TW201109989A - Readout apparatus for current type touch panel - Google Patents

Abstract

A readout apparatus for current type touch panel is provided. The readout apparatus includes a current-to-voltage converter, a voltage gain unit and an analog-to-digital converter (ADC). The current-to-voltage converter converts a sensing current of the current type touch panel to a sensing voltage. An input end of the voltage gain unit couples to an output end of the current-to-voltage converter for receiving the sensing voltage. An input end of the ADC is coupled to an output end of the voltage gain unit. An output end of the ADC generates a digital code.

Description

201109989

^-0010-TW 31167twf.doc/n VI. Description of the Invention: [Technical Field] The present invention relates to a touch splicing, current type touch panel reading device. [Prior Art]

With the rapid development of electronic technology and the universalization of wireless communication and networks, various electronic devices have gradually become a tool for students. However, the common input and output (input/〇utpm, i/〇) interface, such as a keyboard or mouse, has a considerable degree of operation. In contrast, the touch panel is an intuitive and simple input and exit interface. Therefore, the touch panel is often used as a human-machine interface for human and electronic devices.

In particular, the touch panel can be classified into a resistive touch panel, an optical touch panel, an electric valley touch panel, and the like. According to the reading method, it can be classified into a current type touch panei and a charge type touch panel. Figure 1 illustrates a schematic diagram of a galvanic touch panel and a conventional readout circuit. The plurality of scan lines of the touch panel H0 are driven by a gate driver 130, and the plurality of sensing lines (sens〇r丨^) of the touch panel 11() are coupled to the read. Take circuit 140. The pixel layout of a conventional current touch panel is shown in FIG. Each of the pixels has a switch SW1 and a photo transistor PT. 201109989 ruvi-zwy-OO 10-TW 31167twf.doc/n When the bias voltage VBIAS is higher than the voltage of the node A, and the gate driver 130 turns on the switch SW1 via the scan line, due to the photonic crystal The PT is in a forward bias state such that a sense current Is flows to the sense line via the photo transistor PT and the SW1 switch. Among them, the intensity of the received light of the photo-electric crystal PT affects the magnitude of the sensing current Is. That is to say, the reading circuit 140 is used to detect the magnitude and difference of the sensing current Is on each sensing line, and it can be known whether there is a corresponding object in the touch panel 110 (that is, whether there is a foreign object touching the panel 110). The read circuit 140 sends the detection result to the image processing circuit 150 in digital form. The image processing circuit 150 determines the touch position based on the digital code provided by all of the read circuits 140. The conventional read circuit 140 converts the sense current is to a corresponding voltage using an integrator (ie, an operational amplifier mi and a feedback capacitor 142), and then an analog-to-digital converter (ADC) 143 The voltage is converted into a corresponding digital code, and finally the image processing circuit 150 determines the touch position based on the digital code. However, due to the read operation of the touch panel 110 using the integrator, if the sense current 15 is too large, the output of the combiner may reach saturation. In order to prevent the integrator 2 output from reaching saturation, the inductive capacitor (or integrating capacitor) of the integrator must increase the capacitance (ie increase the area). Since the mother-strip sensing lines of the touch panel each require an integrator, the wafer area of the read circuit will be considerable. 201109989

Y-0010-TW 31167twf.doc/n SUMMARY OF THE INVENTION The present invention provides a current touch panel reading device including a current-to-voltage converter, an ink gain unit, and an analogy to Analog-to-digital converter. The current to voltage conversion unit converts the sensing current of the current touch panel into a sensing voltage. An input of the voltage gain unit is coupled to an output of the current to voltage conversion unit to receive the sense voltage. The analog input to the digital converter is coupled to the output of the voltage gain unit, and the analog to the output of the digital converter produces a digital code. In an embodiment of the invention, the current to voltage conversion unit includes a resistor and a unity gain amplifier. The first end of the resistor receives the sense current, and the second end of the resistor is coupled to a reference voltage. The input of the unity gain amplifier is _ to the power_th-end' and the output of the unity gain amplifier is connected to the input of the dust gain unit.

- In the example, the above current to voltage conversion unit ^ resistance and current mirror. The first end of the resistor receives the first reference voltage, and the second end of the resistor touches the sensing current, and the current mirror is used to make the _ large or non-electrical device Inverting amplifier = two = benefit, such as anti (four) free use _ capacity, reach _ flow, so avoid 201109989

Hm-zuuy-uO 10-TW 31167twf.doc/n The above-mentioned features and advantages of the present invention are described in detail with reference to the accompanying drawings. Taking the optical current type _1 ) _1) 110 as an example, the description will be given to the panel (the turbid 〇 _ _ mail mode. However, the application touch panel of the reading device of the second invention can be based on the teachings of the present specification (4) (10) According to the embodiment of the invention, a current type touch panel read and drag. The reading device includes a current to voltage conversion, a voltage gain unit 22G, and an analog j flow to the voltage conversion unit 21G. The current touch panel power measurement/muscle Is is converted into the sensing voltage Vs. The input end of the voltage gain unit 22A is coupled to the output of the current to voltage conversion unit 21A to receive the sense voltage Vs. The voltage gain unit 220 is After the gain voltage Vs is gained, the corresponding gain voltage Vg is outputted to the analog converter 23. The voltage gain unit 220 can be an inverting amplifier (inverting amplifie) r) = 疋 non-inverting amplifier (Hon -inverting amplifier) The details of the analog-to-digital converter 230 are coupled to the output of the voltage gain unit 220. The analog-to-digital converter 230 converts the gain voltage Vg into a corresponding digital code Ds. The code Ds can be provided to a subsequent stage circuit (for example, the image processing circuit 15A) for further data processing to determine the touch position in the touch panel 110. y-0010-TW 31167twf.doc/n 201109989 Figure 3 is based on this The first embodiment of the invention describes a circuit diagram of a current touch panel item picking device. Referring to FIG. 3, the voltage gain unit 22 is implemented by a reverse phase enemy device. The inverting amplifier includes a resistor '22. The first end of the resistor 221 is the input end of the inverting amplifier, and the second end of the resistor 221 is coupled to the first input end of the operational amplifier 223. The first end of the resistor 222 and the first end The two ends are respectively coupled to the first input end and the output end of the operational amplifier 223. The second input end of the amplifier 223 receives the third reference voltage Vref, and the output of the amplifier 223 serves as the reverse phase. The output of the amplifier = in the embodiment, the first input terminal of the operational amplifier 223 is inverted (mvertmg input), and the second input terminal of the operational amplifier 223 is a non-inverting input (n〇n-inverting input). In addition, the application may determine the level of the reference voltage Vref according to the design requirements thereof, for example, setting the reference voltage Vref to the ground voltage (ie, 〇v) or setting the band-gap voltage. Or set to +5V, or set: He fixed the voltage. The present reference voltage Vfef is set to "half (ie, VDDA/2) of the VDDA level. The current-to-voltage conversion unit 21A of Figure 3 includes the resistor 21A. The first end of the resistor 211 receives the sensing current Ise The first end of the resistor 211 is coupled to the input end of the J-phase amplifier (ie, the first end of the resistor 221), and the second end of the electric-coupled = is coupled to a reference voltage (eg, a ground voltage). The sensing current Is is supplied through the resistor 211, so that the sensing voltage Vs is generated at the first end of the resistor u 1 . If the amount of change in the current Is is sensed, the change of the cup voltage Vg can be increased for this purpose. Resistance 201109989 nm-heart ~010-TW 3U67twf.doc/n 221 and 222 resistance values. The resistors 21^2^ and 222 shown in Figure 3 are fixed resistors. In order to respond to different characteristics of different touch panels, Those skilled in the art can implement the resistors 211, 221 and/or 222 with "variable resistors" depending on their design requirements. Fig. 4 is a circuit diagram showing a current type touch panel reading device according to a second embodiment of the present invention. This embodiment is similar to that of Fig. 3, so some of the contents will not be described again. The difference between the two is the current to voltage conversion unit 210. Referring to FIG. 4, the current-to-voltage conversion unit 21A includes a resistor 211 and a unity gain amplifier. Here, the unit amplifier is implemented by the operational amplifier 212. The first input end of the operational amplifier 212 is coupled to the first end of the resistor 211, the second input end of the operational amplifier 212 is coupled to the output end of the operational amplifier 212, and the output end of the operational amplifier 212 is coupled to the opposite phase. The input of the device (ie the first end of the resistor). In the present embodiment, the first-in terminal of the operational amplifier 212 is a non-inverting input terminal, and the second input terminal of the operational amplifying body 212 is an inverting input terminal. Since the unity gain amplifier is configured in the current to voltage converting unit 21, the load effect of the sensing voltage Vs can be avoided. If the amount of change in the sense current Is is small, in order to make the change of the gain can be distinguished, 'in addition to increasing the resistance values of the resistors 211 and 221 of the resistors 211 and 221 in FIG. 3 and FIG. 4, the voltage gain can also be obtained in the voltage gain unit (22). Multiple strings of inverting amplifiers are included in series to allow gain unit 22. The gain ratio is higher. BRIEF DESCRIPTION OF THE DRAWINGS A circuit diagram of the voltage benefit unit 220 of Fig. 2 is illustrated in accordance with a third embodiment of the present invention. Referring to FIG. 5, the inverting amplifier (voltage gain unit 22A) includes an inverting amplifying circuit 510-1~51〇_n^ these inverting amplifying circuits 510- 1 to 510-n are connected in series to form an amplifier string. An input end of the first inverting amplifying circuit 510-1 of the amplifier string is coupled to an output of the current to voltage converting unit 210 to receive the sensing voltage Vs, and the last two inverting amplifying circuits in the amplifier string The output of 51〇-n is coupled to the analog to digital input 230 input. For the implementation of the above-mentioned inverting amplifying circuit, reference may be made to the related description of the "inverting amplifier" in Fig. 3, and therefore it will not be described here. Since a plurality of inverting amplifiers (i.e., inverting amplifying circuits 510-1 to 5ι〇_η) are connected in series in the voltage gain unit 22G, the gain magnification of the electric dust gain unit 220 is improved. θ Figure 6 is a circuit diagram showing a current type touch panel reading device according to a fourth embodiment of the present invention. This embodiment is similar to that of Figure 3, so some of the content will not be described. The difference between the two is that FIG. 6 implements the aforementioned voltage gain unit 22 by non-inverting discharge. This non-inverting amplifier includes = amplifier 224, resistor 225 and resistor 226. The input of the operational amplifier 224 is reduced to the output of the current-to-voltage conversion unit 210 to sense the voltage Vs'. The output of the operational amplifier 224 outputs a gain voltage g analogy to the input of the digital converter 23A. The first end of the resistor 226 is connected to the second input of the differential amplifier 224, and the second terminal of the resistor 226 is charged to the voltage (e.g., ground voltage). The first end and the second end of the resistor 225 are lightly coupled to the second input and output of the operational amplifier 224. In the example, the first input terminal of the operational amplifier 224 is a non-inverting input I and the second input of the operational amplifier 224 is an inverting input terminal. In another embodiment, the combination of the voltage gain material 22() and the analog-to-bit conversion is shown in Fig. 6 and can be matched according to the design requirements (see Figure 17). Not shown). The present inventors can consider the design requirements, and the current to voltage conversion unit 21 of Figure 6. For example, in addition to the implementation of the current-to-voltage conversion unit 21A shown in FIG. 3, the current-to-voltage conversion unit MO can be implemented using a resistor and a current mirror. In the other embodiment, the non-inverting amplifier inside the voltage gain unit 22G includes non-inverting circuits. This age reverses the large circuit phase amplifier string. The input end of the first non-inverting amplifying circuit in the amplifier string is coupled to the current to the last non-inverting amplifying circuit of the power converting unit 21G, which is the analogy to digital conversion The input end of the device 23〇. For the implementation of the above amplifier string, reference may be made to w 5, that is, the 5 + inverting amplifying circuits 510-1 to 510·n may be replaced by a non-inverting amplifying circuit. Figure 7 is a circuit diagram showing the current-to-voltage conversion unit 210 of Figure 2 in accordance with a fifth embodiment of the present invention. Current to voltage conversion unit 210 includes a resistor 710 and a current mirror 720. The first terminal of the resistor 710 receives a first reference voltage (e.g., system voltage VDDA), and the second terminal of the resistor 710 is coupled to the input of the voltage gain unit 220. Here, the resistance 71 实现 is realized by a p-channel MOS transistor 711 to reduce the area of the resistor 71 〇 丨丨 σ. A first terminal (e.g., a source) of transistor 711 receives system voltage VDDA' and a second terminal (e.g., a drain) of transistor 711 is coupled to a control terminal (e.g., a gate) to an input of voltage gain unit 220. 201109989— 31167twf.doc/n The main current terminal of the current mirror 720 receives the sensing current Is, and the current terminal of the current mirror 72〇 is consumed to the second end of the resistor 710. By setting the current multiplying current of both the main current terminal and the servant current terminal of the current mirror 72, the current mirror 72 放大 can amplify the weak sensing current Is. This amplified sense current is converted to a sense voltage vs via a resistor 710. Thus, under the condition that the strong light and the weak light illuminate the photoelectric crystal PT, the variation range of the obtained sensing voltage Vs can be increased, so that the recognition degree of the sensing voltage Vs can be increased. The sense voltage Vs is then secondarily amplified by an inverting amplifier/non-inverting amplifier (i.e., voltage gain unit 22A) to obtain a gain voltage Vg' for subsequent processing. Here, the current mirror 720 includes a first transistor 721 and a second transistor 722. This embodiment implements crystals 721 and 722 in an N-channel gold oxide half (NM0S) transistor. The first end (e.g., the drain) of the transistor 721 acts as the main current terminal of the electric mirror 720. The second end (e.g., the source) of the transistor 721 is connected to the second reference voltage (e.g., ground voltage), and the transistor 721. The control terminal (eg, the gate) is coupled to the first end of the transistor 721. The first end of the transistor 722 serves as the servant current terminal of the current mirror 720, the second end of the transistor 722 receives the second reference voltage (ground voltage)' and the control terminal of the transistor 722 is coupled to the control terminal of the transistor 721. By determining the appearance ratio of the transistors 721 and 722, the current magnification of both the main current terminal and the current terminal of the current mirror 720 can be set. Figure 8 is a circuit diagram showing the current-to-voltage conversion unit 210 of Figure 2 in accordance with a sixth embodiment of the present invention. This embodiment is similar to that of Fig. 7, so the details will not be described again. The difference between the two is that Fig. 8 uses a current mirror 730 instead of the aforementioned current mirror 720. The current mirror 730 includes a first electric crystal 11 201109989 nm.zuvy^OlO-TW 31167twf.doc/n 7t a second transistor 732, a third transistor 733, and a 734th. The first end of the transistor 731 (e.g., no pole == four transistor terminals) and the control terminal of the transistor 731 (e.g., the first end of the main 73J of the transistor 730. the first of the transistor 732) is coupled To the servant current terminal of transistor 730, and the terminal of transistor 732 =) as the other control terminal of the current mirror transistor. The transistor 733 is connected to the second end of the crystal m (for example, no 峨W, for example, the source) receives the reference key (for example, the second control end of the body 733 (for example, the interpole) scales to electricity. The first end of the crystal 733 734 (eg, not connected to the transistor. The source of the transistor), the second end of the second body 732 of the transistor 734 (eg, voltage), and the transistor 734 ^) Receive reference voltage (grounded control terminal. Control (4) (for example, gate) is coupled to transistor 733. When switch SW1 of line control panel 11G is off, the sense line on the sense voltage of the 230th gain voltage & When the measured _milk is turned on, the voltage conversion unit-two-two device is converted into a gain voltage two-digit value to be taken out. The wire ί ^ Γ will be the difference value of the gain voltage Vg. The value and the first digit value of the first strong and the weak light illuminate the photoelectric crystal ΡΤ generated by the sensing electricity 12 y-0010-TW 31167t\vf.doc/n 201109989 flow Is will be different, so the above difference will also have The position of the touch is not mentioned. Although the present invention has been disclosed above by way of example, it is not intended to limit the present invention. It is to be understood that the scope of the invention is defined by the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a current type touch panel and a conventional read circuit (this is a circuit). FIG. 2 is a circuit diagram showing a current type touch panel reading device according to an embodiment of the invention. 3 is a circuit diagram of a current type touch panel reading device according to a first embodiment of the present invention. FIG. 4 is a circuit diagram of a current type touch panel item picking device according to a second embodiment of the present invention. Fig. 5 is a circuit diagram showing the voltage gain unit of Fig. 2 according to a third embodiment of the present invention. Fig. 6 is a circuit diagram showing a current type touch panel reading device according to a fourth embodiment of the present invention. Figure 7 is a circuit diagram showing the current-to-voltage conversion unit of Figure 2 in accordance with a fifth embodiment of the present invention. Figure 8 is a sixth embodiment of the present invention. 2 Circuit diagram of current to voltage conversion unit 13 201109989 HM-2Uuy-u010-TW 31167twf.doc/n [Main component symbol description] 110: Touch panel 130: Gate driver 14Ό, 200: Read circuit - - ', 141, 212, 223, 224: operational amplifier 142: feedback capacitors 143, 230: analog to digital converter 150: image processing circuit

210: current to voltage conversion unit I 220: voltage gain unit 211, 221, 222, 225, 226, 710: resistors 510-1, 510-n: inverting amplifying circuit 711: P channel MOS semi-transistor 720, 730 : Current mirrors 721~722, 731~734: N-channel MOS semi-transistor Ds: digital code

Is : Sensing current PT : Photoelectric crystal SW1 : Switch VBIAS : Bias voltage

Vg: gain voltage

Vs : sensing voltage 14

Claims (1)

^-〇〇10-TW 31167tvvf.doc/n 201109989 VII. Patent application scope: 1. A readout of a current-type touch panel, including · current-to-voltage conversion unit, using Christine sensing current to be converted to - Sensing voltage; "a control panel-voltage gain unit, whose input terminal is connected to the wheel-out terminal of the unit to receive the sensing voltage; and U~ to power (four) for 2-bit recording terminal tin (four) connected to the 兀The output end, the analogy to the digital converter's transmission - prematurely defeated as the towel, please paste the current type touch H of the first device, wherein the current to voltage conversion unit comprises: the plate of the resistance, the first One end receives the sensing current, and one end of the towel is lightly connected to the first to the reference voltage of the voltage gain unit. The input device i of the current touch panel of the first aspect of the present invention, wherein the current-to-voltage conversion unit comprises: a resistor, the first end of which receives the sensing current, and The resistor is coupled to a reference voltage; and, in the early morning, the gain amplifier has its input lightly coupled to the first of the resistors, and the output terminal of the unity gain amplifier is coupled to the input of the voltage gain unit. For example, please read the reading of the current touch panel of the patent class 3, and the unity gain amplifier includes an operational amplifier, and the first input of the yr and the sigmoid is used as the wheel of the unity gain amplifier. In the end, the second round of the amplifier is lightly connected to the output of the operational amplifier 15 201109989 WM-zuuy-uOlO-TW 31167twf.doc/n = the end and the r is called the round end as the unit gain The reading device of the current touch panel of the first embodiment of the present invention, the current-to-voltage conversion unit includes: the current of the resistor and the current mirror-resistance The terminal receiving_first-reference voltage is connected to the input end of the electric waste gain unit; and the current mirror's main current terminal receives the sensing current and is coupled to the second end of the resistor. Taking the second reading of the current touch panel as described in item 5 as a transistor, the first end of the transistor is received; the second end of the gain single crystal is connected to the control terminal to the current of the electrical pickup The touch panel reads the first ::::1 曰ϊ 'the first end serves as the main current end of the current mirror, 曰=the second end of the electric Japanese body receives the second reference voltage, and the first The control end of the electric male body is coupled to the 苐-end of the first transistor, and the first: the first end thereof serves as a servant current end of the current mirror, and the control of the crystal is to the first transistor The second electrical reading 4 turns over the reading mode of the green sensitive panel of the seventh item to a ground plane. Μ弟-参16 201109989 7-0010-TW 31167twf.doc/n Take two = Mirror: the read-first-transistor of the current touch panel, the first one as the main current end of the current mirror, and The control terminal of the first transistor is coupled to the terminal of the first transistor; the second and the second and the second transistor of the second and second transistors have a first end serving as a current of the current mirror a second transistor having a control terminal _ to a control terminal of the first transistor; a second transistor having a first terminal coupled to the first transistor terminal and a second transistor Receiving a second reference voltage, the control terminal of the second transistor is coupled to the first end of the third transistor, the fourth transistor, and the first end thereof is connected to the second transistor end, the fourth transistor The second terminal receives the second reference voltage, and the control terminal of the fourth transistor is coupled to the control of the third transistor. The current mode=panel (four) device is as described in the first item of the patent application. - Anti-reduction |||Achieve it. 11. The current touch panel according to claim 1G of the patent, wherein the inverting amplifier comprises: a second resistor having a first end as an input of the inverting amplifier; an operational amplifier The first input end is coupled to the first end of the first resistor, the second input end of the operational amplifier receives a first reference voltage, and the output end of the operational amplifier serves as an output end of the inverting amplifier; The first end and the second end of the second resistor are respectively coupled to the first input end and the round output end of the computing device. 12. The current touch panel red reading device according to claim 1, wherein the inverting amplifier comprises a plurality of inverting amplifying circuits, #17 201109989 ^ ... aw „Jl〇-TW 31l67twf.doc The inverting amplifying circuits of /n are connected in series to form an amplifier string, and an input end of the first inverting amplifying circuit of the amplifier string is coupled to an output of the current to voltage converting unit, and the amplifier The output of the last inverting amplifying circuit in the string is coupled to the input of the analog to digital converter. The reading device of the current touch panel according to claim 1, wherein the voltage gain is The unit is implemented by a non-inverting amplifier. The reading device of the current touch panel of claim 13, wherein the non-inverting amplifier comprises: The first input of the first amplifier serves as the input of the non-inverting amplifier, and the output of the operational amplifier serves as the output of the non-inverting amplifier; a first resistor of the first resistor is coupled to the operational amplifier a second input %, the second end of the first resistor receives a reference voltage; and a second resistor, the first end and the second end are respectively coupled to the second input end and the output end of the operational amplifier. ^ 15. The current touch panel of claim 13 The reading device 'the non-inverting amplifier A includes a plurality of non-inverting amplifying circuits, wherein the non-inverting amplifying circuits are connected in series to form an amplifier string, and the first non-reverse in the amplifying string The input of the phase amplifying circuit is coupled to the output of the current to the voltage converting unit, and the output of the last non-inverting amplifying circuit of the amplifier string is coupled to the analog to the input of the converter. Turn 18