CN105824185A - X-ray sensing panel - Google Patents

Abstract

The invention provides an X-ray sensing panel, which comprises a plurality of data lines, a plurality of scanning lines, a plurality of pixel elements, a plurality of integrator circuits and a plurality of compensation circuits. The pixel elements are configured into a matrix array, and are coupled to the corresponding data lines and the corresponding scanning lines for generating a sensing signal. The integrator circuits comprise an operational amplifier, and an inverting input end of the operational amplifier is coupled to the corresponding data line and used for receiving the sensing signal through the data line. The compensation circuits are coupled to a non-inverting input terminal of the corresponding operational amplifier for providing a compensation signal to the corresponding integrator circuit.

Description

X-ray sensing panel

technical field

The invention relates to an X-ray sensing panel, in particular to an X-ray sensing panel capable of eliminating noise.

Background technique

Traditional X-ray medical equipment uses negative film for interpretation and storage. In order to provide better image quality and storage methods, digital X-ray medical equipment can be used. The digital X-ray medical equipment uses an X-ray sensing panel to sense X-rays. However, in the process of digitizing the analog signal, a lot of noise will be generated. For example, the sensor and reading IC inside the X-ray sensing panel will also generate noise, which will affect the interpretation. In order to provide more precise medical equipment, it is necessary to provide a noise-canceling X-ray panel.

Contents of the invention

The invention relates to an X-ray sensing panel, which can eliminate noise by means of a compensating circuit to achieve more accurate X-ray sensing results.

According to an embodiment of the present invention, an X-ray sensing panel is provided. The X-ray sensing panel includes multiple data lines, multiple scan lines, multiple pixel elements, multiple integrator circuits and multiple compensation circuits. A plurality of pixel elements are arranged in a matrix array, and these pixel elements are coupled to corresponding data lines and scan lines for generating a sensing signal. These integrator circuits include an operational amplifier, and an inverting input terminal of the operational amplifier is coupled to a corresponding data line for receiving sensing signals through the data line. These compensation circuits are coupled to a non-inverting input terminal of a corresponding operational amplifier for providing a compensation signal to a corresponding integrator circuit.

Description of drawings

In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

FIG. 1 is a block diagram of an X-ray sensing panel 100 according to an embodiment.

FIG. 2 is a circuit diagram of an X-ray sensor structure in the X-ray sensing panel 100 according to an embodiment.

FIG. 3 is an equivalent circuit diagram of a transistor TFT according to an embodiment.

FIG. 4 is a timing diagram of a compensation circuit according to an embodiment.

The component numbers in the figure are as follows:

100: X-ray sensing panel

110: matrix array

120: Scanning drive circuit

130 ₁ ~ 130 _m : Compensation circuit

I ₁ ~I _m : Integrator circuit

D ₁ ~D _m : data line

G ₁ ~G _n : Scanning lines

P(x,y): pixel element

140: scintillator

TFT: Transistor

S _D , S _E , S _comp , S _O : signal

PD: Photodiode

Op: operational amplifier

Vbias, Vd, Vg, Vgh, Vgh, Vgl, V _TFTOut , V+, V-, ΔV1, ΔV2: Voltage

C1: capacitance

Vref: AC voltage source

S1: switch

t _r : Rising period

t _f : Falling period

detailed description

Please refer to FIG. 1 , which is a block diagram of an X-ray sensing panel 100 according to an embodiment. The X-ray sensing panel 100 includes a plurality of data lines D1-Dm, a plurality of scanning lines G ₁ -G _n , a plurality of pixel elements P(x,y), a plurality of integrator circuits I ₁ -I _m and a plurality of compensation Circuit 130 ₁ to 130 _m . A plurality of pixel elements P(x,y) are arranged in a matrix array 110 , and the pixel elements P(x,y) are coupled to corresponding data lines D _x and scan lines G _y . In this embodiment, the pixel element P(x,y) is used to generate a sensing signal S _E . The integrator circuit 130x includes an operational amplifier Op (shown in FIG. 2 ), and an inverting input terminal (V-) of the operational amplifier Op is coupled to the corresponding data line _Dx for receiving the sense signal via the data line Dx. Signal S _E . The compensation circuit 130x is coupled to a non-inverting input terminal (V+) of the corresponding operational amplifier Op for providing a compensation signal S _comp to the corresponding integrator circuit Ix. The X-ray sensing panel 100 may further include a scan driving circuit 120 for providing scan signals S _G to the pixel elements through the scan lines G ₁ -G _n .

FIG. 2 is a circuit diagram of an X-ray sensor structure in the X-ray sensing panel 100 according to an embodiment. In this embodiment, the X-ray sensing panel 100 converts the X-ray signal into a visible light signal S _O through a scintillator 140 . These pixel elements all include a photodiode PD and a transistor TFT. The photodiode PD receives the visible light signal S _O and converts it into a sensing signal S _E of an electric signal. The magnitude of the sensing signal S _E corresponds to the light intensity of X-rays received in this area. The transistor TFT has a first terminal, a second terminal and a control terminal. A first terminal of the transistor TFT is coupled to the photodiode PD, and a second terminal of the transistor TFT is coupled to an inverting input terminal (V-) of the integrator circuit. The control end of the transistor TFT is used for receiving the scan signal S _G , and is turned on according to a high potential scan signal to transmit the sensing signal _SE to the integrator circuit 130 . The integrator circuit 130 _x can read the sensing signal S _E of the pixel elements of a row of data lines (eg, D _x ). The scan driving circuit 120 transmits a scan signal S _G to a column of scan lines (such as G _y ) so that all the integrator circuits 130 ₁ -130 _m respectively receive the sensing signals S _E of all the pixel elements of the column. After receiving the sensing signal, the integrator circuit converts the electrical signal into a digital signal for subsequent data processing by other circuits, such as generating X-ray images or slides, and the like.

However, when the scan signal S _G controls the transistor TFT to be turned on or off, the parasitic capacitance of the transistor will generate noise, which will cause errors in the sensing signal and affect subsequent interpretation. Therefore, in this embodiment, a compensation circuit 130 _X is coupled to a non-inverting input terminal (V+) of the operational amplifier Op of the integrator circuit I _X for providing a compensation signal S _comp to the integrator circuit I _X . In one embodiment, the compensation circuit includes a capacitor C1, an AC voltage source Vref, and a switch S1. The capacitor C1 is coupled to the non-inverting input terminal (V+) of the operational amplifier Op. The AC voltage source Vref is coupled to the C1 capacitor. The switch S1 is coupled between the non-inverting input terminal (V+) of the operational amplifier Op and the AC voltage source Vref. However, the present invention is not limited thereto, and the compensation circuit can be implemented with other circuit structures.

Please refer to FIG. 3 and FIG. 4 to illustrate the implementation of the compensation circuit of the present invention. FIG. 3 is an equivalent circuit diagram of a transistor TFT according to an embodiment. The control terminal of the transistor TFT is used for receiving the scanning signal and has a voltage Vg. The first terminal of the transistor TFT, which is defined as the drain terminal here, is coupled to the photodiode PD and has a voltage Vpd. The second terminal of the transistor TFT, which is defined as the source terminal here, is coupled to an inverting input terminal (V-) of the integrator circuit, and has a voltage Vd. The photodiode PD receives a voltage Vbias and has a parasitic capacitance Cpd. There is a parasitic capacitance Cgs between the control terminal and the first terminal (drain terminal) of the transistor TFT. There is a parasitic capacitance Cgd between the control terminal and the second terminal (source terminal) of the transistor TFT. When the transistor TFT is turned on or off, these parasitic capacitances will generate an error voltage at the output of the transistor TFT. This error voltage will cause the charge read by the integrator circuit to be different from the charge generated by the photodiode, thereby affecting X-ray sensitivity. The accuracy of the measured value will affect the judgment result of the image.

FIG. 4 is a timing diagram of a compensation circuit according to an embodiment. During a rising period t _r when the scan signal S _G changes from a low potential Vgl to a high potential Vgh, due to the influence of the parasitic capacitance of the transistor TFT, the output V _TFTOut of the transistor TFT will generate a positive error voltage +ΔV1. Similarly, during a falling period t _f when the scanning signal S _G changes from a high potential Vgh to a low potential Vgl, due to the influence of the parasitic capacitance of the transistor TFT, the output V _TFTOut of the transistor TFT will generate a negative error voltage -ΔV2 .

Therefore, in order to eliminate the error voltage, during a rising period t _r of the scan signal S _G changing from a low potential Vgl to a high potential Vgh, the switch S1 of the compensation circuit is turned on to provide a polarity opposite to the error voltage +ΔV1 A negative voltage compensation signal -ΔV1. Similarly, during a falling period t _f when the scanning signal S _G changes from a high potential Vgh to a low potential Vgl, the switch S1 of the compensation circuit is turned on to provide a forward voltage opposite to the error voltage -ΔV2 Compensation signal +ΔV2.

The error voltages ΔV1 and ΔV2 are determined by the following formula:

$\mathrm{<span\; class="notranslate">\; \&Delta;V</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Vgh</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; Cgd</span>}}{\mathrm{<span\; class="notranslate">\; Cgd</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Cgd</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Vbias</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; Cpd</span>}}{\mathrm{<span\; class="notranslate">\; Cgd</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Cpd</span>}}$

$\mathrm{<span\; class="notranslate">\; \&Delta;V</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; vgl</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; Cgd</span>}}{\mathrm{<span\; class="notranslate">\; Cgd</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Cgd</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Vbias</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; Cpd</span>}}{\mathrm{<span\; class="notranslate">\; Cgd</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Cpd</span>}}$

As shown in FIG. 2 , the compensation circuit includes a capacitor C1 , an AC voltage source Vref and a switch S1 . By turning on the switch S1 during a rising period or a falling period when the potential of the scanning signal changes, the compensation circuit provides a voltage of the opposite polarity, because Q=C1*Vref=C1*ΔV=Cpd*Vpd, and the polarity can be generated Opposite charges to cancel ΔV1 and ΔV2.

In addition, during periods other than a rising period t _r and a falling period t _f when the potential of the scanning signal changes, the switch S1 is closed, and the compensation circuit provides a compensation signal of a DC bias voltage V _offset as an offset voltage (offsetvoltage) of the operational amplifier. . Wherein, the capacitance value of the capacitor C1 and the voltage value of the AC voltage source Vref can be adjusted according to practical applications. For example, suitable capacitance values and voltage values can be preset for different transistors.

The above embodiments provide an X-ray sensing panel, wherein a compensation circuit is coupled to the non-inverting input end of the integrator circuit to provide a compensation signal to the integrator circuit. In this way, a compensation signal can be provided during the rising period or falling period of the scanning signal to offset the error caused by the potential change period of the scanning signal, thereby increasing the accuracy of the X-ray sensing panel and avoiding the influence on the interpretation of the sensing result. In addition, the above-mentioned compensation circuit of the present invention has a simple structure and can perform compensation without increasing the complexity of the circuit.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection should be defined by the claims.

Claims (10)

1. An X-ray sensing panel, comprising: Multiple data lines; Multiple scan lines; a plurality of pixel elements arranged in a matrix array, the plurality of pixel elements are coupled to the corresponding data lines and the scanning lines for generating a sensing signal; a plurality of integrator circuits, the plurality of integrator circuits include an operational amplifier, an inverting input terminal of the operational amplifier is coupled to the corresponding data line for receiving the sensing signal through the data line; A plurality of compensation circuits, the plurality of compensation circuits are coupled to a corresponding non-inverting input terminal of the operational amplifier for providing a compensation signal to the corresponding integrator circuit. 2. The X-ray sensing panel according to claim 1, wherein the compensation circuit comprises: a capacitor coupled to the non-inverting input terminal of the operational amplifier; an AC voltage source coupled to the capacitor; and A switch is coupled between the non-inverting input terminal of the operational amplifier and the AC voltage source. 3. The X-ray sensing panel according to claim 2, wherein the pixel element comprises: a photodiode for generating the sensing signal according to an optical signal; and A transistor has a first terminal, a second terminal and a control terminal, the first terminal is coupled to the photodiode, the second terminal is coupled to the integrator circuit, and the control terminal is used to receive a scan signal . 4. The X-ray sensing panel according to claim 3, characterized in that, during a rising period when the scanning signal changes from a low potential to a high potential, the switch is turned on, and the compensation signal is a negative voltage signal . 5. The X-ray sensing panel according to claim 3, characterized in that, during a falling period when the scanning signal changes from a high potential to a low potential, the switch is turned on, and the compensation signal is a forward voltage Signal. 6. The X-ray sensing panel as claimed in claim 3, wherein the switch is closed during a period other than a rising period and a falling period when the potential of the scanning signal changes, and the compensation signal is a direct current bias signal. 7. The X-ray sensing panel as claimed in claim 3, wherein a voltage value of the AC voltage source is determined by at least one parasitic capacitance of the transistor. 8. The X-ray sensing panel as claimed in claim 3, wherein a capacitance value of the capacitor is determined by at least one parasitic capacitance of the transistor. 9. The X-ray sensing panel as claimed in claim 1, wherein the X-ray sensing panel further comprises: A scintillator is used to convert an X-ray signal into a visible light signal. 10. The X-ray sensing panel according to claim 1, wherein the X-ray sensing panel further comprises: A scan driving circuit is used for providing a scan signal to the plurality of pixel elements through the plurality of scan lines.