CN108172152B - Current detection device and detection method of display panel - Google Patents

Fig. 2 is a block diagram illustrating an exemplary display

20 according to the present disclosure.

As shown in fig. 2, an exemplary display

20 according to the present disclosure includes a multi-tap

201, a

203, a

205, a

207, and a

209.

As can be seen from the figure, the arrows indicate the flow directions of the control signal and the sampling signal, and the

207 controls the multi-tap

201, the

203, and the

209 according to the received value from the

205.

The

207 is a processor capable of performing data processing, and may be various types of processor chips such as a single chip processor, a Digital Signal Processor (DSP), a Complex Programmable Logic Device (CPLD), and the like. It will be appreciated that since the processor is a digital processor, for processor chips without an integrated AD converter, the

207 should also have interface circuitry and AD converter circuitry accordingly. It is only necessary to make simple extensions according to the functions and communication protocols of the processor.

For each display

20, a voltage fitting function of the display

20 is obtained before the display

20 is connected to a display panel to be inspected. So that the voltage compensation is performed in real time according to the variation of the input driving signal during the test. The resulting fit function is stored in the memory of the

207 to be called at test time.

As shown in fig. 2, the voltage drop of the multi-step

201 is used as the input signal of the display

20. The multi-gear

201 includes a sampling resistor having a plurality of gears, such as a microampere (μ a) gear sampling resistor, a milliamp (mA) gear sampling resistor, an ampere (a) gear sampling resistor, and the like. The gear and the resistance value can be freely adjusted in real time according to the control signal of the

207.

Similar to the multi-gear

201, the

203 is a compensation resistor connected to an input end of the

205 opposite to the multi-gear current collection resistor, and is configured to compensate for a sampling resistor in the multi-gear

201, and therefore, the

203 includes compensation resistors of multiple gears. And the gear corresponds to the gear of the sampling resistor in the multi-gear current collecting

201, and the resistance value of the

203 is equal to the resistance value of the sampling resistor according to the set resistance value of the sampling resistor during testing. Preferably, the compensation resistor should be connected to the low input impedance side of the sampling resistor.

In the present embodiment, as shown, the

209 performs voltage compensation to the

205 according to the control of the

207, and it should be understood that the

209 is connected to the reference input terminal of the

205. For the

205, detection errors can be reduced by real-time compensation when the common mode signal varies. In addition, the

205 of the present disclosure is a high common mode differential operational amplifier to satisfy the test of high driving signal. It should be understood by those skilled in the art that due to the structural characteristics of the operational amplifier, the forward input terminal and the backward input terminal have the "virtual short and virtual break" feature, so that when the compensation voltage is input at the reference voltage input terminal, the range of the input window can be adjusted, and for the input voltage signal exceeding the AD conversion range, the sampling window is changed through the compensation effect, so that the measurement is more flexible.

FIG. 3 is a flow chart diagram 30 illustrating a method of testing an exemplary display

20 according to the present disclosure.

As shown in fig. 3, first, in step S301, in a case where the display panel to be tested is not connected to the display

20 of the present disclosure before detection (generally before shipment, and in a case where the stored data is destroyed in a few cases), a fitting potential is input to the input terminal of the display

20, a fitting function of the compensation voltage is obtained from the output of the differential amplification module at the fitting potential, and the obtained fitting function is stored in the

207.

Since the display

20 of the present disclosure is used to test various types of display panels, in order to simplify the test steps, a fitting function suitable for driving signals of different types of display panels should be fitted. Preferably, fitting voltages of +30V, 0V, and-30V may be input, respectively, and the resulting fitting voltages are stored in the

207.

In step S303, the display panel to be tested is connected in series with the display

20, a driving signal is output to the display panel to be tested through the

207, the stored fitting function is read according to the value of the input driving signal, the compensation voltage corresponding to the driving signal is obtained, and the compensation voltage of the

209 is set.

In step S305, according to the value output by the difference amplifying

205, the

207 adjusts the shift of the sampling resistor in the multi-shift

201, and adjusts the shift of the compensation resistor in the

203 following the shift of the sampling resistor.

Specifically, because the resistance in the multi-step

201 is divided into multiple steps, each step corresponds to a different measuring range, when the equivalent range is selected to be too large, for example, when a mA step is selected, if the output value is close to zero, the output value can be adjusted to the μ a step. Conversely, when the range is selected too small, for example, when the μ a range is selected, the output value may be adjusted to the mA range if the output value approaches the full range. Correspondingly, the

203 selects the same value following the change of the gears and the numerical values of the multi-gear

201 to suppress the influence of the common-mode signal change on the detection.

In step S307, the

207 performs calculation according to the measured value output by the

205, obtains a current value flowing in the display panel through ohm' S law, and determines whether the display panel to be detected is normal according to the detected current value.

1. A current detection device of a display panel, comprising: a multi-gear current acquisition resistor, a resistance compensation module, a differential amplification module, a voltage compensation module and a sampling control module,

before delivery, the sampling control module fits a fitting function of the compensation voltage through a fitting potential applied in the current detection device, and stores the fitting function in the sampling control module for repeated use in subsequent tests;

when in testing, the sampling control module applies different driving signals according to different display panels or different tests of the display panels, and the sampling control module controls the voltage compensation module to perform voltage compensation based on the fitting function and controls the resistance compensation module to perform resistance compensation;

and the sampling control module calculates the current flowing through the display panel to be detected according to the compensated output of the differential amplification module, and judges whether the display panel to be detected is normal.

2. The current detection device of claim 1, wherein the differential amplifier module is a high common mode differential operational amplifier for detecting a large voltage signal or a small voltage signal.

3. The current detection device of the display panel according to claim 2, wherein a voltage across the multi-tap current collection resistor is used as an input signal of the differential amplification module, and the resistance compensation module is connected to a low input impedance side of the multi-tap current collection resistor.

4. The current detection device of the display panel according to claim 1, wherein the multi-tap current collection resistor includes a sampling resistor of a plurality of taps, and the resistance compensation module includes a compensation resistor of a plurality of taps corresponding to the multi-tap current collection resistor,

the sampling control module controls the setting of the multi-gear current acquisition resistor and the gear of the resistor compensation module according to the value output by the differential amplification module.

5. The current detection device of a display panel according to claim 3 or 4,

and the voltage compensation module is connected with the input end serving as a reference input end in the differential amplification module.

6. A current detection method of a display panel for use in the current detection device according to any one of claims 1 to 5, characterized by comprising the steps of:

under the condition of not connecting the display panel to be tested, inputting a plurality of fitting potentials to obtain a fitting function of the compensation voltage, and storing the fitting function in the sampling control module;

accessing the display panel to be tested, applying a driving signal to the display panel to be tested, and obtaining a compensation voltage through the fitting function according to the voltage value of the driving signal;

based on the value output by the differential amplification module, adjusting the gears of the multi-gear current acquisition resistor and adjusting the gears of the corresponding compensation resistor; and

and calculating the current in the display panel to be tested according to the measured value output by the differential amplification module, and judging whether the display panel to be tested is normal or not.

7. The method for detecting current of a display panel according to claim 6, wherein the inputting a plurality of fitting potentials and deriving a fitting function of the compensation voltage comprises:

and fitting in the intervals of the reference potentials respectively to obtain a plurality of fitting functions, wherein the obtained fitting functions are piecewise functions.

8. The current detection method of the display panel according to claim 6, wherein the adjusting the shift of the multi-shift current collection resistor based on the value output by the differential amplification module comprises:

when the current value measured by the set gear of the sampling resistor is close to the upper limit of the measuring range, the sampling control module lowers the gear of the sampling resistor of the multi-gear current acquisition resistor, correspondingly adjusts the gear of a compensation resistor in the resistor compensation module, and

when the current value measured by the set gear of the sampling resistor is close to zero, the sampling control module adjusts the gear of the sampling resistor of the multi-gear current acquisition resistor to be high, and correspondingly adjusts the gear of the compensation resistor in the resistor compensation module.

9. The current detection method of a display panel according to claim 8, wherein a value of the compensation resistor is set to be equal to a resistance value of the sampling resistor in accordance with a corresponding resistance value in a shift position of the set sampling resistor.