Backlight module and method for detecting electrostatic damage thereof

A backlight module is disclosed. The backlight module comprises a circuit board, at least one light source disposed on the circuit board, and a positive probe-point and a negative probe-point, both provided on the circuit board. The positive and negative probe-points are electrically connected to the light source, and the positive probe-point and the negative probe-point are electrically connected with a current dividing element so that the light source is connected in parallel with the current dividing element. The positive probe-point and the negative probe-point are also collectively configured to detect an electrostatic damage of the backlight module.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of priority to Chinese Patent Application No. 201310573290.4, filed with the Chinese Patent Office on Nov. 15, 2013 and entitled “BACKLIGHT MODULE AND METHOD FOR DETECTING ELECTROSTATIC DAMAGE THEREOF”, the content of which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a field of backlight module techniques in liquid crystal displays, and in particularly to a backlight module and a method for detecting an electrostatic damage thereof.

2. Technical Background

Liquid crystal displays are widely used in various electronic communication products, and a backlight module is one of the important components in the liquid crystal display. At present, light emitting diodes (LEDs) are generally used as the light sources in the backlight module. Static electricity is likely generated in various manners in assembling the backlight module, e.g., during stages of producing the LEDs, welding the LEDs to a Flexible Printed Circuit (FPC) board, assembling an LED strip to the backlight module, and the like. During the entire production process from the LED chip production to the assembling of the whole electronic product, an electrostatic damage might be caused to the LEDs by operators, machines, materials and environments, and the prevention of the electrostatic damage has become an emphasis in the industry because the LED, which is a semiconductor element, is vulnerable to the static electricity since the PN junction thereof is directly exposed to the environment. When being applied by a normal operation current, an LED subjected to a severe electrostatic damage exhibits defects such as a current leakage or even cannot emit light, but an LED subjected to a slight electrostatic damage generally will not exhibit any abnormality. However, the LED subjected to a slight electrostatic damage already has a certain potential risk, and would exhibit defects such as darkened emitted light or an increased current leakage or even cannot emit light after the LED is subjected to a secondary electrostatic damage.

Since the electrostatic damage cannot be completely avoided so far from the production stages of Liquid Crystal Display Modules (LCMs), measures have been taken in the various production stages to detect whether the LED emits light normally, in order to remove the defective LED damaged by the static electricity. If damaged severely, the LED would become a failed light (that is, the LED is completely damaged, for example, by the static electricity and cannot operate normally), which may generally be found by directly detecting whether the LED normally emits light after the normal operation current is applied to the LED. As shown inFIG. 1, the LED strip or the backlight module (not shown) is connected to a normal power supply3through a lighting fixture2, and an LED from the LED strip or the backlight module may be determined as a failed light or not by detecting whether the LED emits light normally.

In addition, an LED subjected to a slight electrostatic damage, if applied by the normal operation current, can also emit light normally and hence it is not possible to determine whether the LED has been subjected to the slight electrostatic damage. Nonetheless, the LED subjected to the slight electrostatic damage cannot emit light normally if a low current is applied thereto, thus, it is applicable to apply the low current to the LED in order to detect whether the LED has been slightly damaged by the static electricity. If any LED subjected to the slight electrostatic damage is not found, the LED would exhibit defects such as darkened emitted light or an increased current leakage or even cannot emit light, when the LED is subjected to a secondary electrostatic damage, as a result, the whole backlight module and the LCM cannot operate normally, resulting in lower yields and high production costs.

FIG. 2shows the existing LED detection techniques for detecting whether an LED has been damaged by the static electricity. As shown, in Step S1, the low current-based detection is conducted on an individual LED chip to determine whether the individual LED chip emits light normally; in Step S2, the low current-based detection is conducted on an LED strip assembled by LED chips to determine whether the LED strip emits light normally; in Step S3, the low current-based detection is conducted on a backlight module assembled by LED strips to determine whether the backlight module emits light normally; but in Step S4, the low current-based detection can be conducted neither for the LCM assembled by the backlight modules, nor in the subsequent steps. The reason lies in that, after the backlight modules are assembled into the LCM, the current supplied to the LED is limited to a preset rated current having an unchangeable amount, which is a normal operation current instead of a low current, thus the low current-based detection cannot be conducted. However, in the step of assembling the backlight modules into the LCM as well as the subsequent steps, the electrostatic damage is inevitable, but the low current-based detection cannot be conducted for the LEDs in the LCMs, so that potential defective LEDs subjected to the electrostatic damage lead to a risk of the quality of the LCM.

BRIEF SUMMARY OF THE INVENTION

One embodiment is a backlight module. The backlight module comprises a circuit board, at least one light source disposed on the circuit board, and a positive probe-point and a negative probe-point, both provided on the circuit board. The positive and negative probe-points are electrically connected to the light source, and the positive probe-point and the negative probe-point are electrically connected with a current dividing element so that the light source is connected in parallel with the current dividing element. The positive probe-point and the negative probe-point are also collectively configured to detect an electrostatic damage of the backlight module.

Another embodiment is method of detecting an electrostatic damage of a backlight module. The method comprises providing a current dividing element, and providing a backlight module. The backlight module comprises a circuit board and at least one light source disposed on the circuit board. The method also includes providing a detection power supply configured to apply a first detection current, applying the first detection current to the light source by electrically connecting the detection power supply with the light source, and connecting the current dividing element in parallel with the light source so that a second detection current is applied to the light source, where the second detection current is divided from the first detection current. The method also includes determining, based on the second detection current applied on the light source, whether the light source is damaged.

For the problems presented in the prior art, an object of the invention is to provide a backlight module, a method for detecting an electrostatic damage of the backlight module, and a liquid crystal module.

According to an exemplary embodiment of the invention, there is provided a backlight module, and the backlight module includes: a circuit board; at least one light source disposed on the circuit board; and at least one positive probe-point and at least one negative probe-point, both provided on the circuit board and electrically connected to the light source; where the positive probe-point and the negative probe-point are electrically connected with a current dividing element so that the light source is connected in parallel with the current dividing element, to detect an electrostatic damage of the backlight module.

According to an exemplary embodiment of the present invention, there is provided a method for detecting an electrostatic damage of a backlight module, and the method includes steps of:

providing a current dividing element;

providing a backlight module, which includes: a circuit board and at least one light source disposed on the circuit board;

providing a detection power supply configured to apply a first detection current; applying the first detection current on the light source, by electrically connecting the detection power supply with the light source;

connecting the current dividing element in parallel with the light source, so that a second detection current which is a low current applied on the light source is divided from the first detection current; and

determining, by the second detection current applied on the light source, whether the light source is damaged, and if a light source emits light normally, the light source has not been subjected to the electrostatic damage; else if the light source does not emit light normally, the light source has been subjected to the electrostatic damage.

According to an exemplary embodiment of the present invention, there is provided a liquid crystal display module which includes the above backlight module.

With the technical solution described above, the present invention discloses a backlight module and a method for detecting an electrostatic damage thereof, where the backlight module can achieve the detection for the electrostatic damage of the LED under the low current condition even after the backlight module is assembled into the liquid crystal display module, as compared with the prior art.

DETAILED DESCRIPTION OF THE INVENTION

The technical solutions in the embodiments of the present invention are clearly and completely described below in combination with the drawings. Obviously, the described embodiments are some instead of all embodiments of the present invention. All other embodiments obtained in light of the described embodiments of the invention by those skilled in the art without any creative work should fall within the protection scope of the present invention.

The present invention discloses a backlight module and a method for detecting an electrostatic damage thereof, where the backlight module includes a backlight module, a circuit board; at least one light source disposed on the circuit board; and at least one positive probe-point and at least one negative probe-point, both provided on the circuit board and electrically connected to the light source; where the positive probe-point and the negative probe-point are connected with a current dividing element so that the light source is connected in parallel with the current dividing element, to detect an electrostatic damage of the backlight module. The backlight module can achieve the detection for the electrostatic damage of the LED under the low current condition even after the backlight module is assembled into the liquid crystal display module, as compared with the prior art.

First Embodiment

As shown inFIGS. 3 to 5, the present invention discloses a backlight module111, which includes a circuit board12and at least one light source11disposed on the circuit board12. The light source11is generally composed by LEDs, which may be connected in series with each other, or may be formed by parallel LED groups each including serially connected LEDs; and the circuit board12includes an FPC board.

As shown inFIG. 4(which shows a partially enlarged view of the portion enclosed by a dashed line inFIG. 3), the light source module111further includes at least one positive probe-point13and at least one negative probe-point14, which are both disposed on the circuit board12(specifically disposed on a projecting portion A of the circuit board12), and are electrically connected to the light source11, that is, conductive wires are arranged on the circuit board12to conduct the positive probe-point13and the negative probe-point14with the light source11. The positive probe-point13and the negative probe-point14arranged on the board12are configured for electrically connecting to a current dividing element112so that the light source11is connected in parallel with the current dividing element112, to detect the electrostatic damage of the backlight module.

Referring toFIG. 3again, the backlight module111further includes detection pins15and16provided on the circuit board12and electrically connected to the light source11, that is, conductive wires are arranged on the circuit board12to conduct the detection pins15and16with the light source11. The detection pins15and16are generally disposed on the projecting portion A of the circuit board12, and configured to connect an external detection power supply11to detect the electrostatic damage or a failed light in the light source11.

As shown inFIG. 3, the backlight module111is structural separately from the current dividing element112in the present embodiment.

As shown inFIG. 5, the current dividing element112includes at least one first resistor19, at least one positive probe17, and at least one negative probe18. The first resistor19is electrically connected to both the positive probe17and the negative probe18, that is, both ends of the first resistor19are respectively connected to the positive probe17and the negative probe18by conductive wires. It is noted that the first resistor19includes at least one first variable resistor or at least one first constant resistor.

Referring toFIGS. 3 and 5again, to detect the electrostatic damage of the backlight module111, the positive probe17is connected to the positive probe-point13and the negative probe18is connected to the negative probe-point14, so that the first resistor19is connected in parallel with the light source11, resulting in an equivalent circuit diagram shown inFIG. 10. Specifically, to detect the electrostatic damage of the backlight module111, the external current is typically applied directly to the light source11by an external power supply connected to the detection pins15and16, in order to determine whether any electrostatic damage has occurred to the light source11. If the amount of the current applied by the external power supply is uncontrollable, especially if the amount of the current applied by the external power supply is large, any light source subjected to the slight electrostatic damage cannot be detected, and such light source will exhibit defects such as darkened emitted light or an increased current leakage or even cannot emit light after the light source suffers from a secondary electrostatic damage. To solve the problem caused by the uncontrollable amount of the current applied by the external power supply, the first resistor19, which is the first variable resistor with adjustable resistance, is connected in parallel to the light source11on the backlight module111in the present embodiment, so that the external current applied on the light source11can be divided by the first resistor19, and a low current for detecting the electrostatic damage suffered by the light source is divided from the external current by adjusting the amount of the resistance of the first resistor19. Alternatively, if the first resistor19is a first constant resistor, the division of the low current from the external current can be implemented by replacing the first resistor19with a constant resistor having different resistance.

It is also noted that in the case of a plurality of light sources11which are typically LEDs, if the LEDs are connected in series with each other, the low current for detecting the presence of an electrostatic damage of any LED generally has an amount of 0.5-1 mA, that is, the amount of the current applied on each of the serially connected LEDs is 0.5-1 mA; otherwise, if the light sources11are composed by parallel LED groups each of which is formed by a plurality of serially connected LEDs, the low current for detecting the presence of an electrostatic damage in the LED has such an amount that the current applied on each of the serially connected LEDs in each of the LED groups has an amount of 0.5-1 mA, as such, the amount of the low current is not constant.

Further, the positive probe-point13and the negative probe-point14are provided on the projecting portion A of the circuit board12, so that the positive probe-point13and the negative probe-point14are exposed even after the assembly of the backlight module111into the liquid crystal display module since the positive and negative probe-points are both located on the projecting portion of the circuit board12. As such, it is easy and convenient to connect the current dividing element112with the positive probe-point13and the negative probe-point14to detect the electrostatic damage of the backlight module111.

Second Embodiment

Base on the disclosed first embodiment of the present invention, the invention further discloses a backlight module211. The backlight module211includes: a circuit board22; at least one light source21disposed on the circuit board22; detection pins25and26disposed on a projecting portion B of the circuit board22; and at least one positive probe-point23and at least one negative probe-point24, which are both provided on the circuit board22, (specifically on a projecting portion B of the circuit board22), and are electrically connected with the light source21. The light source21is generally composed by LEDs which may be connected in series with each other, or may be formed by parallel LED groups each including serially connected LEDs; and the circuit board22includes an FPC board. The positive probe-point23and the negative probe-point24arranged on the board22are configured for electrically connecting to a current dividing element so that the light source21is connected in parallel with the current dividing element, to detect the electrostatic damage of the backlight module211.

As shown inFIG. 7, the present embodiment is different from the first embodiment in that the backlight module211is formed integrally with the current dividing element.

As shown inFIG. 8(which is a partially enlarged view of the portion enclosed by the dashed line inFIG. 7), the current dividing element includes at least one second resistor29, which includes at least one second variable resistor or at least one second constant resistor, disposed on a side of the circuit board22, preferably disposed on the projecting portion B of the circuit board22, but the present invention is not limited thereto. When the detection of the electrostatic damage is not conducted for the backlight module211, the second resistor29is disconnected from the light source21, resulting in an equivalent circuit diagram shown inFIG. 9in which the electrical circuit connections may be realized by the arranged conductive wires on the circuit board21. When a normal operating voltage is applied across light source21, the light source21is in a normal operating state, and the second resistor29is disconnected from the light source21.

Referring toFIG. 8again, to detect the electrostatic damage of the backlight module211, the positive probe-point23is connected to the negative probe-point24by an external conductive wire20, so that the second resistor29is connected in parallel with the light source21, resulting in an equivalent circuit diagram shown inFIG. 10. That is, The connection between the positive probe-point23and the negative probe-point24by the external conductive wire20enables the positive probe-point23and the negative probe-point24to serve as a switch, as a result, when the positive probe-point23and the negative probe-point24are connected with each other, the second resistor29is connected in parallel with the light source for the purpose of current division; and when the positive probe-point23and the negative probe-point24are disconnected from each other, the second resistor29is not in electrical connection with the light source21. The current dividing element, i.e. the second resistor29, is formed directly on the circuit board22, so that the electrostatic damage of the backlight module211can be detected more simply.

The present embodiment is based on the first embodiment, and parts in the present embodiment the same as those of the first embodiment will not be described again herein.

Third Embodiment

As shown inFIGS. 3 and 11, based on the disclosed first embodiment of the present invention, the present invention further discloses a method for detecting an electrostatic damage of a backlight module, and the method includes Steps S101to S105as follows.

In Step S101, a current dividing element112is provided. The current dividing element112includes at least one first resistor19, at least one positive probe17and at least one negative probe18, where the first resistor19is electrically connected with the positive probe17and the negative probe18, that is, both ends of the first resistor19are respectively connected to the positive probe17and the negative probe18by conductive wires. It is noted that the first resistor19at least includes a first variable resistor or a first constant resistor.

In Step S102, a backlight module111is provided. The backlight module111includes: a circuit board12(which is typically a Flexible Printed Circuit board); at least one light source11disposed on the circuit board12; and the positive probe-point13and the negative probe-point14, which are both disposed on the circuit board12, specifically on the projecting portion A of the circuit board12, and are electrically connected with the light source11. The backlight module111further includes detection pins15and16provided on the circuit board12and electrically connected to the light source11, that is, the circuit board12is provided with conductive wires for conducting the detection pins15and16with the light source11.

In Step S103, a detection power supply is provided to apply a first detection current I1(the amount of which may be constant, or be preset as unchangeable) to the light source11, that is, the detection power supply is electrically connected with the light source11, in particularly, the detection power supply applies the first detection current I1to the light source11through the detection pins15and16on the circuit board12.

In Step S104, the current dividing element112is connected in parallel with the light source11so that a second detection current I2which is a low current applied on the light source11is divided from the first detection current I1, in particularly, the positive probe17of the current dividing element112is electrically connected with the positive probe-point13on the circuit board12, and the negative probe18of the current dividing element112is electrically connected with the negative probe-point14on the circuit board12, to connect the first resistor19in parallel with the light source11, so that the second detection current I2which is a low current applied on the light source11is divided from the first detection current I1.

In Step S105, it is determined, through the second detection current I2applied on the light source11, whether the light source11has been subjected to an electrostatic damage. If the light source11emits light normally, the light source11has not been subjected to the electrostatic damage; and if the light source11does not emit light normally, the light source11has been subjected to the electrostatic damage. The second detection current I2is the low current for determining whether the electrostatic damage has occurred to the light source11, and is smaller than the first detection current I1.

Referring toFIGS. 3, 5, and 11again, in S104, to detect the electrostatic damage of the backlight module111, the positive probe17is connected to the positive probe-point13and the negative probe18is connected to the negative probe-point14, so that the first resistor19is connected in parallel with the light source11, resulting in an equivalent circuit diagram shown inFIG. 6. Specifically, to detect the electrostatic damage of the backlight module111, the first detection current I1(external current) is typically applied directly to the light source11by an external power supply through the detection pins15and16, in order to determine whether any electrostatic damage has occurred in the light source11. If the amount of the first detection current I1is uncontrollable or is preset as unchangeable, especially if the amount of the first detection current I1is large, any light source subject to the slight electrostatic damage cannot be detected, and, such light source will exhibit defects such as a darkened emitted light, or an increased current leakage or even cannot emit light after the light source suffers from a secondary electrostatic damage. To solve the problem caused by the uncontrollable amount of the first detection current I1, the first resistor19, which is the first variable resistor with adjustable resistance, is connected in parallel to the light source11on the backlight module111in the present embodiment, so that the first detection current I1applied on the light source11can be divided by the first resistor19, and the second detection12, which is a low current for detecting whether the electrostatic damage has occurred to the light source, is divided from the first detection current I1by adjusting the amount of the resistance of the first variable resistor19. Alternatively, if the first resistor19is a first constant resistor, the division of the low current from the first detection current I1can be implemented by replacing the first resistor19with a constant resistor having different resistance.

It is also noted that in S104and S105, in the case of a plurality of light sources11which are typically LEDs, if the LEDs are connected in series with each other, the low second detection current I2for detecting the presence of an electrostatic damage of any LED generally has an amount of 0.5-1 mA, that is, the amount of the current applied on each of the serially connected LEDs is 0.5-1 mA; otherwise, if the light sources11are composed by parallel LED groups, each of which is formed by a plurality of serially connected LEDs, the low second detection current I2for detecting the presence of an electrostatic damage in the LED has such an amount that the current applied on each of the serially connected LEDs in each of the LED groups has an amount of 0.5-1 mA, as such, the amount of the low second detection current I2is not constant.

Further, in S102and S104, the positive probe-point13and the negative probe-point14are provided on a projecting portion of the circuit board12, so that the probe-point13and the negative probe-point14are exposed even after the assembly of the backlight module111into the liquid crystal display module since the positive and negative probe-points are both located on the projecting portion A of the circuit board12. As such, it is easy and convenient to connect the current dividing element112with the positive probe-point13and the negative probe-point14to detect the electrostatic damage of the backlight module111.

Fourth Embodiment

As shown inFIGS. 7 to 10andFIG. 12, based on the disclosed second and third embodiments of the present invention, the present invention further discloses a method for detecting an electrostatic damage of a backlight module, and the method includes Steps S201to S205as follows.

In Step S201, a current dividing element is provided. The current dividing element includes at least one second resistor29. It is noted that the second resistor29includes at least a second variable resistor or a second constant resistor.

In Step S202, a backlight module211is provided. The backlight module211includes: a circuit board22(which is typically a Flexible Printed Circuit board); at least one light source21disposed on the circuit board22; and the positive probe-point23and the negative probe-point24, which are both disposed on the circuit board22, specifically on the projecting portion B of the circuit board22, and are electrically connected with the light source21. The backlight module211further includes detection pins25and26provided on the circuit board22and electrically connected to the light source21, that is, the circuit board22is provided with conductive wires for conducting the detection pins25and26with the light source21. The current dividing element provided on a side of the circuit board22is contained in the backlight module211. When the detection of the electrostatic damage is not conducted for the backlight module211, the second resistor29is disconnected from the light source21, resulting in an the equivalent circuit diagram shown inFIG. 9in which the electrical circuit connections may be realized by the arranged conductive wires on the circuit board21.

In Step S203, a detection power supply is provided to apply a first detection current I1(the amount of which may be constant, or be preset as unchangeable) to the light source21, that is, the detection power supply is electrically connected with the light source11, in particularly, the detection power supply applies the first detection current I1to the light source21through the detection pins25and26on the circuit board22.

In Step S204, the current dividing element is connected in parallel with the light source11so that a second detection current I2which is a low current applied on the light source21is divided from the first detection current I1, in particularly, with reference toFIG. 8again, the positive probe-point23is connected to the negative probe-point24by an external conductive wire20, to connect the second resistor29in parallel with the light source21, resulting in an equivalent circuit diagram shown inFIG. 10, so that the second detection current I2which is a low current applied on the light source21is divided from the first detection current I1.

In Step S205, it is determined, through the second detection current I2applied on the light source21, whether the light source21has been subjected to an electrostatic damage. If the light source21emits light normally, the light source21has not been subjected to the electrostatic damage; if the light source21does not emit light normally, the light source21has been subjected to the electrostatic damage. The second detection current I2is the low current for determining whether the electrostatic damage has occurred to the light source21, and is smaller than the first detection current I1;

It is noted that, to detect the electrostatic damage of the backlight module211, in Step S204, the connection between the positive probe-point23and the negative probe-point24by the external conductive wire20enables the positive probe-point23and the negative probe-point24to serve as a switch, as a result, when the positive probe-point23and the negative probe-point24are connected with each other, the second resistor29is connected in parallel with the light source, for the purpose of the current division; and when the positive probe-point23and the negative probe-point24are disconnected from each other, the second resistor29is not in electrical connection with the light source21. The current dividing element, i.e. the second resistor29, is formed directly on the circuit board22, so that the electrostatic damage of the backlight module211can be detected more simply.

In Steps S204and S205, in the case of a plurality of light sources21which are typically LEDs, if the LEDs are connected in series with each other, the second detection current I2generally has an amount of 0.5-1 mA; otherwise, If the light sources are composed by a parallel LED groups each of which is formed by a plurality of serially connected LEDs, the low second detection current I2for detecting the presence of the electrostatic damage in the LED has such an amount that the current applied on each of the serially connected LEDs in each of the LED groups has an amount of 0.5-1 mA, as such, the amount of the low second detection current I2is not constant. The amount of the second detection current I2can be controlled by adjusting the second variable resistor or replacing the second constant resistor.

The present embodiment is based on the second and third embodiments, and the parts in the present embodiment same as those of the second and third embodiments will not be described again herein.

Fifth Embodiment

As shown inFIG. 13, based on the disclosed first and second embodiments of the present invention, the present invention further discloses a liquid crystal display module1111which includes the backlight module111provided by the first embodiment or the backlight module211provided by the second embodiment. The liquid crystal display module1111further includes a liquid crystal display panel222. The liquid crystal display module1111has a function of low current-based detection for determining whether an electrostatic damage has occurred to the light source of the backlight module111or211of the liquid crystal display module1111, thus reducing the potential defective LEDs subjected to the electrostatic damage in the step for assembling the liquid crystal display module (LCM) and subsequent process steps, and improving the production yields.

The various sections in the specification are described in a progressive manner, and differences of the subsequent sections from the previous sections are illustrated. Therefore, the same or similar parts in various sections can be referred to each other.

The above disclosed embodiments are described for implementing or using the present invention by those skilled in the art. It will be apparent that various modifications can be made to these embodiments by those skilled in the art, and the general principles defined by the present invention can be implemented in other embodiments without departing from the spirit or the protection scope of the present invention. Therefore, the present invention is not limited by the embodiments shown herein, rather conforms to the broadest range in accordance with the principles and novelty characteristics disclosed.