A hardware circuit for physical buttons used in AR wearable products

Abstract

The utility model discloses a hardware circuit for physical buttons applied to AR wearable products, including a central processing unit and an ADC, wherein the central processing unit is connected to the ADC, and a plurality of resistors are connected in parallel to the pins of the ADC, and the plurality of resistors are grounded through buttons. The utility model can be applied to wearable products with high requirements on the thickness of wire harnesses, such as AR, VR, etc., and can effectively reduce the number of wire harnesses introduced by buttons; thus, in the application of AR products, the temples can be thinner, or the transmission lines can be smaller, the whole machine can be lighter, and the button experience can be better than that of the touchpad, etc.

Description

Technical Field

[0001] The utility model relates to the technical field of AR product button circuits, in particular to a hardware circuit of physical buttons applied to AR wearable products. Background Art

[0002] In recent years, augmented reality technology (AR), especially the hardware equipment technology of augmented reality, has made great progress. Due to the particularity of the form of wearable products such as AR glasses, the requirements for volume and weight are much more stringent than those of general mobile phones and tablets. Therefore, when designing hardware circuits, there are restrictions everywhere. When designing wearable products, the number of wiring harnesses used to implement buttons cannot be too many. If there are too many wiring harnesses, it will be very difficult to route the wires in the narrow space of the temples, which will cause the temples of AR glasses to become thicker and heavier, thus leaving a very poor experience for end users in terms of appearance and experience, greatly reducing the competitiveness of the product and losing the market.

[0003] Figure 1 This is the most primitive hardware circuit implementation of the physical keyboard. Figure 1 The keyboard design is realized in this way, because each key requires a wire harness. Taking 4 keys as an example, we will eventually need 4 wire harnesses. If 6 keys are needed, 6 wire harnesses are needed. From this point of view, it can be found that the wire harnesses are indeed very large.

[0004] Figure 2 It is a way to optimize the most original hardware circuit. Figure 2 The implementation principle of the keyboard design is: GPIO1 and GPIO2 are used as output signals, and GPIO3 and GPIO4 are used as input signals. GPIO1, GPIO2 and GPIO3, GPIO4 form a 2 by 2 matrix. The implementation principle is as follows: GPIO1 and GPIO2 output low level in turn. GPIO3 and GPIO4 are used as input ports to monitor whether the key is pressed. When a key is pressed, for example, when function key 1 is pressed, it is GPIO1's turn to output low level at the same time, and the key function will be triggered at the GPIO3 port. For another example, when function key 4 is pressed, it is GPIO2's turn to output low level at the same time, and the key function will be triggered at the GPIO4 port. Similarly, the press events of function keys 2 and 3 can be obtained. One thing to note here is that the time we press a key is relatively long, which will reach more than 50mS. Then as long as the frequency of GPIO1 and GPIO2's output in turn is greater than this time, the event of pressing the key will be detected. For example, if we set GPIO1 and GPIO2 to output low level alternately every 10mS, then within a pressing cycle of 50mS, the output of GPIO1 and GPIO2 will be detected 2 to 3 times, which can ensure effective detection.

[0005] At the same time, this implementation method has another feature. Because its implementation method is matrix implementation, that is, one group of GPIO as output and one group of GPIO as input, when the number of keys is more than 4, the number of harnesses will be significantly larger than Figure 1 For example, if we want to realize the function of 6 buttons, we can use 2 GPIO as output and 3 GPIO as input to form a 2 times 3 matrix, which only requires 5 wire harnesses, less than Figure 1 If 12 buttons are to be implemented, a 3x4 matrix can be used, which means that 12 wiring harnesses are not required, but only 7 wiring harnesses are needed. However, even so, there are still a lot of wiring harnesses, and the number of wiring harnesses cannot be effectively reduced.

[0006] Figure 3 This is a very common method in the current AR industry, which is to use a touchpad. Figure 3 As can be seen from the figure, the number of wiring harnesses has been reduced to 2. It can be said that the number has been reduced a lot. However, as described above, the touchpad also has its very bad defects: if there is water on the surface of the touchpad, the touch will fail; the functions that the touchpad can achieve are too limited, and can only achieve the functions of one or two buttons; the phenomenon of false triggering of the touchpad is very common, and the performance is unstable; if the hands are dirty or the person is wearing gloves, the touchpad will lose its function. Utility Model Content

[0007] The purpose of the utility model is to provide a hardware circuit of physical buttons applied to AR wearable products to solve the problems in the prior art.

[0008] To achieve the above-mentioned purpose, the utility model provides the following technical solution: a hardware circuit of a physical button applied to an AR wearable product, comprising a central processing unit and an ADC, wherein the central processing unit is connected to the ADC, and a plurality of resistors are connected in parallel to the pins of the ADC, and the plurality of resistors are grounded through buttons respectively.

[0009] Preferably, there are four resistors in total, and the four resistors correspond to four buttons.

[0010] Preferably, the resistance values ​​of the four resistors are 2.4K, 5.6K, 10K and 16K respectively.

[0011] Compared with the prior art, the beneficial effects of the utility model are:

[0012] The number of wiring harnesses for buttons can be reduced from several or two to just one, thereby maximizing the space available for transmission harnesses and providing technical support for wearable products in terms of appearance design, portability, weight, etc.

[0013] This application can be applied to wearable products that have very high requirements on the thickness of wire harnesses, such as AR, VR, etc., and can effectively reduce the number of wire harnesses introduced by buttons; thus, in AR product applications, the temples can be thinner, or the transmission lines can be smaller, the whole machine can be lighter, the button experience can be better than the touchpad, and other advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0015] Figure 1 It is the first circuit diagram of the prior art;

[0016] Figure 2 It is the circuit diagram of the second type of prior art;

[0017] Figure 3 It is the circuit diagram of the third type of prior art;

[0018] Figure 4 It is a circuit diagram of the utility model. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model. Therefore, the following detailed description of the embodiments of the utility model provided in the drawings is not intended to limit the scope of the utility model for which protection is claimed, but merely represents selected embodiments of the utility model.

[0020] See also Figure 4 In an embodiment of the utility model, a hardware circuit for physical buttons applied to AR wearable products includes a central processing unit and an ADC. The central processing unit is connected to the ADC. A plurality of resistors are connected in parallel to the pins of the ADC, and the plurality of resistors are grounded through buttons respectively. There are four resistors in total, and the four resistors correspond to four buttons; the resistance values ​​of the four resistors are 2.4K, 5.6K, 10K and 16K respectively (due to this parallel design, each ADC voltage can be independent and can be configured to any voltage. In this way, the voltage difference can also be well controlled within a spacing of 0.2V. It should be noted that Figure 4The resistance values ​​of the resistors in the figure are the resistance values ​​of the resistors that can actually be purchased, such as 2.4K, 5.6K, etc. It is actually difficult to purchase a resistance value like 2.5K. Therefore, there will be a remainder in the ADC voltage).

[0021] The central processing unit (CPU) detects the voltage on this pin through the ADC pin.

[0022] When a key is pressed, the circuit of this key will be short-circuited to the ground. At this time, a current loop is formed. From the pull-up power supply 1.8V inside the CPU chip, it flows through the pull-up resistor inside the CPU (in this case, it is 20K, and each chip may be different), and then flows from the outside of the CPU through the resistor corresponding to the key to the ground. Thus, a voltage at the ADC pin can be obtained.

[0023] If the voltage obtained falls within a detection range, the key event corresponding to the detection range is triggered, thereby obtaining the instruction of pressing the key, and completing the key detection.

[0024] Figure 4 In the display, the button with function 2 is pressed.

[0025] Current flows from the 1.8V internal pull-up, through the 20K internal resistor and the 5.6K external resistor to ground.

[0026] According to the voltage division formula, the voltage of the ADC pin can be obtained as:

[0027] 1.8 / (20+5.6)*5.6=0.39(V)

[0028] 0.39V will fall within the voltage range we preset in the software, and key function 2 will be detected.

[0029] Outside the CPU, on the ADC pin, several resistors are connected in parallel and grounded through buttons.

[0030] We can adjust the final voltage divider value of the ADC pin by changing the resistance of the parallel resistor. And it will not affect the ADC voltage divider values ​​of other buttons. This method can make our circuit more flexible to configure the newly added buttons and the voltage difference between each ADC voltage. It is more convenient for us to apply it flexibly.

[0031] The number of wire harnesses for buttons can be reduced from several or two to one, thereby maximizing the space for transmission wire harnesses and providing technical support for wearable products in terms of appearance design, portability, weight, etc.

[0032] Finally, it should be noted that the above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A hardware circuit for a physical button used in an AR wearable product, characterized in that: The invention comprises a central processing unit and an ADC. The central processing unit is connected to the ADC. A plurality of resistors are connected in parallel to the pins of the ADC. The plurality of resistors are grounded through buttons respectively.

2. According to claim 1, a hardware circuit of a physical button applied to an AR wearable product is characterized in that: There are four resistors in total, and the four resistors correspond to four buttons.

3. The hardware circuit of a physical button applied to an AR wearable product according to claim 2, characterized in that: The resistance values ​​of the four resistors are 2.4K, 5.6K, 10K and 16K respectively.

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