Signal rapid scanning and reading circuit system suitable for touch sensor

Abstract

The invention provides a signal fast scanning and reading circuit system suitable for a touch sensor. The system comprises a 16 * 16 sensing capacitor array used for simulating pressure information; the 16 column parallel capacitance digital conversion channels are used for realizing conversion from capacitance signals to digital signals; the multiplexer module is used for controlling a capacitor to be connected to the capacitance digital conversion channel; the 4-16 decoders control switches of the multiplexers, so that the capacitors are gated column by column; and the time sequence control module is used for generating a working time sequence of the circuit. Meanwhile, each capacitance digital conversion channel comprises a capacitance voltage conversion circuit, so that conversion from a capacitance signal to a voltage signal is realized; the circulating analog-to-digital converter is used for converting the voltage into a digital signal; and the parallel-serial conversion interface circuit converts the parallel digital output of the analog-to-digital converter into serial digital output, so that the number of chip pins is reduced, and the integration level is improved. The invention has the advantages of high integration level and fast conversion speed.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit design, and in particular to an array scanning and readout circuit design of a capacitive tactile sensor, which is particularly suitable for a tactile sensing system with a large array and a high refresh rate. Background Art

[0002] With the development of flexible electronics and intelligent robotics technology, the demand for tactile sensors in the fields of human-computer interaction, medical monitoring, etc. is increasing. As a key component for robots to interact with the external environment, tactile sensors need to convert pressure information into processable digital signals, which requires a sensor signal readout circuit to achieve this. Traditional tactile sensor signal readout circuits are mostly implemented using board-level circuits, which have problems such as low integration, high power consumption, and slow array scanning speed. Currently, tactile sensor signal readout circuits can be divided into resistive, capacitive, and piezoelectric readout methods. Among them, the capacitive readout circuit has the advantages of a large dynamic range, high sensitivity, and fast response speed, and has good application prospects in human-computer interaction. However, there is currently a lack of a sensor signal readout chip with high integration and fast readout speed. The present invention realizes a signal rapid scanning and readout circuit system for a capacitive tactile sensor, which can realize rapid scanning and readout of the sensing unit on the capacitive tactile sensor and has a high degree of integration. Summary of the Invention

[0003] The present invention provides a highly integrated, high-speed capacitive tactile sensor signal scanning and readout circuit and method, which achieves fast and stable capacitive signal digital conversion by optimizing circuit architecture and timing control.

[0004] The object of the present invention is achieved by the following measures:

[0005] 1. A signal rapid scanning and readout circuit system suitable for a tactile sensor, characterized in that it comprises a 16×16 sensing capacitor array (100), a multiplexer (101), a 4-16 decoder (102), a timing control module (103) and 16 capacitance-to-digital conversion circuits (104); wherein each capacitance-to-digital conversion circuit (104) comprises a capacitance-to-voltage conversion circuit (105), a cyclic analog-to-digital converter (106) and a parallel-to-serial conversion circuit (107); each column of the capacitance of the 16×16 sensing capacitor array (100) is connected to the multiplexer (101) through plate multiplexing, and the 4-16 decoder (102) outputs The 16-way control signal Row[16:1] is connected to the multiplexer (101) to control its selection switch; the four control signals A<3:0> generated by the timing control module (103) control the 4-16 decoder (102), and the control signals S1 and S2 are generated to respectively control the operation of the capacitance voltage conversion circuit (105) and the cyclic analog-to-digital converter (106) in the 16 capacitance-to-digital conversion circuits (104); the capacitance voltage conversion circuit (105) converts the capacitance signal into a voltage signal and sends it to the analog-to-digital converter (106) for processing into a parallel digital signal for output; the parallel-to-serial conversion interface circuit (107) converts the parallel digital output into a serial digital output.

[0006] The 16×16 sensing capacitor array (100) is an external chip module for simulating sensor pressure changes; the 16×16 sensing capacitor array (100) adopts a plate multiplexing connection method, that is, the upper plates of each row of capacitors are short-circuited together and respectively connected to the capacitor voltage conversion circuits (105) in 16 capacitor-to-digital conversion circuits (104), and the lower plates of each column of capacitors are short-circuited together and respectively connected to the selection switches of the multiplexer (101); the output of the multiplexer (101) is connected to the capacitor voltage conversion circuits (105) in the 16 capacitor-to-digital conversion circuits (104); and the multiplexer (101) is controlled by the output signal Row[16:1] of the 4-16 decoder (102).

[0007] The timing control module (103) generates four control signals A<3:0> for the 4-16 decoder (102), a control signal S1 for the capacitor-voltage conversion circuit (105), and a control signal S3 for the cyclic analog-to-digital converter (106).

[0008] The 16 capacitance-to-digital conversion circuits (104) convert capacitance signals into 10-bit digital signals Dout (9:0) which are output one by one in a parallel working mode.

[0009] Figure 1The present invention is a block diagram of a capacitive touch sensor array readout circuit system. A 16×16 sensing capacitor array (100) converts capacitance signals into digital signals through 16 columns of parallel capacitance-to-digital conversion circuits (104). Each column integrates a capacitance-to-voltage conversion circuit (105) and a cyclic analog-to-digital converter (106) to implement the capacitance-voltage-to-digital conversion process.

[0010] Figure 2 The circuit operation timing diagram is shown, wherein Row1-Row16 are the switch control signals of the multiplexer (101), CVC represents the capacitor-voltage conversion process, and ADC represents the analog-to-digital conversion process. A pipeline scanning timing is adopted to enable the capacitor-voltage conversion circuit (105) and the cyclic analog-to-digital converter (106) to work alternately.

[0011] The present invention converts the parallel output of an analog-to-digital converter into a serial output and employs a capacitor array connection method with plate reuse. This reduces the number of chip pins, reduces chip area, improves chip integration, and lowers manufacturing costs. Furthermore, the present invention's scanning circuit architecture improves the refresh rate of the sensor array, making it suitable for signal scanning and readout of large arrays of capacitive touch sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The block diagram of the signal scanning and readout circuit system of the capacitive touch sensor;

[0013] Figure 2 It is the working timing diagram of the circuit;

[0014] Among them: 100 is a 16×16 sensor capacitor array; 101 is a multiplexer; 102 is a 4-16 decoder; 103 is a timing control module; 104 is a capacitance-to-digital conversion circuit; 105 is a capacitance-to-voltage conversion module; 106 is a cyclic analog-to-digital converter; and 107 is a parallel-to-serial conversion interface circuit. DETAILED DESCRIPTION

[0015] According to the aforementioned invention, a circuit structure was constructed in Cadence by applying the 0.18 μm process provided by Semiconductor Manufacturing International Corporation (SMIC). The feasibility of the design of the above structure was verified by simulation.

[0016] Through the mutual control of the timing control module (103), the 4-16 decoder (102) and the multiplexer (101), the selection switches Row1-Row16 of the multiplexer are opened one by one, and the capacitors of the 16×16 sensing capacitor array (100) are connected to the 16 capacitor digital conversion circuits (104) column by column to complete the conversion of the capacitor signal to the digital signal. Finally, the 256 sensing capacitors are converted into 256 10-bit serial digital outputs.

[0017] 16 capacitance-to-digital conversion circuit (104) channels, each channel includes a capacitance-to-voltage conversion circuit (105), a 10-bit cyclic analog-to-digital converter (106), and a parallel-to-serial conversion interface circuit (107). The capacitance-to-voltage conversion circuit (105) realizes the conversion of capacitance signals into voltage signals, the 10-bit cyclic analog-to-digital converter (106) realizes the conversion of voltage signals into 10-bit parallel digital outputs, and the parallel-to-serial conversion interface circuit (107) realizes the conversion of parallel digital outputs into serial digital outputs.

[0018] In order to improve the integration of the circuit, the 16×16 sensing capacitor array (101) uses a plate multiplexing connection method to reduce the number of pins connected to the chip, thereby reducing the chip area. At the same time, the parallel-to-serial conversion interface circuit (107) converts parallel digital output into serial digital output, reducing the number of digital output ports of the chip and further reducing the number of chip pins.

[0019] In order to improve the refresh rate of the 16×16 sensing capacitor array (100), the capacitor voltage conversion process and the analog-to-digital conversion process adopt a pipeline working mode, such as Figure 2 As shown. The pipeline operation sequence enables the capacitor voltage conversion circuit (105) and the cyclic analog-to-digital converter (106) to work alternately. When the Nth column performs analog-to-digital conversion, the N+1th column synchronously performs capacitor voltage conversion, wherein the average time to complete one capacitor digital conversion is:

[0020] t CDC =max{t CVC ,t ADC}

[0021] where t CDC is the time to complete one capacitance-to-digital conversion, t CVC is the time to complete one capacitor voltage conversion, t ADC This is the time required to complete one analog-to-digital conversion. This reduces the conversion time of the entire array and increases the array refresh rate.

[0022] Therefore, the array readout circuit of the capacitive sensor built with the above structure can realize rapid scanning and reading of signals, while reducing the chip area and saving chip manufacturing costs, and can be applied to the field of tactile perception of robots.

Claims

1. A signal fast scanning and readout circuit system suitable for a tactile sensor, characterized in that: The invention comprises a 16×16 sensing capacitor array (100), a multiplexer (101), a 4-16 decoder (102), a timing control module (103) and 16 capacitance-to-digital conversion circuits (104); wherein each capacitance-to-digital conversion circuit (104) comprises a capacitance-to-voltage conversion circuit (105), a cyclic analog-to-digital converter (106) and a parallel-to-serial conversion circuit (107); each column of capacitance of the 16×16 sensing capacitor array (100) is connected to the multiplexer (101) through plate multiplexing, and the 16-way control signal Row[16:1] output by the 4-16 decoder (102) is output. The device is connected to a multiplexer (101) to control its selection switch; the four control signals A<3:0> generated by the timing control module (103) control the 4-16 decoder (102), and simultaneously generates control signals S1 and S2 to respectively control the operation of the capacitance voltage conversion circuit (105) and the cyclic analog-to-digital converter (106) in the 16 capacitance-to-digital conversion circuits (104); the capacitance voltage conversion circuit (105) converts the capacitance signal into a voltage signal and sends it to the analog-to-digital converter (106) for processing into a parallel digital signal for output; and the parallel-to-serial conversion interface circuit (107) converts the parallel digital output into a serial digital output.

2. The tactile sensor signal rapid scanning and readout circuit system according to claim 1, characterized in that: The 16×16 sensing capacitor array (100) is an external chip module for simulating sensor pressure changes; the 16×16 sensing capacitor array (100) adopts a plate multiplexing connection method, that is, the upper plates of each row of capacitors are short-circuited together and respectively connected to the capacitor voltage conversion circuits (105) in 16 capacitor-to-digital conversion circuits (104), and the lower plates of each column of capacitors are short-circuited together and respectively connected to the selection switches of the multiplexer (101); the output of the multiplexer (101) is connected to the capacitor voltage conversion circuits (105) in the 16 capacitor-to-digital conversion circuits (104); and the multiplexer (101) is controlled by the output signal Row[16:1] of the 4-16 decoder (102).

3. The tactile sensor signal rapid scanning and readout circuit system according to claim 1, characterized in that: The timing control module (103) generates four control signals A<3:0> for the 4-16 decoder (102), a control signal S1 for the capacitor-voltage conversion circuit (105), and a control signal S3 for the cyclic analog-to-digital converter (106).

4. The tactile sensor signal rapid scanning and readout circuit system according to claim 1, characterized in that: The 16 capacitance-to-digital conversion circuits (104) convert capacitance signals into 10-bit digital signals Dout (9:0) which are output one by one in a parallel working mode.

Images