and the converted non-exposure data is sent to the CPU for storage as the background data of the PD sampling points.

3. The method according to claim 2, characterized in that Before the CPU initiates the frame synchronization instruction, the following steps are also included: The chip address is configured according to the address configuration instruction initiated by the CPU, so that each chip obtains the corresponding chip address; The internal registers of the chip are configured according to the read and write instructions initiated by the CPU, and the read and write parameters of the internal registers of the chip are controlled to meet the screen detection requirements.

4. The method according to claim 3, characterized in that The chip address configuration is performed according to the address configuration instruction initiated by the CPU so that each chip obtains the corresponding chip address, including: A corresponding address is configured for each chip, wherein the chip is provided with a data input terminal DI and a data output terminal DO; Under no-function instructions, the chip outputs the data received by DI via DO. When receiving instructions initiated by the CPU, DO outputs the data corresponding to the instructions. After the corresponding data output is completed, it continues to output the data received by DI. When the first chip receives the address configuration instruction and the starting address initiated by the CPU, it adds 1 to the received starting address and outputs it from the data output terminal DO 1 of the first chip. When the CPU sends two identical addresses, the first chip confirms that it has received two identical addresses, adds 1 to the received address as the chip address of the first chip, and transmits it to the second chip. The data input terminal DI2 of the second chip receives the address configuration instructions, the starting address, address 1, and address 1 in sequence; The address configuration instruction, starting address, address 1, address 2, and then address 2 are sent out in sequence through DO2 of the second chip; when address 2 is received twice in succession, the second chip is locked to address 2, and so on, until the data input terminal DIn of the last chip n receives the address configuration instruction, address 0, address 1, address 2, address 3... address (n-1), address (n-1) in sequence; The address (n-1) received twice in succession, chip n is locked as address n, and the address configuration instruction is output in sequence through the data output terminal DOn of chip n, followed by address 0, address 1, address 2, address 3... address (n-1), address n, address n; when the CPU receives address n twice, the address configuration of n chips is completed; where n is the total number of chips.

5. The method according to claim 3, characterized in that The configuration chip internal register includes: defining a write instruction as (instruction part + IC address + write control bit + chip internal address + configuration content); defining a read instruction as (instruction part + IC address + read control bit + chip internal address); The contents of the internal register include: exposure start address, exposure time, exposure current, sampling start address, sampling end address, sampling time, and ADC conversion time.

6. The method according to claim 1, characterized in that The sequential exposure of all LEDs comprises: Send LED exposure and serial shift instructions, and expose all LEDs one by one according to the pre-configured exposure first address: Exposure starts with LED1 of the first address IC. When the exposure time of LED1 reaches the pre-configured time, the exposure of LED1 is turned off. Send the LED exposure and serial shift command again, LED2 starts to expose, and when the exposure time reaches the pre-configured time, LED2 exposure is turned off, and so on, until the last LED exposure time reaches the pre-configured time.

7. The method according to claim 1, characterized in that The sampling and ADC conversion via the PD sampling point capable of receiving exposure includes: After each LED exposure is completed, the corresponding PD is sampled and ADC converted by the designated chip, and the ADC conversion data corresponding to each PD sampling point after LED exposure is read after the ADC conversion is completed.

8. The method according to claim 1, characterized in that Assuming that the selected touch screen has 256 LEDs and PD points, the difference between the background data of the PD sampling point and the result data converted by the ADC is determined by the following formula: Wherein, V0 1~V0 256 represent ADC data obtained when not exposed; V1 1~V1 256 represent ADC data obtained when the first LED is exposed; VD1 1~VD1 256 represent data obtained by subtracting image data obtained by LED1 exposure from image data without exposure.

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