tft lcd monitor test factory

In the past decade, LCD monitors have replaced CRT screens for all but the most specialist applications. Although liquid crystal displays boast perfect

Masuda T, Ajichi Y, Kubo T, Yamamoto T, Shinomiya T, Nakamura M, Shimizu T, Kasai N, Mouri H, Feng XF, Teragawa M (2009) Ultra thin LED backlight system using tandem light guides for large-size LCD-TV. In: IDW09 Proceedings, pp 1857–1860

Wakabayashi K, Mitobe K, Torigoe T (2004) Laser CVD repair technology for final yield improvement method in mass and large size TFT-LCD production process. In: IDW04 Proceedings, pp 623–624

Honoki H, Nakasu N, Arai T, Yoshimura K, Edamura T (2006) In-line automatic defect inspection and repair method for possible highest yield TFT array production. In: IDW06 Proceedings, pp 849–852

A display panel, a manufacturing method therefor, and a thin film transistor (TFT) test method. The display panel comprises a display region (11) and a peripheral region (12) surrounding the display region. The peripheral region comprises: an electroluminescence layer test region (120), a TFT test region (121), and a plurality of pigtails (122). The electroluminescence layer test region (120) comprises a plurality of TFTs with electroluminescence layers (1201), first test lines (1202) connecting sources of the plurality of TFTs with electroluminescence layers (1201), and switch leads (1203) and second test lines (1204) connecting gates of the plurality of TFTs with electroluminescence layers. The TFT test region comprises a plurality of TFTs (1211). Each pigtail of the plurality of pigtails is used to connect a source and drain metal layer of one TFT in the electroluminescence layer test region and a source and drain metal layer of one TFT in the TFT test region.

To clean the anti-static screen, we recommend using a special screen-cleaning tissue or solution that is suitable for the anti-static coating on LCD panels.

Use a soft and clean microfiber cloth that is lightly dampened with water to clean the monitor. Avoid using detergents of any kind as they can leave a milky film on the monitor.

While moving the monitor, follow the instructions as described in the User Manual on how to hold the monitor. Do not put pressure directly on the LCD screen as it may cause irreparable cracks.

WARNING: Before cleaning the monitor, unplug the monitor power cable from the electrical outlet, and the video cables from the monitor. Read and follow the Safety Instructions before cleaning the monitor.

To run a diagnostic test on the LCD panel of a Dell laptop, see the Dell knowledge base article How to Run the LCD Built-in Self-Test on a Dell Laptop.

If the screen abnormality is not present in the integrated self-test mode, see the Dell knowledge base article How to Troubleshoot Display or Video Issues on a Dell Monitor.

Running a self-test feature check (STFC) or the built-in self-test (BIST) diagnostic on a Dell monitor is always a good practice to isolate LCD or monitor issues.

If the self-test feature check (STFC) or built-in self-test (BIST) diagnostic test passed, this indicates that the Dell monitor is functioning normally. To troubleshoot the display or video issue, see the Dell knowledge base article How to Troubleshoot Display or Video Issues on a Dell Monitor.

The instructions to reset the Dell monitor to factory default settings (also called factory reset) are available in the User Manual of the Dell monitor.

* If a mechanical monitor power button, press the button in for 8 seconds (clears any residual power in the circuits). If not a mechanical power button, just wait 8 seconds

The floating dialog box should appear on screen against a black background. While in self-test mode, the power LED remains white. Also, depending upon the selected input, one of the dialog boxes shown below will continuously scroll through the screen.

Your monitor has a BID that helps you determine if the issue you are seeing is an inherent problem with your monitor, or with your computer, video card, video card driver, or cable.

If the BID full colored screens do not show the issue, the monitor is functioning. The problem is with either the computer, video card, video card driver, or cable.

If the BID full colored screens did show the issue, create a thread on the Monitors Forum board and post pictures of the BID full colored screens showing the issue.

Our new line of 10.1” TFT displays with IPS technology are now available! These 10.1” IPS displays offer three interface options to choose from including RGB, LVDS, and HDMI interface, each with two touchscreen options as capacitive or without a touchscreen.

The new line of 3.5” TFT displays with IPS technology is now available! Three touchscreen options are available: capacitive, resistive, or without a touchscreen.

Cable wire harness tester,lcd display electric cable test, network cable tester on sale Specification Model HPS9810 HPS9820 Features Displayer TFT true color LCD display Display Language Optional operation interface in English and Chinese Measurement function Test Pin 80pin 128pin Measurement Speed One million pin /s Detection Type Single ended wiring harness,Double ended wire harness,Automotive wiring harness and so on Test Item Short,Open,Miss,Instantaneous short circuit,Instantaneous open circuit, Unilateral point measurement function Test Mode Auto,Manual Swing Test Manual mode is effective,Swing delay:5s-50s Data entry mode Self-learning standard wire sample Learning data storage store 3 kinds of different standard wire connection data Pin search Find points quickly and fixture of short circuit and open circuit detection Statistics Function The system provides statistical functions, and provides statistical analysis of the qualified rate and the defective items. Test signal DC signal source 5VDC DC current source 20mA,Max Sorting and interfaces Sorting Function GD/NG indicator light and Buzzer alarm, Text Tips Beep Pass/fail/off Interface RS-232C interface(optional),Handler interface(optional) General Specification Working Environment 0°C -40°C ,≤90%RH Power Supply 198V -242V(AC),47.5Hz -63Hz Power Consumption ≤30 VA Detailed Description Application ♦ Various types of terminal lines ♦ Wire harness and cable ♦ USB and Computer peripheral wire ♦ Wire order complex wiring harness for vehicle manufacturing industry such as cars, electric cars manufacturing industry Package & Shipping

Warranty(Year):1-yearCertification:ce, RoHSColor:blackDisplay Ratio:4:3Series:For BusinessAspect Ratio:4:3Screen Type:LCDPixel Pitch:0.276mmHorizontal Viewing Angle:170°Built-in Speaker:NoVertical Viewing Angle:160°After-sales Service:Free spare partsProducts Status:NewApplication:Desktop, Hotels,Shops,Bars,Coffee,Department Store,Shopping etcResponse Time:6msInterface Type:RS232CContrast Ratio:700:1Widescreen:NoPanel Type:TFTBrand Name:CaravPlace of Origin:Guangdong, ChinaFeature:Touch ScreenUse:For BusinessRatio:4:3Item:17"" touch screen monitorTouch type:10 point capacitive touch panelResolution:1280*1024(max)Power adaptor:110-240V/50-60HZ AC power inputViewing angle:Horizon: 170° Vertical: 160°Cetificate:CE/ROHS/EMC

AIO-1589 is a true flat aluminum housing POS. With classical 15"display screen and stable metal stand. Good quality at low cost make this model be our top-selling model. It has a variety of add-on options including integrated MSR or fingerprint reader, 2x20 VFD customer display, scanner and an integrated rear 7"LCD. it could be widely used in supermarket, shops, restaurant, hotel, salon, etc.

A: Each POS machine will ageing test 48 hours ,to guarantee all POS machine are in the perfect condition before shipment .we also accept the inspection by the third part you  appointed.

This invention relates to a method and apparatus for testing TFT-LCD"s (thin-film transistor liquid crystal displays) used as active-matrix color LCD"s.

Recently active-matrix LCD"s are extensively used as color displays. The active-matrix LCD writes necessary signals into the liquid crystal only for a given short period of time, holding the written signals during other times by keeping open the gate of the input circuit to liquid crystal. The feature of the active-matrix LCD is that the liquid crystal serves as a dynamic memory.

To ensure that the gate is kept open only for the length of time required for the writing of signals and closed during other times, TFT"s (thin-film transistors) or FET"s (field-effect transistors) are commonly used.

As schematically shown in FIG. 1, a TFT-LCD has many pixels, with a correspondingly large number of TFT"s 4 gate lines 3 and data lines 5 allocated to each pixel.

However, there is no sure guarantee that the TFT"s 4 always function normally, they are properly connected to the data lines 5 and/or gate lines 3, and the data and gate lines are kept in proper relationship.

Nevertheless, no efficient testing method has been established for TFT-LCD"s. Such being the case, most TFT-LCD"s have conventionally been assembled either without such preliminary test or, at best, after checking the relationship of each TFT with its peripheral lines.

One of the methods so far proposed discharges the electricity stored by applying voltage through a data line to an LCD cell capacitor (or an auxiliary capacitor connected in parallel thereto) by controlling the on-off action of a TFT and checks the normality of the individual connections therein by measuring the amount of electric charge induced by the discharging.

The object of this invention is to provide a simple and efficient method and apparatus for checking the normality of the individual elements of TFT-LCD"s mentioned before without employing an integrating capacitor and other associated apparatus.

To achieve the above object, a method for testing an active color TFT-LCD according to this invention comprises the steps of turning on a TFT, charging the cell capacitor thereof through a data line, turning off the TFT but maintaining the charged condition, turning off the TFT again, discharging through a resistor connected to the grounding side through the source and drain of the TFT, and judging whether the TFT functions normally and the elements therein are properly wired by the waveform of current or voltage induced by the discharge.

An apparatus for performing the test just described according to this invention comprises a waveform detector to determine the waveform of an electric current passing through a resistor connected to the source side of the TFT or the waveform of a voltage at both ends of the same resistor.

FIG. 3 is a graphical representation of a voltage waveform snowing the operational principle of the individual elements to be tested by the method and apparatus of this invention.

FIG. 4 shows a diagram of a TFT-LCD circuit whose data line is disconnected and a graphical representation of an output from the detecting side thereof at (a) and (b), respectively.

FIG. 5 shows a diagram of a TFT-LCD circuit whose gate line is disconnected and a graphical representation of an output from the detecting side thereof at (a) and (b).

FIG. 6 shows a diagram of a TFT-LCD circuit whose data and gate lines are short-circuited and a graphical representation of an output from the detecting side thereof at (a) and (b).

FIG. 7 shows a diagram of a TFT-LCD circuit whose gate and drain are short-circuited and a graphical representation of an output from the detecting side thereof at (a) and (b).

FIG. 8 shows a diagram of a TFT-LCD circuit whose source and drain are short-circuited and a graphical representation of an output from the detecting side thereof at (a) and (b).

FIG. 9 shows a diagram of a TFT-LCD circuit whose gate and gate line and drain are short-circuited and a graphical representation of an output from the detecting side thereof at (a) and (b).

FIG. 16 is a graphical representation of different voltages impressed into different points of a TFT-LCD showing the operational principle of a seventh embodiment of this invention at (a) and (b).

FIG. 17 is a graphical representation of different voltages discharged from different points of a TFT-LCD showing the operational principle of a seventh embodiment of this invention at (a) and (b).

FIG. 18 is a schematic illustration of the segments of a TFT-LCD divided along the gate and data lines thereof showing the configuration of a seventh embodiment of this invention.

FIG. 2 shows a cell capacitor Cs composed of a charge of one liquid crystal cell according to this invention and an auxiliary charge applied when TFT"s are arrayed (actually, the auxiliary charge itself constitutes the cell capacitor Cs when TFT"s are arrayed, and the auxiliary charge and the charge of a liquid crystal cell constitute the capacitor Cs when liquid crystal has been filled in each cell), a TFT connected through the drain side thereof, a data line connected to the source side of the TFT, a gate line connected to the gate side of the TFT, a first switch Sd interposed between a resistor Rg connected to the source side of the TFT and the data line, a waveform detector 11 to check the waveform of a current passing through the resistor Rg, and a second switch Sr interposed between the resistor R and the waveform detector 11.

After the pulse of the gate voltage VG has passed through and the TFT goes off, the resistance between the source and drain of the TFT becomes 105 to 106 times greater than that built up while the TFT is turned on by the gate voltage VG. Therefore, the cell capacitor Cs remains charged, with the charge held thereby decreasing only slowly through leakage.

If the first switch Sd is turned off and the switch Sr between the drain and the waveform detector is turned on when the TFT goes on again between the source and drain thereof with the passage of a pulse of the gate voltage VG, the charge held in the cell capacitor C, is discharged through the resistor Rg connected to the drain and source.

The resistor Rg is a resistor that is provided between the drain of each TFT and a ground connection including a guard ring while the guard ring is connected to each terminal during the manufacture of a TFT-LCD and artificially connected for the convenience of measurement by the waveform detector 11 when the guard ring is disconnected. As such, the resistance offered by the resistor Rg is smaller than about 1/100 of the resistance (Ron) that normally exists between the source and drain when the TFT is on.

Now that the volume of the cell capacitor Cs is known, the cell capacitor, gate line and data line of the TFT being tested prove to be properly connected if the time constant of the current wave passing through the resistor Rg agrees with the predicted value.

If, by contrast, the time constant T of the discharge-induced voltage or current changes and the waveform thereof disagrees with the predicted one, the value of the resistance Ron or the volume of the cell capacitor Cs should be construed as deviating from the specified value. Such deviation indicates the presence of connection irregularity in or around the TFT.

If the cell capacitor Cs has stored no electricity therein, no current flows through the resistor Rg which, in turn, indicates the presence of irregularity in the connection between the TFT and the gate or data line.

When testing the function and connection of the TFT-LCD"s corresponding to all pixels by the use of a relay, the gate lines corresponding to the horizontal rows of the TFT"s and the data lines corresponding to the vertical rows of the TFT"s are switched one by one, as will be discussed later in the description of a first embodiment of this invention.

If the data line between TFT2 and TFT3 is disconnected as shown at (a) in FIG. 4, no waveform to show the presence of discharge appears at Cs1 and Cs2 which are not charged, as shown at (b) in FIG. 4.

When the gate line is disconnected between TFT1 and TFT2 as shown at (a) in FIG. 5, Cs1 and Cs2 are not charged and, therefore, show no waveform of discharge.

When the gate line connected to TFT2 is short-circuited to the data line as shown at (a) in FIG. 6 and to the power supply, the voltage applied on the gate line itself appears at the data terminal as shown at (b) in FIG. 6 because the data line is connected to the gate line.

When TFT1 and TFT3 correspond to gate lines not short-circuited to other data lines, the data lines are grounded through the short-circuited points even when the gate lines are connected to the power supply. Accordingly, horizontal outputs produced by the grounding voltage appear as shown at TFT1 and TFT2 at (b) in FIG. 6.

When the gate and source of TFT2 are short-circuited, an output waveform identical to the one for a short-circuit between the data and gate lines appears because the power supply from the gate line is measured through TFT3.

In this case, it is necessary to determine whether a saturated output as shown at TFT2 at (b) in FIG. 6 is due to a short-circuit between the data and gate lines or between the gate and source of the TFT by checking through TFT2.

When the gate and drain of a TFT is short-circuited as shown at (a) in FIG. 7, the data and gate lines are connected through the gate and drain of the TFT. When discharge output is determined while the gate line is on, an output divided by resistance Ron that appears when the TFT is on and resistance Rg against detection, which is expressed as Rg /(Ron +Rg), appears.

When the source and drain of a TFT is short-circuited as shown at (a) in FIG. 8, Cs cannot be charged with the voltage or current from the gate line. Consequently, no waveform of discharge appears.

Because there is a combined capacity obtained through a TFT between the gate and data lines, however, a curve of rapid extinction (which is generally called a sneak curve of gate-applied voltage) appears as shown at (b) in FIG. 8.

When a cell capacitor Cs does not function properly, drain of a TFT and the capacitor Cs are short-circuited, with both electrodes thereof short-circuited, or when the neither charging nor discharging is possible. Then, an output waveform shown at (b) in FIG. 8 appears.

In this instance, it is necessary to determine whether the output waveform is due to a short-circuit between the source and drain of a TFT, or a short-circuit between both electrodes of the capacitor Cs, or a short-circuit between the drain of a TFT and the capacitor Cs.

When the gate of a TFT and the gate line are disconnected, the capacitor Cs is not charged through a TFT, as a consequence of which no discharge waveform appears.

However, the resulting discharge output is smaller than the one due to a short-circuit between the source and drain or the one due to a short-circuit of the capacitor Cs. When the source side of a TFT and the data line are short-circuited, the capacitor Cs is charged and discharged, with an output waveform shown at (b) in FIG. 9 obtained.

As is obvious from the above, the function of a TFT-LCD and the connection of its wiring can be roughly checked by analyzing the waveform of discharge outputs.

Switches Sg1, Sg2, . . . Sgm are provided to the gate lines G1, G2, . . . Gm connected to the horizontal rows of the TFT"s corresponding to the individual pixels, switches Sd1, Sd2, . . . Sdn to the data lines D1, D2, . . . Dn connected to the vertical rows thereof, and switches Sr1, Sr2, . . . Srn to the data lines connected to the waveform analyzer.

By making and breaking the switches Sg1, Sg2, . . . Sgm, switches Sd1, Sd2, . . . Sdn, and switches Sr1, Sr2, . . . Srn shown in FIG. 10, one after another, using a relay, whether or not the TFT"s corresponding to the individual pixels are properly connected can be determined efficiently.

The resistor Rg is provided on each data line between a junction with the relay and a junction with the ground to facilitate the measurement of the discharge output. To minimize measurement errors, the resistance the resistor Rg offers is not more than approximately 1/100 of the resistance Ron that is offered when a TFT is on.

Normal operation of all TFT"s are assured when all cell capacitors are charged as shown at (a) in FIG. 11 and show normal waveforms as shown at (b) in the same figure.

When time constant T deviates at several spots as shown at (c) in FIG. 11, either or both of TFT and LCD are out of order. If no waveform is shown, in particular, the TFT in the deviating spot is disconnected from either the gate line or data line.

Normal operation of all TFT"s is assured when the gate-line-connected cell capacitors in alternate horizontal rows are charged as shown at (a) in FIG. 12 and show normal discharge waveforms as shown at (b) in the same figure.

Proper connection of at least charged TFT"s is assured when the date-line-connected cell capacitors in alternate vertical rows are charged and discharged as shown at (a) in FIG. 13 and show normal discharge waveforms as shown at (b) in the same figure.

The overall condition of a TFT-LCD can be inspected by the use of a display panel corresponding to the arrangement of the individual TFT"s. Irregularities can be readily determined from an image reproduced on the display panel.

As such, the function and connection of all elements in a TFT-LCD can be checked by determining whether the detected output of discharge voltage or current is between the upper and lower limits shown in FIG. 14.

In the fifth embodiment, switches Sg1, Sg2, . . . Sgm are provided to the gate lines G1, G2, . . . Gm connected to the horizontal rows of the TFT"s corresponding to the individual pixels, switches Sd1, Sd2, . . . Sdn to the data lines D1, D2, . . . Dn connected to the vertical rows thereof, and switches Sr1, Sr2, . . . Srn to the data lines connected to the waveform analyzer, as shown in FIG. 10. By making and breaking the switches Sg1, Sg2, . . . Sm, data switches Sd1, Sd2, . . . Sdn, and relay switches Sr1, Sr2, . . . Srn using relays, whether the TFT"s corresponding to the individual pixels are properly connected can be efficiently checked one after another. An oscilloscope serving as the waveform detector 11 is connected to the relay side. Then, the function and connection of the individual elements can be checked by determining whether the waveforms of discharge that appear on the oscilloscope each time the data and gate lines are switched are between the maximum and minimum outputs as shown in FIG. 14.

Accordingly, the discharge outputs of the TFT"s and LCD"s distant from the actuating point on the gate side do not exhibit a typical curve of exponential function as shown at (a) in FIG. 17, but a curve with a slow rise and a gentle curve of discharge as shown at (b) in the same figure.

Therefore, the upper and lower limits of the normal output discharge curves of the fifth and sixth embodiments differ with the position of the TFT-LCD"s. Basically, as such, it is desirable to show the upper and lower limits of discharge output for each gate line and data line.

In the seventh embodiment, the TFT-LCD"s are divided into groups according to the order of the gate and data lines as shown in FIG. 18, and the upper and lower limits of normal discharge output are specified for each group.

The TFT-LCD"s connected to each data and gate line are usually divided into three to five groups, which makes the total number of groups nine (3×3) to twenty five (5× 5), though the number varies with the number of the gate and data lines.

When determined on the basis of the time during which leakage resistance Roff is expressed as e=E. exp(-t/Cs Roff) the TFT is off, the discharge voltage passing over the (wherein E=the voltage between the two electrodes of the capacitor Cs when the TFT is off).

(Here, t is the time passed after the point at which the TFT is turned on. The resistance Rg shown in FIG. 2 is neglected as it is much smaller than Roff.)

As is obvious from the above, the method of this invention, though simple in design, permits quickly checking the function of a TFT-LCD, the connection between each TFT and peripheral circuits and between the gate lines in individual horizontal rows and the data lines in individual vertical rows, and the presence of short-circuits between the gate lines and the data lines.

Particularly, the method that specifies the maximum and minimum discharge outputs not only makes the above checks but also quickly and easily checks whether the leakage resistance Roff that appears when the TFT is turned off is normal.

The EN220 from Everfocus is a 5.6" TFT LCD CVBS test monitor & service kit. The EN220 test monitor supports CVBS analog connection. Its compact size and rechargeable battery, make this a versatile device for any installer that is looking for an efficient time saving tool for initial set up and testing.