Open and short circuit testing device for TFT (thin film transistor) backplane

Abstract

The utility model discloses an open-short circuit test device for a TFT (thin film transistor) back plate, and the device comprises a selection unit which responds to the control of a control unit, selects the output end of one of a current feedback unit and a voltage feedback unit to be connected to a clamping unit, and selects the output end of the other one to be connected to a driving unit; the driving unit outputs a driving signal based on a feedback signal of the feedback unit accessed by the driving unit and a preset output signal set by the control unit so as to drive the to-be-tested product; the clamping unit is used for controlling the conduction state of the driving unit based on a feedback signal of the feedback unit accessed by the clamping unit and the clamping value set by the control unit; and the control unit is used for judging whether the open circuit and the short circuit occur at the position to be detected according to the output voltage acquired by the voltage feedback unit and the output current acquired by the current feedback unit. According to the open and short circuit testing device, the feedback signals of the feedback current and voltage are used for clamping and driving, and the testing precision is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of display technology, and in particular to an open-short circuit testing device for a TFT backplane. Background Art

[0002] With the development of display technology, the integration level of thin film transistor (TFT) backplane circuits is getting higher and higher. The open and short (OS) test requirements of TFT backplanes have changed from the original OS determination to the need to measure the precise resistance between each circuit and each welding point (pad). The test requirements are becoming more and more precise. The existing measurement schemes all use voltage measurement. With the development of TFT backplanes, their driving voltage is getting lower and lower, and the test voltage value is also getting lower and lower. The existing test devices are basically unable to accurately measure the resistance between each circuit and each pad. However, increasing the test voltage value may mistakenly drive the gate of the transistor on the TFT backplane, resulting in incorrect test results.

[0003] Therefore, it is necessary to provide an open-short circuit testing device capable of accurately measuring the resistance value of each circuit on the TFT backplane. Summary of the invention

[0004] In order to solve at least one of the above problems, the present disclosure provides an open-short circuit test device for a TFT backplane, comprising: a control unit, a driving unit, a current feedback unit, a voltage feedback unit, a selection unit and a clamping unit, wherein:

[0005] The selection unit is configured to select an output terminal of one of the current feedback unit and the voltage feedback unit to be connected to the clamp unit and select an output terminal of the other one to be connected to the driving unit in response to control of the control unit.

[0006] The driving unit outputs a driving signal to drive the product to be tested based on the feedback signal of the feedback unit connected thereto and the preset output signal set by the control unit.

[0007] The clamping unit controls the conduction state of the driving unit based on the feedback signal of the feedback unit connected thereto and the clamping value set by the control unit.

[0008] The control unit is configured to determine whether an open or short circuit occurs in the product to be tested according to the output voltage of the open or short circuit test device collected by the voltage feedback unit and the output current of the open or short circuit test device collected by the current feedback unit.

[0009] Optionally, the selection unit includes a first switch module and a second switch module.

[0010] When the voltage feedback unit is electrically connected to the driving unit through the first switch module and the current feedback unit is electrically connected to the clamping unit through the second switch module, the control unit sets a preset output voltage signal and provides it to the driving unit and sets a current clamping value and provides it to the clamping unit.

[0011] Optionally, the selection unit includes a first switch module and a second switch module.

[0012] When the voltage feedback unit is electrically connected to the clamping unit through the first switch module and the current feedback unit is electrically connected to the driving unit through the second switch module, the control unit sets a preset output current signal and provides it to the driving unit and sets a voltage clamping value and provides it to the clamping unit.

[0013] Optionally, the open-short circuit test device further comprises: a first digital-to-analog converter,

[0014] The first digital-to-analog converter is electrically connected between the control unit and the clamping unit, and is used for converting the digital signal output by the clamping unit into an analog signal and inputting the analog signal into the clamping unit as a clamping value.

[0015] Optionally, the open-short circuit test device further comprises: a second digital-to-analog converter,

[0016] The second digital-to-analog converter is electrically connected between the control unit and the driving unit, and is used for converting the digital signal output by the control unit into an analog signal and inputting the analog signal into the driving unit as a preset output signal.

[0017] Optionally, a sampling resistor is further included, one end of the sampling resistor is electrically connected to the output end of the driving unit, and the other end serves as the output end of the open-short circuit testing device.

[0018] Optionally,

[0019] The first input end of the current feedback unit is electrically connected to the output end of the driving unit, and the second input end is electrically connected to the output end of the open-short circuit test device, and is used to collect the output current of the open-short circuit test device.

[0020] The first input terminal of the voltage feedback unit is electrically connected to the output terminal of the open-short circuit test device, and the second input terminal is grounded, and is used to collect the output voltage of the open-short circuit test device.

[0021] Optionally, the control unit calculates the resistance value of the product to be tested according to the output voltage and the output current to determine whether an open circuit or a short circuit occurs therein.

[0022] Optionally, the open-short circuit test device further comprises: a first analog-to-digital converter,

[0023] The first analog-to-digital converter is electrically connected between the current feedback unit and the control unit, and is used for converting the collected output current value into a digital signal and sending it to the control unit.

[0024] Optionally, the open-short circuit test device further comprises: a second analog-to-digital converter,

[0025] The second analog-to-digital converter is electrically connected between the voltage feedback unit and the control unit, and is used for converting the collected output voltage value into a digital signal and sending it to the control unit.

[0026] The beneficial effects of the present disclosure are as follows:

[0027] In view of the existing problems, the present invention develops an open-short circuit test device for a TFT backplane, which provides a current feedback unit and a voltage feedback unit for respectively measuring the voltage and current at the output end, and selectively connects the current feedback unit and the voltage feedback unit as feedback loops to the input end of a driving unit and the input end of a clamping unit, thereby accurately and stably controlling the signal output to the product to be tested, and being able to obtain an accurate impedance value for open-circuit and short-circuit state judgment; in addition, once the output end voltage or current is found to be abnormal, the driving signal can be clamped in time to protect the position to be tested of the TFT backplane from high voltage or high current shocks, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A schematic block diagram of an open-short circuit testing device according to an embodiment of the present disclosure is shown;

[0030] Figure 2 A schematic block diagram showing an open-short circuit testing device according to another embodiment of the present disclosure is shown;

[0031] Figure 3 A schematic circuit diagram of an open-short circuit testing device according to an embodiment of the present disclosure is shown;

[0032] Figure 4 A test process block diagram of an open-short circuit test device according to an embodiment of the present disclosure is shown; and

[0033] Figure 5 A test process block diagram of an open-short circuit test device according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0034] In order to more clearly illustrate the present disclosure, the present disclosure is further described below in conjunction with preferred embodiments and drawings. Similar components in the drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the content described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present disclosure.

[0035] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, similar words such as "one", "one" or "the" do not indicate a quantitative limit, but indicate that there is at least one. "Include" or "comprises" and other similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and other similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0036] In order to solve at least one of the above problems, refer to Figure 1 As shown, the embodiment of the present disclosure provides an open-short circuit test device for a TFT backplane, comprising: a control unit 11, a driving unit 12, a current feedback unit 13, a voltage feedback unit 14, a selection unit 15 and a clamping unit 16, wherein:

[0037] The selection unit 15 is configured to select the output end of one of the current feedback unit 13 and the voltage feedback unit 14 to be connected to the clamp unit 16 and select the output end of the other one to be connected to the driving unit 12 in response to the control of the control unit 11.

[0038] The driving unit 12 drives the product to be tested based on the feedback signal of the feedback unit connected thereto and the preset output signal set by the control unit 11.

[0039] The clamping unit 16 controls the conduction state of the driving unit 12 based on the feedback signal of the feedback unit connected thereto and the clamping value set by the control unit 11.

[0040] The control unit 11 is configured to determine whether an open or short circuit occurs at the position to be tested according to the output voltage of the open or short circuit test device collected by the voltage feedback unit 14 and the output current of the open or short circuit test device collected by the current feedback unit 13 .

[0041] In this embodiment, a current feedback unit and a voltage feedback unit are provided for respectively measuring the voltage and current at the output end, and the current feedback unit and the voltage feedback unit are selectively connected to the input end of the driving unit and the input end of the clamping unit as a feedback loop, so as to accurately and stably control the signal output to the product to be tested, and obtain an accurate impedance value for open circuit and short circuit state judgment; in addition, once the output voltage or current is found to be abnormal, the driving signal can be clamped in time to protect the position to be tested of the TFT backplane from high voltage or high current shock.

[0042] In order to further understand the structure and function of the present disclosure, a detailed description is given below in conjunction with embodiments.

[0043] Reference Figure 2 As shown, the figure provides an exemplary open-short circuit testing device 1 for a TFT back panel.

[0044] For clarity, in Figure 2 The flow of key signals is shown in FIG. 1 and the control signal path from the control unit 11 to the selection unit 15 is omitted.

[0045] like Figure 2 As shown, the open-short circuit testing device 1 includes a control unit 11 , a driving unit 12 , a current feedback unit 13 , a voltage feedback unit 14 , a selection unit 15 and a clamping unit 16 .

[0046] Among them, the selection unit 15 is electrically connected to the control unit 11, the driving unit 12, the current feedback unit 13, the voltage feedback unit 14, and the clamping unit 16 respectively, and is configured to select the output end of one of the current feedback unit 13 and the voltage feedback unit 14 to be connected to the clamping unit 16 in response to the control signal output by the control unit 11, and select the output end of the other of the current feedback unit 13 and the voltage feedback unit 14 to be connected to the driving unit 12.

[0047] Optionally, the selection unit 15 includes a first switch module S1 and a second switch module S2. When the open-short circuit test device 1 is in the voltage test mode, the first switch module S1 electrically connects the voltage feedback unit 14 to the first input terminal of the driving unit 12 in response to the control of the control unit 11, and the second switch module S2 electrically connects the current feedback unit 13 to the first input terminal of the clamping unit 16 in response to the control of the control unit 11, or

[0048] When the open-short circuit test device 1 is in the current test mode, the first switch module S1 electrically connects the current feedback unit 13 with the first input end of the driving unit 12 in response to the control of the control unit 11, and the second switch module S2 electrically connects the voltage feedback unit 14 with the first input end of the clamping unit 16 in response to the control of the control unit 11.

[0049] When the voltage feedback unit 14 is electrically connected to the drive unit 12 through the first switch module S1 and the current feedback unit 13 is electrically connected to the clamp unit 16 through the second switch module S2, the control unit 11 sets a preset output voltage signal and provides it to the drive unit 12 and sets a current clamp value and provides it to the clamp unit 16. When the voltage feedback unit 14 is electrically connected to the clamp unit 16 through the first switch module S1 and the current feedback unit 13 is electrically connected to the drive unit 12 through the second switch module S2, the control unit 11 sets a preset output current signal and provides it to the drive unit 12 and sets a voltage clamp value and provides it to the clamp unit 16.

[0050] Specific to Figure 2 In the example in the figure, the path connection state in the current measurement mode is shown, and the first switch module S1 in the selection unit 15 selects to connect the current feedback unit 13 to the drive unit 12, and the voltage feedback unit 14 to the clamping unit 16, that is, the feedback signal output by the current feedback unit 13 is input to the drive unit 12 as the current feedback signal of the drive unit, and the feedback signal output by the voltage feedback unit 14 is input to the clamping circuit as the clamping basis.

[0051] A person skilled in the art can understand from the accompanying drawings that, in response to the control signal output by the control unit 11, when the first switch module S1 and the second switch module S2 are converted from the current first closed state to the second closed state, the selection unit 15 will select the current feedback unit 13 to be connected to the clamping unit 16 and the voltage feedback unit 14 to be connected to the drive unit 12, then the feedback signal of the current feedback unit 13 will be used as the clamping basis of the clamping unit 16, and the feedback signal of the voltage feedback unit 14 will be used as the voltage feedback signal of the drive unit 12.

[0052] The present application does not intend to limit the specific structure of the selection unit 15 , as long as it is an equivalent switch structure that can select between two circuit connection states based on the control of the driving unit 11 .

[0053] Exemplarily, the switch unit may be a relay or a contactor. Specifically, in the voltage test mode, the first switch module S1 is in a normally open state and the second switch module S2 is in a normally open state, and in the current test mode, the first switch module S1 is in a normally closed state and the second switch module S2 is in a normally closed state.

[0054] Continue to refer to Figure 2 As shown, the driving unit 12 is electrically connected to the control unit 11, the selection unit 15, the current feedback unit 13, the voltage feedback unit 14, and the clamping unit 16, and generates a driving signal for testing based on the feedback signal of the selected feedback unit and the preset output signal from the control unit 11.

[0055] It can be seen that in the embodiment of the present disclosure, the driving unit 12, as a signal generating unit of the driving signal for testing, is not only controlled by the preset output signal of the control unit 11, but also controlled by the driving signal for testing collected by one of the selected current feedback unit 13 and the voltage feedback unit 14. In other words, the driving signal collected by the current feedback unit 13 or the voltage feedback unit 14 is used to generate a feedback loop and further form a loop modulation gain for automatic dynamic modulation of the output of the driving unit 12, so as to ensure that the driving signal generated by the driving unit 12 can be accurately modulated to an amplitude that meets the requirements of the position to be tested, so as to ensure accurate measurement of the resistance between each line and each Pad point to be tested on the TFT backplane, without driving the gate (Gate) on the TFT backplane by mistake, thereby avoiding errors in the test results. In addition, by forming a feedback gain loop using the output end driving signal of the driving unit 12, it is possible to ensure that the output end signal amplitude is stable, and at the same time form a circuit protection for the TFT backplane to be tested, thereby avoiding burning of the TFT backplane during the test phase.

[0056] Continue to refer to Figure 2 As shown, the clamping unit 16 is electrically connected to the control unit 11, the driving unit 12, and the selecting unit 15, and is configured to clamp the driving signal based on the selected feedback signal and the clamping value from the control unit 11. Figure 2 As shown, if the selection unit 15 chooses to connect the current feedback unit 13 to the driving unit 12, the feedback signal of the voltage feedback unit 14 will be used as the clamping basis, and the control unit 11 will clamp the value to the clamping unit 16, and together with the voltage signal measured by the voltage feedback unit 14, limit the driving signal amplitude at the output end of the driving unit 12 to avoid the instantaneous large voltage signal at the output end from damaging the TFT backplane to be tested.

[0057] Continue to refer to Figure 2 As shown, the control unit 11 is further configured to receive a current feedback signal from the current feedback unit 13 and a voltage feedback signal from the voltage feedback unit 14 to obtain an open-circuit resistance value. Figure 2 As shown, the process of the control unit 11 receiving the current feedback signal and the voltage feedback signal is not controlled by the selection unit 15. Two feedback signals are received during each measurement process, so that the accurate resistance value of the current measured circuit and Pad point of the TFT backplane to be measured can be calculated by Ohm's law to determine the short circuit and open circuit states, rather than directly obtaining the open circuit and short circuit results.

[0058] This setting is beneficial for testing TFT backplane structures with increasing integration. Since the distance between lines is getting smaller and the pad point size is getting smaller, for a specific backplane structure, it is not a simple matter of using infinite voltage or 0 volts to judge open circuit and short circuit. A resistance value of several ohms or tens of ohms may be judged as a short circuit, or a resistance value greater than hundreds or thousands of ohms may be judged as an open circuit. The test device disclosed in the present invention can obtain more accurate open and short circuit measurement results to meet the testing requirements of more complex or advanced backplanes.

[0059] Optionally, the control unit 11 may be one of a microcontroller unit (MCU), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA). Because the control unit 11 in the embodiment of the present disclosure only needs to have a simple voltage and current signal output function and perform a simple division operation based on the received feedback signal, the control unit 11 may select a CPLD based on considerations such as cost and test time.

[0060] Optionally, refer to Figure 2 As shown, the open-short circuit test device 1 also includes a sampling resistor R, one end of which is electrically connected to the output end of the drive unit 12, and the other end serves as the output end of the open-short circuit test device 1, for collecting the output current of the drive unit 12, that is, the current signal output by the open-short circuit test device 1.

[0061] Optionally, refer to Figure 2 As shown, the open-short circuit test device 1 of the embodiment of the present disclosure further includes: a first digital-to-analog conversion unit 17-1, and the first digital-to-analog converter 17-1 is used to convert the clamping value output by the control unit 11 from a digital signal to an analog signal. Exemplarily, the first digital-to-analog converter 17-1 is electrically connected between the control unit 11 and the clamping unit 16, and is used to convert the digital signal output by the control unit 11 into an analog signal and input it into the clamping unit 16 as a clamping value.

[0062] Optionally, refer to Figure 2 As shown, the open-short circuit test device 1 of the embodiment of the present disclosure further includes: a second digital-to-analog converter 17-2, which is used to convert the preset signal set by the control unit 11 from a digital signal to an analog signal. Exemplarily, the second digital-to-analog converter 17-2 is electrically connected between the control unit 11 and the drive unit 12, and is used to convert the digital signal output by the control unit 11 into an analog signal and input it to the drive unit 12 as a preset output signal.

[0063] Optionally, refer to Figure 2 As shown, in addition to the digital-to-analog converter, the open-short circuit test device 1 of the embodiment of the present disclosure also includes: a first analog-to-digital converter 18-1, and the first analog-to-digital converter 18-1 is used to convert the output current of the open-short circuit test device 1 collected by the current feedback unit 13 from an analog signal to a digital signal.

[0064] Optionally, refer to Figure 2 As shown, the open-short circuit test device 1 of the embodiment of the present disclosure further includes: a second analog-to-digital converter 18-2, which is used to convert the output voltage of the open-short circuit test device 1 collected by the voltage feedback unit 14 from an analog signal to a digital signal.

[0065] It should be noted that, due to the existence of the selection unit 15, there is more than one specific connection position of the first analog-to-digital converter 18-1 and the second analog-to-digital converter 18-2. That is, based on the configuration of the first switch module S1 and the second switch module S2, the first analog-to-digital converter 18-1 can be electrically connected between the first switch module S1 and the control unit 11 or between the current feedback unit 13 and the control unit 11; the second analog-to-digital converter 18-2 can be electrically connected between the second switch module S2 and the control unit 11 or between the voltage feedback unit 14 and the control unit 11, as long as the above analog-to-digital conversion function can be realized.

[0066] Figure 3 Show satisfaction Figure 2 A schematic circuit diagram of the embodiment is shown, in which the control unit 11 is omitted.

[0067] It should be noted that Figure 3 The structure is only exemplary to help understand the present disclosure, and is not intended to limit the circuit structure of the open-short circuit test device 1 in the embodiment of the present disclosure. Those skilled in the art can understand that other specific circuit structure details can also realize the functions of each unit in the present disclosure, such as the number of stages of the amplifier circuit, the loop composition of the amplifier circuit, etc., which can be simply set according to the specific application scenario and measurement needs.

[0068] Reference Figure 3As shown, in this example, the sampling resistor R is specifically: sampling resistors RS1, RS2 and RS3, one end of the sampling resistors RS1, RS2 and RS3 is electrically connected to the output end of the driving unit 12, and the other end is used as the output end of the open-short circuit test device 1, the first input end of the current feedback unit 13 is electrically connected to the above one end of the sampling resistors RS1, RS2 and RS3, the second input end is electrically connected to the above other end of the sampling resistors RS1, RS2 and RS3, and the input end of the voltage feedback unit 14 is electrically connected to the above other end of the sampling resistors RS1, RS2 and RS3. The output current of the driving unit 12 collected by the current feedback unit 13 is input to the current feedback unit 13 in the form of a voltage drop of the sampling resistors RS1, RS2 and RS3.

[0069] Specifically, in this example, the driving unit 12 includes a three-stage amplification function to ensure sufficient driving capability, but is not limited thereto; the sampling resistor RS1 is electrically connected to the output end of the open-short circuit test device 1 through a switch S3, the sampling resistor RS2 is electrically connected to the output end of the open-short circuit test device 1 through a switch S4, and the sampling resistor RS3 is electrically connected to the output end of the open-short circuit test device 1 through a switch S5. Each sampling resistor can be set with a different resistance value and connected to different circuits according to the display panel to be tested, thereby providing more accurate measurement results.

[0070] Reference Figure 3 As shown, the current feedback unit 13 collects the current output by the open-short circuit test device 1, that is, collects the current of the test loop, and the voltage feedback unit 14 collects the output voltage of the open-short circuit test device 1, that is, collects the voltage of the tested circuit DUT (i.e., the tested position) of the tested display panel.

[0071] Specifically in this example, the first analog-to-digital converter 18-1 is electrically connected between the current feedback unit 13 and the control unit 11, and is used to convert the output current value collected by it into a digital signal and send it to the control unit, and the second analog-to-digital converter 18-2 is electrically connected between the voltage feedback unit 14 and the control unit 11, and is used to convert the output voltage value collected by it into a digital signal and send it to the control unit 11. In this example, the first analog-to-digital converter 18-1 is the analog-to-digital conversion circuit ADC1, and the second analog-to-digital converter 18-2 is the analog-to-digital conversion circuit ADC2.

[0072] The control unit 11 receives the current feedback signal I and the voltage feedback signal V, and obtains a specific resistance value according to Ohm's law R=V / I.

[0073] Because the current feedback unit 13 and the voltage feedback unit 14 simultaneously serve as feedback loops of the driving unit 12 for adjusting the amplitude of the driving signal in real time according to the measured end, the two feedback loops have corresponding amplification factors.

[0074] More preferably, in order to offset the amplification factor when performing ohmic operation, the current feedback unit 13 is an amplifier circuit with a first amplification factor, and the voltage feedback unit 14 is an amplifier circuit with a second amplification factor, wherein the first amplification factor is equal to the second amplification factor.

[0075] Considering that the higher the sampling current and the input impedance of the sampling current are, the higher the sampling accuracy is, therefore, optionally, referring to Figure 3 As shown, the detection input terminal of the current feedback unit 13 and the detection input terminal of the voltage feedback unit 14 both include a follower circuit.

[0076] Through this configuration, the advantage of the operational amplifier circuit being virtual-off can be utilized to provide extremely high input impedance, thereby ensuring sampling accuracy. Preferably, the follower circuit can use an operational amplifier with high input impedance.

[0077] Optionally, in order to eliminate the influence of the impedance on the test line on the accuracy of the test result, the voltage feedback unit 14 should be connected to the positive test terminal DUT_S+ close to the sampling test circuit DUT, and the other end of the input stage of the voltage feedback unit 14 is connected to the sampling ground DUT_S-.

[0078] Specifically for this example, the clamping unit 16 has the ability to clamp positive and negative signals. That is, the first digital-to-analog converter 17-1 includes two digital-to-analog conversion circuits DAC2 and DAC3, that is, the input end of the first digital-to-analog converter 17-1 includes two input pins, and the output end also includes two output pins. When applied, positive and negative clamping values ​​are input at the same time, and a clamping signal is output according to the specific value of the feedback signal fed back to the clamping unit 16. The clamping signal will be connected as the comparison input end of the middle-stage operational amplifier of the driving unit 12, thereby affecting the final output amplitude of the driving unit 12, so as to play a clamping role, thereby protecting the display panel to be tested.

[0079] Alternatively, considering that not all analog-to-digital conversion units have the negative signal conversion function, when the open-short circuit test device 1 uses an analog-to-digital conversion unit that does not have the negative signal conversion function, it may also include a positive-negative signal conversion unit (not shown).

[0080] Specific to Figure 3 As an example, the open-short circuit test device 1 may include a first positive-negative signal conversion unit and a second positive-negative signal conversion unit, the first positive-negative signal conversion unit is arranged between the current feedback unit 13 and the first analog-to-digital conversion circuit ADC1 to convert the negative current feedback signal into a positive signal input into the first analog-to-digital conversion circuit ADC1, and the second positive-negative signal conversion unit is arranged between the voltage feedback unit 14 and the second analog-to-digital conversion circuit ADC2 to convert the negative voltage feedback signal into a positive signal input into the second analog-to-digital conversion circuit ADC2.

[0081] The open-circuit and short-circuit test device 1 of the above embodiment can meet the requirements of precise open-circuit and short-circuit tests on the current, voltage and anti-aging functions of the TFT backplane.

[0082] Combination Figure 3 and Figure 4 As shown, when voltage measurement or current measurement is performed, an open-short circuit test device 1 is used, and one end of the circuit end DUT to be tested is connected to the open-short circuit test device 1, and the other end is grounded.

[0083] When measuring voltage, if the first switch module S1 and the second switch module S2 are relays, such as electromagnetic relay switches, the first switch module S1 can be switched to a normally open contact, and the second switch module S2 is switched to a normally open contact, then the current feedback unit 13 is connected to the clamping unit 16, the voltage feedback unit 14 is connected to the drive unit 12, and the digital-to-analog conversion circuits DAC2 and DAC3 respectively input the clamping value of the positive clamp and the clamping value of the negative clamp, and the clamping value is the current clamping value, such as +80mA and -80mA. The current feedback unit 13 reads the current measurement value I from the sampling resistor and inputs it into the first analog-to-digital conversion circuit ADC1, and the voltage feedback unit 14 reads the voltage measurement value V from the circuit under test DUT and inputs it into the second analog-to-digital conversion circuit ADC2.

[0084] The control unit 11 calculates the resistance R=V / I of the circuit under test DUT by division operation, thereby obtaining an accurate resistance value, so as to determine whether the resistance value represents an open circuit or a short circuit state according to the specific TFT backplane.

[0085] When measuring current, if the first switch module S1 and the second switch module S2 are still relays, such as electromagnetic relay switches, the first switch module S1 can be switched to a normally closed contact, and the second switch module S2 is switched to a normally closed contact, then the voltage feedback unit 14 is connected to the clamping unit 16, the current feedback unit 13 is connected to the drive unit 12, and the digital-to-analog conversion circuits DAC2 and DAC3 respectively input the clamping value of the positive clamp and the clamping value of the negative clamp, and the clamping value is a voltage clamping value, such as +10V and -10V. The current feedback unit 13 reads the current measurement value I from the sampling resistor and inputs it into the first analog-to-digital conversion circuit ADC1, and the voltage feedback unit 14 reads the voltage measurement value V from the circuit under test DUT and inputs it into the second analog-to-digital conversion circuit ADC2.

[0086] The control unit 11 calculates the resistance R=V / I of the circuit under test DUT by division operation, thereby obtaining an accurate resistance value, so as to determine whether the resistance value represents an open circuit or a short circuit state according to the specific TFT backplane.

[0087] When performing aging tests, refer to Figure 5As shown, the test can be completed by cooperating with two open-short circuit test devices 1. The two open-short circuit test devices 1 are respectively connected to the two ends of the circuit DUT to be tested, and according to the selected current aging or voltage aging, if the current is aging, the two open-short circuit test devices 1 are connected in a current measurement mode, and if the current is aging, the two open-short circuit test devices 1 are connected in a voltage measurement mode, which can form a maximum of 20V, 80mA drive signal at both ends of the DUT, and can complete the two functions of voltage aging and current aging.

[0088] In actual application, the output end of the open-short circuit test device 1 can also be electrically connected to the test probe in a one-to-one correspondence. When using one open-short circuit test device 1 for testing, the probe can be electrically connected to one end of the position to be tested on the TFT backplane, and the other end of the position to be tested is grounded, so as to perform a current measurement method or a voltage measurement method; when using two open-short circuit test devices 1 for testing, one of the corresponding probes can be electrically connected to one end of the position to be tested on the TFT backplane, and the other corresponding probe can be electrically connected to the other end of the position to be tested, so as to complete the aging method measurement through one system.

[0089] In view of the existing problems, the present invention develops an open-short circuit test device for a TFT backplane, which provides a current feedback unit and a voltage feedback unit for respectively measuring the voltage and current at the output end, and selectively connects the current feedback unit and the voltage feedback unit as feedback loops to the input end of a driving unit and the input end of a clamping unit, thereby accurately and stably controlling the signal output to the product to be tested, and being able to obtain an accurate impedance value for open-circuit and short-circuit state judgment; in addition, once the output end voltage or current is found to be abnormal, the driving signal can be clamped in time to protect the position to be tested of the TFT backplane from high voltage or high current shocks, and has broad application prospects.

[0090] Obviously, the above embodiments of the present disclosure are merely examples for clearly illustrating the present disclosure, and are not limitations on the implementation methods of the present disclosure. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present disclosure are still within the protection scope of the present disclosure.

Claims

1. A TFT backplane open and short circuit test device, characterized in that: include: A control unit, a driving unit, a current feedback unit, a voltage feedback unit, a selection unit and a clamping unit, wherein: The selection unit is configured to select an output end of one of the current feedback unit and the voltage feedback unit to be connected to the clamp unit and select an output end of the other one to be connected to the driving unit in response to control of the control unit. The driving unit outputs a driving signal to drive the product to be tested based on the feedback signal of the feedback unit connected thereto and the preset output signal set by the control unit. The clamping unit controls the conduction state of the driving unit based on the feedback signal of the feedback unit connected thereto and the clamping value set by the control unit. The control unit is configured to determine whether an open or short circuit occurs in the product to be tested according to the output voltage of the open or short circuit test device collected by the voltage feedback unit and the output current of the open or short circuit test device collected by the current feedback unit.

2. The open-short circuit test device according to claim 1, characterized in that: The selection unit includes a first switch module and a second switch module. When the voltage feedback unit is electrically connected to the driving unit through the first switch module and the current feedback unit is electrically connected to the clamping unit through the second switch module, the control unit sets a preset output voltage signal and provides it to the driving unit and sets a current clamping value and provides it to the clamping unit.

3. The open-short circuit test device according to claim 1, characterized in that: The selection unit includes a first switch module and a second switch module. When the voltage feedback unit is electrically connected to the clamping unit through the first switch module and the current feedback unit is electrically connected to the driving unit through the second switch module, the control unit sets a preset output current signal and provides it to the driving unit and sets a voltage clamping value and provides it to the clamping unit.

4. The open-short circuit test device according to claim 1, characterized in that: Also includes: The first digital-to-analog converter, The first digital-to-analog converter is electrically connected between the control unit and the clamping unit, and is used for converting the digital signal output by the control unit into an analog signal and inputting the analog signal into the clamping unit as a clamping value.

5. The open-short circuit test device according to claim 1, characterized in that: Also includes: The second digital-to-analog converter, The second digital-to-analog converter is electrically connected between the control unit and the driving unit, and is used for converting the digital signal output by the control unit into an analog signal and inputting the analog signal into the driving unit as a preset output signal.

6. The open-short circuit test device according to claim 1, characterized in that: It also includes a sampling resistor, one end of which is electrically connected to the output end of the driving unit, and the other end of which serves as the output end of the open-short circuit testing device.

7. The open-short circuit test device according to claim 6, characterized in that: The first input end of the current feedback unit is electrically connected to the output end of the driving unit, and the second input end is electrically connected to the output end of the open-short circuit test device, and is used to collect the output current of the open-short circuit test device. The first input terminal of the voltage feedback unit is electrically connected to the output terminal of the open-short circuit test device, and the second input terminal is grounded, and is used to collect the output voltage of the open-short circuit test device.

8. The open-short circuit test device according to claim 7, characterized in that: The control unit calculates the resistance value of the product to be tested according to the output voltage and the output current to determine whether an open circuit or a short circuit occurs therein.

9. The open-short circuit test device according to claim 1, characterized in that: Also includes: The first analog-to-digital converter, The first analog-to-digital converter is electrically connected between the current feedback unit and the control unit, and is used for converting the collected output current value into a digital signal and sending it to the control unit.

10. The open-short circuit test device according to claim 1, characterized in that: Also includes: The second analog-to-digital converter, The second analog-to-digital converter is electrically connected between the voltage feedback unit and the control unit, and is used for converting the collected output voltage value into a digital signal and sending it to the control unit.

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