AGC control circuit, infrared touch frame and infrared touch screen

Abstract

The utility model relates to an AGC (Automatic Gain Control) control circuit, an infrared touch frame and an infrared touch screen. The AGC control circuit comprises a controller and at least one DAC (Digital-to-Analog Converter) circuit connected to an I / O (Input / Output) pin of the controller, wherein the DAC circuit is connected with a signal conditioning circuit of the infrared lamp tube; the DAC circuit comprises a resistance network connected to a plurality of I / O pins of the controller, and the output end of the resistance network is connected to the signal conditioning circuit; each I / O pin corresponds to a control bit of a digital control signal, and the I / O pins output high level or low level; the controller outputs a digital control signal to each DAC circuit through high and low levels of the I / O pin so as to adjust the infrared signal intensity of the infrared lamp tube; according to the technical scheme, the equipment cost of the DAC module can be reduced, the response speed is increased, and the application requirement of the infrared touch frame is met.

Description

Technical Field

[0001] The present application relates to the field of infrared touch control technology, and in particular to an AGC control circuit, an infrared touch frame and an infrared touch screen. Background Art

[0002] In the infrared touch frame, multiple groups of infrared lamps are distributed and arranged on the edge of the display screen, and then the infrared transmitting tube is controlled to emit infrared light and the infrared receiving tube is controlled to receive infrared light and convert it into an electrical signal. A series of gain adjustments are made to the intensity of the received infrared signal, and then A / D sampling is performed on the infrared signal (for digital quantization of analog signals). Based on whether the signal after adjustment and stabilization changes, it is judged whether there is an object blocking the infrared light, and the touch operation is judged to output the corresponding touch position coordinates, thereby realizing the click, line drawing, touch and other functions of the infrared touch frame.

[0003] In the infrared signal conditioning system of infrared lamps, such as Figure 1 As shown, Figure 1 The schematic diagram of the structure of an infrared signal strength adjustment system is an example, including a signal adjustment circuit 11 and a controller 12, wherein the signal adjustment circuit 11 includes a transmitting circuit adjustment module and a receiving circuit adjustment module; the transmitting circuit adjustment module and the receiving circuit adjustment module are usually implemented by an AGC (Automatic gain control) circuit, wherein the transmitting circuit adjustment module includes a TAGC (Transmit Automatic gain control) circuit of an infrared transmitting tube, and the TAGC circuit adjusts the luminous intensity of the transmitting tube by controlling the luminous current of the infrared transmitting tube to change the infrared signal strength; the receiving circuit adjustment module includes a RAGC (Receive Automatic gain control) circuit of an infrared receiving tube, and the RAGC circuit adjusts the infrared signal strength by controlling the amplification factor of the infrared receiving signal. The controller 12 is mainly used for signal sampling and control functions, that is, by collecting the infrared signal strength, feedback adjusting TAGC and RAGC, so as to control the infrared signal strength.

[0004] At present, the MCU (Microcontroller Unit) chip used in the controller 12 is only equipped with a small number of DAC (Digital to Analog Converter) modules. Some settings do not have DAC modules and require additional DAC modules, which has high equipment costs. In addition, these additional DAC modules involve data communication and other processing with the MCU, resulting in a low response speed, which is difficult to meet the application requirements of the infrared touch frame. Utility Model Content

[0005] The purpose of the present application is to solve one of the above-mentioned technical defects and provide an AGC control circuit, an infrared touch frame and an infrared touch screen.

[0006] An AGC control circuit for controlling the infrared signal strength of an infrared lamp comprises: a controller, and at least one DAC circuit connected to an I / O pin of the controller; wherein the DAC circuit is connected to a signal conditioning circuit of the infrared lamp;

[0007] The DAC circuit includes a resistor network connected to a plurality of I / O pins of the controller, and an output end of the resistor network is connected to the signal conditioning circuit;

[0008] Each of the I / O pins corresponds to a control bit of a digital control signal, and the I / O pin outputs a high level or a low level;

[0009] The controller outputs a digital control signal to each of the DAC circuits through the high and low levels of the I / O pins to adjust the infrared signal intensity of the infrared lamp tubes.

[0010] An infrared touch frame comprises: a main board and a plurality of slave boards; wherein the main board comprises the AGC control circuit, and the slave boards are provided with an infrared transmitting tube array or an infrared receiving tube array;

[0011] The AGC control circuit adjusts the intensity of the infrared signal emitted by the infrared transmitting tube array, and amplifies and processes the intensity of the infrared signal received by the infrared receiving tube array.

[0012] An infrared touch screen comprises: a display screen and the infrared touch frame; wherein the infrared touch frame is arranged around the display screen.

[0013] This application has the following beneficial effects:

[0014] A resistor network is used to construct a DAC circuit on the I / O pin of the controller, and a digital control signal is output through the high and low levels of the I / O pin to adjust the infrared signal strength of the infrared lamp. This reduces the equipment cost of the DAC module and can improve the response speed to meet the application requirements of the infrared touch frame.

[0015] Additional aspects and advantages of the present application will be partially given in the following description, which will become apparent from the following description, or will be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0017] Figure 1 is a schematic diagram of an example infrared signal strength adjustment system structure;

[0018] Figure 2 is a schematic diagram of the structure of an AGC control circuit of an embodiment;

[0019] Figure 3 is a schematic diagram of an example DAC circuit structure;

[0020] Figure 4 This is an example of an I / O pin connection diagram;

[0021] Figure 5 This is a schematic diagram of an example infrared touch circuit board structure;

[0022] Figure 6 is another example of an infrared touch circuit board structure schematic diagram;

[0023] Figure 7 This is a schematic diagram of an infrared touch frame structure;

[0024] Figure 8 It is a schematic diagram of the structure of an infrared touch screen of an example. DETAILED DESCRIPTION

[0025] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be interpreted as limiting the present application.

[0026] Those skilled in the art will appreciate that, unless otherwise stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present application refers to the presence of the features, integers, steps, operations, but does not exclude the presence or addition of one or more other features, integers, steps, operations.

[0027] The present application aims at the situation that the DAC required by the AGC circuit used for the transmission and reception of the infrared lamp in the infrared touch frame is insufficient or the DAC speed is too slow to meet the use requirements, and designs an AGC control circuit. On the I / O pin of the controller (Microcontroller Unit, MCU), multiple DAC circuits are constructed by designing multiple resistor networks, each DAC circuit corresponds to a resistor network, and then the high and low levels of the I / O pin are used as signal outputs to convert the digital signals of multiple digits into analog signals, thereby realizing the digital-to-analog conversion function, which can be used to control the infrared signal strength of the infrared lamp. The AGC control circuit of the present application can reduce the use of DAC devices and save equipment costs when the number of DAC circuits is met. On the other hand, since the high and low level outputs of the I / O pin of the controller are used as the input of the DAC circuit, the output of the I / O pin has a good response speed, and the response speed of the DAC circuit can be improved accordingly. Furthermore, when the number of DAC circuits is insufficient or there is no DAC, a resistor network can be set to form a DAC circuit. When the I / O pins of the controller are met, the number of DAC circuits can be increased accordingly by increasing the number of resistor networks.

[0028] like Figure 2 As shown, Figure 2 The AGC control circuit 10 is a schematic diagram of the structure of an embodiment. The AGC control circuit 10 includes: a controller 12, the controller 12 has multiple I / O pins, and the controller 12 is connected to at least one DAC circuit 13 through the I / O pins; wherein the DAC circuit 13 is connected to the signal adjustment circuit 11 of the infrared lamp tube.

[0029] In this embodiment, the signal adjustment circuit 11 may include a current gain adjustment circuit 11a connected to the infrared transmitting tube and a signal gain adjustment circuit 11b connected to the infrared receiving tube, the current gain adjustment circuit 11a is used to control the luminous intensity of the infrared transmitting tube to change the infrared signal intensity, and the signal gain adjustment circuit 11b is used to control the amplification factor of the infrared receiving signal of the infrared receiving tube to adjust the infrared signal intensity; correspondingly, the DAC circuit 13 may include a first DAC circuit 131 connected to the current gain adjustment circuit 11a and a second DAC circuit 132 connected to the signal gain adjustment circuit 11b; exemplarily, as shown in the figure, the first DAC circuit 131 is connected to n I / O pins of the controller 12, and the second DAC circuit 132 is connected to m I / O pins of the controller 12, n and m are set values, wherein the value of n is positively correlated with the control accuracy of the current gain adjustment circuit, and the value of m is positively correlated with the control accuracy of the signal gain adjustment circuit.

[0030] In one embodiment, the first DAC circuit 131 and the second DAC circuit 132 have the same circuit structure, and the difference between the two is that the number of I / O pins of the controller 12 used is different, which is determined according to their respective control precisions. The more I / O pins used, the higher the control precision. The I / O pins of the controller 12 are used as the input of the DAC circuit, and the output of the I / O pins has a good output speed, which can also improve the response speed of the DAC circuit accordingly.

[0031] The DAC circuit 13 may include a resistor network connected to a plurality of I / O pins of the controller 12, and the output of the resistor network is connected to the signal conditioning circuit 11, such as the current gain conditioning circuit 11a and the signal gain conditioning circuit 11b in the above-mentioned embodiment.

[0032] Each of the I / O pins corresponds to a control bit of the digital control signal. The I / O pin outputs a high level or a low level. The controller 12 outputs a digital control signal to each DAC circuit 13 through the high and low levels of the I / O pins to adjust the infrared signal strength of the infrared lamp. Specifically, the high level corresponds to a "1" signal, and the value of "1" is the set high level V CC , the low level corresponds to “0” and takes the value 0, thereby a digital control signal of multiple control bits can be output through the controller 12.

[0033] For example, for the DAC circuit 13, refer to Figure 3 , Figure 3 1 is a schematic diagram of an exemplary DAC circuit structure, in which an R-2R resistor network is designed using 6 I / O pins of the controller 12 to build a DAC circuit. For example, the DAC circuit in the figure includes a plurality of first resistors corresponding to the plurality of I / O pins of the controller 12, and each I / O pin is connected to the first end of each first resistor; Figure 3 In the embodiment, the I / O0 to I / O5 pins of the controller 12 are connected to the first resistor R S1 , R S2 , R S3 , R S4 , R S5 , R S6 The first end, that is, the I / O0 pin is connected to the resistor R S1 、I / O1 pin connected to resistor R S2 、I / O2 pin connected to resistor R S3 、I / O3 pin connected to resistor R S4 、I / O4 pin connected to resistor R S5 、I / O5 pin connected to resistor R S6 .

[0034] A second resistor is connected between the second ends of two adjacent first resistors. Specifically, R S1 , R S2 Connect R B1 , R S2 , R S3 Connect R B2 , R S3 , R S4 Connect R B3 , R S4 , R S5 Connect R B4 , R S5 , R S6 Connect R B5 ;

[0035] In the first resistor, the second end of the first first resistor is also connected to the ground through the third resistor, and the second end of the last first resistor is used as the output end of the DAC circuit. Figure 3 In the resistor R S1 The second end is connected through the resistor R S7 Connect to ground, resistor R S6 The second end of the DAC serves as the output end DAC0 of the DAC circuit.

[0036] In one embodiment, the resistance of the first resistor is an integer multiple of the second resistor; illustratively, each resistor of the resistor network may also satisfy the following relationship:

[0037] R S1 =R S2 =R S3 =R S4 =R S5 =R S6 =R S7 =2R B1 =2R B2 =2R B3 =2R B4 =2R B5

[0038] In the DAC circuit 13 of this embodiment, only R S and R B The two resistors can be used to design a multi-bit DAC circuit structure, in which the I / O0-I / O5 pins of the controller 12 can output high and low levels, with the high level as V CC Taking the low level as 0 as an example, the DAC circuit 13 can obtain a conversion output of a 6-bit DAC digital control signal, and the calculation formula of the output analog signal is: DAC0 = (DORx ÷ 63) × V CC, where DORx is the real-time weight value; the weight value refers to the decimal number of binary. For example, the output level of the 6 I / O pins is represented by a digital signal of 000000 to 111111, then the corresponding decimal weight value is 0 to 63, that is, Figure 3 The maximum weight value in the DAC circuit shown is 63, and the corresponding DAC output voltage = (real-time weight value / 63) × V CC , where the real-time weight value is a decimal number converted from the binary value of the level output by the six I / O pins in real time, and the output value of the DAC circuit is positively correlated with the number of I / O pins connected to the DAC circuit that are set to a high level.

[0039] As in the technical solution of the above embodiment, since the I / O pin has the characteristic of high speed, it can be Figure 3 The technical solution shown can form a multi-bit high-precision high-speed DAC function with two resistors, which can be used for fast and accurate current regulation of infrared lamps.

[0040] In one embodiment, considering the situation that the driving capability may be insufficient due to the output capability of the DAC circuit, such as Figure 3 As shown, a buffer circuit 14 can also be provided between the output end of the resistor network and the signal conditioning circuit 11 to enhance the driving capability of the DAC circuit; specifically, the buffer circuit 14 can adopt an operational amplifier circuit, which can ultimately amplify the analog signal DAC0 to DACout for output.

[0041] As in the above-mentioned embodiment, the buffer circuit 14 can improve the signal regulation and driving capability of the DAC circuit 13 on the back end, and can adapt to the design requirements of different scenarios.

[0042] In one embodiment, in view of the infrared signal intensity adjustment requirements of the infrared transmitting tube and the infrared receiving tube, a differentiated design can be performed when designing the number of control bits of the DAC circuit 13; for example, Figure 2 In the figure, for the current gain adjustment circuit 11a for controlling the infrared emitting tube, each first DAC circuit 131 is connected to n I / O pins of the controller 12, and for the signal gain adjustment circuit 11b for controlling the infrared receiving tube, each second DAC circuit 132 is connected to m I / O pins of the controller 12; when designing the number of control bits of the DAC circuit 13, n and m are not equal.

[0043] As in the above embodiment, if the infrared emission has a higher control precision requirement, while the infrared reception has a relatively lower control precision requirement, then when designing the control bit, n can use more I / O pins, while m can be designed as a relatively small number of I / O pins. Through the above design, the I / O pins of the controller 12 can be more fully utilized, and the matching degree between the infrared emission and the infrared reception is higher. If the infrared emission has a relatively lower control precision requirement, while the infrared reception has a relatively higher control precision requirement, then m can be greater than n.

[0044] In one embodiment, when the I / O pins of the controller 12 are insufficient, some of the I / O pins may be multiplexed to implement a DAC circuit design with more channels.

[0045] According to this, if Figure 4 As shown, Figure 4 FIG. 1 is a schematic diagram of an exemplary I / O pin connection. A single-input multiple-output circuit 15, such as a shift register, a multiplexer, etc., can be connected to the I / O pin to selectively connect the I / O pin to one of the DAC circuits 13. The input end of the single-input multiple-output circuit 15 is connected to the I / O pin, and the output end is connected to multiple DAC circuits 13. For example, the input end of the single-input multiple-output circuit 15 can be connected to a time-division multiplexed I / O pin, so that part of the I / O pins are multiplexed when the DAC circuits 13 of different channels are used. Figure 4 In the figure, two 4-bit DAC circuits 13, including DAC circuit ① and DAC circuit ②, are connected to the I / O0-I / O3 pins of the controller 12, each I / O pin is respectively connected to a multiplexer K1~K4, and DAC circuit ① and DAC circuit ② multiplex the I / O0-I / O3 pins.

[0046] As in the above-mentioned embodiment, according to actual needs, some I / O pins can be reused while ensuring a certain response speed, so as to meet the usage requirements in different scenarios, thereby minimizing the equipment cost while meeting a certain response speed.

[0047] The following describes embodiments of an infrared touch frame and an infrared touch screen.

[0048] In this embodiment, the infrared touch circuit board 20 includes: a main board 21 and a plurality of slave boards 22 connected via a bus; wherein the main board is provided with the AGC control circuit 10 of any of the above-mentioned embodiments.

[0049] For example, Figure 5 As shown, Figure 5The infrared touch circuit board 20 is a schematic diagram of an example structure of an infrared touch circuit board. The infrared touch circuit board 20 includes a main board 21 provided with an AGC control circuit 10 and slave boards 22 (a total of 8 slave circuit boards are numbered ① to ⑧) distributed along the edge of the infrared touch frame, wherein the main board 21 is integrated on the slave board 22 numbered ①, and each slave board 22 is respectively provided with an infrared transmitting tube array or an infrared receiving tube array, or each slave board 22 is simultaneously provided with an infrared transmitting tube array or an infrared receiving tube array, and the main board 21 can control the infrared light signal intensity of the infrared transmitting tubes of the main board 21 and other slave boards 22 and amplify the infrared light signal of the infrared receiving tube through the AGC control circuit 10.

[0050] For example, Figure 6 middle, Figure 6 1 is another example of an infrared touch circuit board structure schematic diagram, the infrared touch circuit board 20 includes a main board 21 provided with an AGC control circuit 10 and slave boards 22 (numbered ① to ⑧, a total of 8 slave circuit boards) distributed along the edge of the infrared touch frame, each slave board 22 is respectively provided with an infrared transmitting tube array or an infrared receiving tube array, or, or each slave board 22 is simultaneously provided with an infrared transmitting tube array or an infrared receiving tube array, each slave board 22 is connected through a bus, and the main board 21 is an independently designed circuit board card, such as Figure 6 In the example, the slave boards 22 numbered ① to ⑧ are connected through a bus, the main board 21 is connected to the slave board 22 numbered ①, and the main board 21 can control the infrared light signal intensity of the infrared transmitting tube of each slave board 22 and amplify the infrared light signal of the infrared receiving tube through the AGC control circuit 10.

[0051] The infrared touch circuit board 20 of the above embodiment can reduce the equipment cost, improve the response speed and meet the application requirements of the infrared touch frame through the above AGC control circuit 10.

[0052] like Figure 7 As shown, Figure 7 It is a schematic diagram of an example infrared touch frame structure, where the infrared touch frame 30 includes the infrared touch circuit board 20 of the aforementioned embodiment, as well as an infrared transmitting tube array 31 and an infrared receiving tube array 32; wherein the infrared transmitting tube array 31 adjusts the intensity of the transmitted infrared signal under the control of the AGC control circuit 10, and amplifies and processes the intensity of the infrared signal received by the infrared receiving tube array 32.

[0053] Exemplarily, the total number of infrared transmitting tubes included in the infrared transmitting tube array 31 is N, and the total number of infrared receiving tubes in the infrared receiving tube array 32 is M. Generally, N = M. The infrared transmitting tube array 31 can be divided into j transmitting groups, and the k infrared transmitting tubes in each group are time-sharingly transmitted, that is, the infrared transmitting tubes of k channels are controlled to transmit in sequence, N = j × k; the infrared receiving tube array 32 can be divided into q scanning groups, and each group controls p infrared receiving tubes to receive at the same time, that is, it controls p channels at the same time, M = q × p.

[0054] As in the infrared touch frame 30 of the above embodiment, multiple channels can be controlled during transmission and reception control and adjustment. Meanwhile, the AGC control circuit 10 of the above embodiment can be used to reduce equipment cost, improve response speed, and meet application requirements of the infrared touch frame.

[0055] like Figure 8 As shown, Figure 8 The infrared touch screen 40 is a schematic diagram of an example structure of an infrared touch screen, wherein the infrared touch screen 40 comprises: a display screen 41 and an infrared touch frame 30; wherein the infrared touch frame 30 is arranged around the display screen 41. It can be used in various terminal devices, and the display screen can display the picture content, and the infrared touch frame has a touch positioning function.

[0056] The infrared touch screen of the above embodiment can be applied to various tablet terminals, such as educational tablet terminals, conference tablet terminals and other tablet terminals, etc.; by utilizing the AGC control circuit 10 of the above embodiment, the equipment cost can be reduced, the response speed can be improved, and the application requirements in more touch scenarios can be met.

[0057] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with those in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as here.

[0058] The above description is only a partial implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. An AGC control circuit for controlling the infrared signal strength of an infrared lamp, characterized in that: include: A controller, and at least one DAC circuit connected to an I / O pin of the controller; wherein the DAC circuit is connected to a signal conditioning circuit of an infrared lamp; The DAC circuit includes a resistor network connected to a plurality of I / O pins of the controller, and an output end of the resistor network is connected to the signal conditioning circuit; Each of the I / O pins corresponds to a control bit of a digital control signal, and the I / O pin outputs a high level or a low level; The controller outputs a digital control signal to each of the DAC circuits through the high and low levels of the I / O pins to adjust the infrared signal intensity of the infrared lamp tubes.

2. The AGC control circuit according to claim 1, characterized in that: A buffer circuit is also connected between the output end of the resistor network and the signal conditioning circuit to enhance the driving capability of the DAC circuit.

3. The AGC control circuit according to claim 2, characterized in that: The signal adjustment circuit includes a current gain adjustment circuit connected to the infrared emitting tube; The DAC circuit includes a first DAC circuit connected to the current gain adjustment circuit, and the first DAC circuit is connected to the current gain adjustment circuit.

4. The AGC control circuit according to claim 3, characterized in that: The signal adjustment circuit also includes a signal gain adjustment circuit connected to the infrared receiving tube; The DAC circuit further includes a second DAC circuit connected to the signal gain adjustment circuit, and the second DAC circuit is connected to the signal gain adjustment circuit.

5. The AGC control circuit according to claim 4, characterized in that: Each of the first DAC circuits is connected to n I / O pins of the controller, and each of the second DAC circuits is connected to m I / O pins of the controller.

6. The AGC control circuit according to claim 1, characterized in that: Also included is a single-input multiple-output circuit connected to the I / O pin of the controller, used to selectively connect the I / O pin to one of the DAC circuits; Wherein, the input end of the single-input multiple-output circuit is connected to the I / O pin, and the output end is connected to at least two DAC circuits.

7. The AGC control circuit according to claim 6, characterized in that: The input end of the single-input multiple-output circuit is connected to the I / O pin for time-division multiplexing.

8. The AGC control circuit according to claim 1, characterized in that: The resistor network includes: first resistors corresponding to a plurality of I / O pins one by one, each I / O pin is connected to a first end of the corresponding first resistor, and a second resistor is connected between the second ends of two adjacent first resistors; The second end of the first resistor among the first resistors is connected to the ground through the third resistor; the second end of the last resistor among the first resistors serves as the output end of the DAC circuit.

9. The AGC control circuit according to claim 8, characterized in that: The resistance values ​​of the first resistor and the third resistor are equal, and the resistance value of the first resistor is an integer multiple of the resistance value of the second resistor.

10. The AGC control circuit according to claim 8, characterized in that: The output value of the DAC circuit is positively correlated with the number of I / O pins connected to the DAC circuit that are set to a high level.

11. An infrared touch frame, characterized in that: include: A main board and a plurality of slave boards; wherein the main board comprises the AGC control circuit according to any one of claims 1 to 10, and the slave boards are provided with an infrared transmitting tube array or an infrared receiving tube array; The AGC control circuit adjusts the intensity of the infrared signal emitted by the infrared transmitting tube array, and amplifies and processes the intensity of the infrared signal received by the infrared receiving tube array.

12. An infrared touch screen, characterized in that: include: A display screen and the infrared touch frame as claimed in claim 11; wherein the infrared touch frame is arranged around the display screen.

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