JP3829560B2 - Display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a display device, and more particularly to a display device including an active matrix type liquid crystal panel such as TFT and TFD, and a simple matrix type liquid crystal panel such as STN, which detects the temperature of the liquid crystal panel and responds to the detected temperature. The present invention relates to a device having a function of controlling an applied voltage to the liquid crystal panel and thereby realizing an appropriate display state.
[0002]
[Background]
As a display device including a display unit that modulates a light beam emitted from a light source, a display device including a liquid crystal panel is known. Such a display device is used as a display device for car navigation, a portable or wall-mounted television image display device, a viewfinder of a video camera, and the like.
[0003]
In the liquid crystal panel constituting the display device described above, a change occurs between the applied voltage and the light transmission characteristic from the light source in accordance with the temperature change of the liquid crystal panel. May occur.
[0004]
For this reason, conventionally, the surface temperature of the liquid crystal panel is detected by a temperature compensation element such as a thermistor, and the voltage applied to the liquid crystal panel is determined using the characteristics of the temperature compensation element (for example, the B characteristic for a thermistor). Means are used to control and improve the display inconvenience of the liquid crystal panel.
[0005]
FIG. 8 shows a conventional example. In FIG. 8, a liquid crystal panel unit 101 is provided as a display unit. A temperature compensation circuit board 102 is provided in the vicinity of the liquid crystal panel unit 101, and a thermistor 103 as a temperature compensation element is mounted on the surface of the temperature compensation circuit board 102. The output of the thermistor 103 is connected to a display control board 104 provided separately from the temperature compensation circuit board 102. The display control board 104 includes a voltage control circuit that controls the voltage applied to the liquid crystal panel unit 101 in accordance with the temperature detected by the thermistor 103. The display control board 104 linearly controls the voltage applied to the liquid crystal panel unit 101 with respect to the detected temperature characteristic of the thermistor 103 (for example, the B characteristic of the thermistor), thereby performing display due to the influence of the temperature of the liquid crystal panel unit 101. The above inconvenience is improved.
[0006]
Here, the connection between the temperature compensation circuit board 102 and the display control board 104 will be described in more detail. As shown in FIG. 9, the display control board 104 includes a voltage control circuit 104a that controls the temperature compensation control described above, and A connector C1 for connecting the voltage control circuit 104a to the thermistor 103 is provided. The connector C1 is a 2-pin connector, and a circle with a symbol P indicates each connector pin. A fixed resistor 104b is connected in parallel with the thermistor 103 in the vicinity of the connector C1, and the temperature change characteristic of the thermistor 103 can be adjusted by changing the resistance value of the fixed resistor 104b.
[0007]
On the other hand, the temperature compensation circuit board 102 includes a 2-pin connector C2 for connecting the thermistor 103 to the voltage control circuit 104a. The connector C1 provided on the display control board 104 and the connector C2 provided on the temperature compensation circuit board are connected by the two-wire wire harness 105, whereby the voltage control circuit 104a and the temperature compensation element 103 are connected. Electrical continuity between them is ensured. The wire harness 105 is detachable by using connectors C1 and C2.
[0008]
[Problems to be solved by the invention]
However, in the above conventional example, when the wire harness 105 that connects the temperature compensation circuit board 102 and the display control board 104 is not correctly connected, the voltage control circuit 104a obtains a detection signal from the thermistor 103. This makes it impossible to perform appropriate temperature compensation control. In addition, since the connection terminal of the voltage control circuit 104a to the thermistor 103 is always short-circuited via the fixed resistor 104b, electrical continuity is ensured. Therefore, it is difficult to detect the connection failure of the wire harness 105 only by monitoring the signal of the connection terminal connected to the thermistor 103 by the voltage control circuit 104a. On the other hand, as a method of detecting the connection failure of the wire harness 105, the product is actually driven under each ambient temperature environment to check whether there is any defect in the display state, that is, correct temperature compensation control is performed. Although it is conceivable to detect a connection failure of the wire harness 105 by actually confirming whether it has been performed, it takes a long time to adapt the product to the ambient temperature environment, resulting in a huge man-hour increase. Not realistic.
[0009]
In addition, since such a temperature compensation control system is housed in the housing of the display device, if the wire harness 105 is attached without being properly connected, a connection failure will be discovered later, and this will be maintained. It took a lot of effort.
[0010]
Accordingly, an object of the present invention is to provide a display device that can quickly and easily know a state in which a harness that connects a display control board and a temperature compensation circuit board is not normally connected.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a display device according to the present invention includes a display unit that modulates a light beam emitted from a light source to form an optical image, and a temperature compensation element that detects a temperature in the vicinity of the display unit. A temperature control circuit board, a display control board including a voltage control circuit for controlling a voltage applied to the display unit in accordance with a detection signal of the temperature compensation element, and the temperature compensation circuit board and the display control board are electrically connected. And a connection failure detecting means for outputting a signal indicating that the display of the display unit is defective when a failure in electrical continuity of the connection device is detected. It is characterized by.
[0012]
According to the present invention as described above, since the display device includes the connection failure detection means, when a failure in electrical continuity of the connection device is detected, the display on the display unit becomes defective, and the electrical continuity of the connection device. Can be confirmed immediately. Therefore, it is possible to obtain a display device capable of reliably performing voltage control by the temperature compensation element by confirming the defect of the connection device before housing.
[0013]
In the above, it is preferable that the connection failure detection means described above is provided in the middle of the applied voltage supply line to the display unit or the power supply line to the light source.
[0014]
Here, as the above-mentioned “signal indicating that the display unit display is defective”, for example, the voltage supply of the applied voltage supply line on either the − side or the + side of the applied voltage supply line to the display unit is cut off. Or a signal for shutting off the power supply of the power supply line to the light source.
[0015]
That is, if the supply of the applied voltage to the display unit is interrupted, the display unit does not perform a normal display operation, so that it is possible to immediately detect a defective connection device. Further, if the power supply to the light source is cut off, the luminous flux is not supplied to the display unit, so that similarly, it is possible to immediately find a defect in the connection device.
[0016]
Further, when the connection device described above includes a pair of connectors provided on each of the display control board and the temperature compensation circuit board and a wire harness attached to each connector, the connection failure detection means displays the display The applied voltage supply line to the unit or the power supply line to the light source is preferably configured to pass through at least one of the pair of connectors.
[0017]
That is, if the connection failure detection means is configured in this way, when the wire harness is disconnected from the connector and the connection is defective, the applied voltage supply to the display unit or the power supply to the light source is immediately cut off. It becomes possible to simply configure the defect detection means.
[0018]
Furthermore, when the connection failure detection means is configured by applying the above-described applied voltage supply line or power supply line via a connector, the connection device can be configured as follows.
[0019]
(1) The connector provided on the display control board is a 4-pin connector, the connector provided on the temperature compensation circuit board is a 2-pin connector, and the wire harness is electrically connected to the 2-pin connector and the 2-pin connector. It is conceivable to include a jumper that shorts the remaining two pins of the 4-pin connector and the applied voltage supply line or the power supply line via this jumper.
[0020]
By configuring the connection device in this manner, it is possible to immediately detect a connection failure between the connector and the wire harness on the display control board with a jumper.
[0021]
Further, since the 2-pin connector is employed on the temperature compensation circuit board side, the temperature compensation circuit board does not become larger than necessary, and the temperature compensation circuit board can be arranged in a narrow space.
[0022]
(2) The connector provided on the display control board and the temperature compensation circuit board is a 4-pin connector, and the wire harness is configured to include four signal lines that connect the signal input / output terminals of each connector. Two of these signal lines connect the temperature compensation element and the voltage control circuit, and the other two signal lines are short-circuited on the temperature compensation circuit board side, and the applied voltage supply line or the power supply line is connected to the other two signals. You can go through a line. In this case, the other two signal lines can be short-circuited on the temperature compensation circuit board side by short-circuiting at the connector portion of the temperature compensation circuit board or by a wiring pattern formed on the temperature compensation circuit board. The structure to be made can be considered.
[0023]
By configuring the connection device in this manner, if any connector is disconnected from the wire harness, the applied voltage supply or the power supply is immediately shut off, so the connection device connection failure is reliably detected. be able to.
[0024]
In addition to configuring the connection failure detection means with the connector, wire harness, etc. of the connection device described above, the connection failure detection means is configured by mounting a circuit element connected in parallel with the temperature compensation element on the temperature compensation circuit board. You can also
[0025]
That is, a circuit element such as a fixed resistor connected in parallel with the temperature compensation element conventionally provided on the display control board is mounted on the temperature compensation circuit board. When conduction failure occurs, a part of the voltage control circuit on the display control board is opened. Therefore, by detecting this change in the terminal voltage with the voltage control circuit, it is possible to detect a failure in electrical connection of the connection device and output a signal indicating that the display is defective on the image display unit.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0027]
(1) Configuration of Display Device As shown in FIG. 1, the display device 11 includes a liquid crystal panel unit 30 including a liquid crystal panel 30a as a display unit, a backlight 40 serving as a back light source of the liquid crystal panel unit 30, and a liquid crystal The display control board 50 which controls the image etc. which are displayed on the panel unit 30 and the exterior case 60 which consists of the front case 61 and the back case 62 which accommodate and integrate these are provided.
[0028]
The liquid crystal panel unit 30 is provided on a liquid crystal panel 30a as a light modulation device that modulates a light beam from the backlight 40, a transparent substrate of the liquid crystal panel 30a, and an X-side driver for driving a liquid crystal driving element inside the transparent substrate. An IC and a Y-side driver IC (not shown) are provided on the back side of the liquid crystal panel 30a, hold the liquid crystal panel 30a in a predetermined position, diffuse the light flux from the backlight 40, and convert it into a substantially uniform surface light source. A diffusing plate 30b having a function and a metal panel shield frame 30c that covers the outer peripheral portion of the liquid crystal panel 30a, blocks EMI (electromagnetic interference), and suppresses the influence of external noise on the liquid crystal panel 30a. The The liquid crystal panel 30a is a TFD drive liquid crystal panel using a diode as a drive element.
[0029]
The backlight 40 emits a W-shaped fluorescent tube 41 serving as a light source of a back light source, a light beam from the fluorescent tube 41 to the liquid crystal panel unit 30 side, and from the fluorescent tube 41 to the opposite side of the liquid crystal panel unit 30. A reflection case 42 that reflects the emitted light beam and emits it toward the liquid crystal panel unit 30, a backlight substrate 43 that supplies power to the terminal portion of the fluorescent tube 41, and a back surface of the reflective case 42, is generated in the fluorescent tube 41. A heat radiating plate 44 is provided to release the heat to the outside through a front case 61 described later.
[0030]
The exterior case 60 includes a metal front case 61 and a transparent plastic back case 62. The front case 61 has an opening 61A for displaying an image formed by the liquid crystal panel unit 30. .
[0031]
As shown in FIG. 2, the display control board 50 is configured by mounting various circuit elements (circuit parts) on the board main body 51. The board main body 51 includes a display control circuit as shown in FIG. 52 and a panel application voltage control circuit 54 (voltage control circuit).
[0032]
The panel applied voltage control circuit 54 is a circuit that supplies an applied voltage to the liquid crystal panel unit 30 and includes various connectors and a connector 543 provided at an intermediate portion on the wiring pattern of the panel applied voltage control circuit 54. Consists of.
[0033]
(2) Configuration of Temperature Compensation Circuit Board As shown in FIG. 3, in the display device 11 described above, a depression is formed in a part of the outer peripheral edge of the diffusion plate 30b, and the temperature compensation circuit board 55 is formed in this depression. Is provided. Further, when the panel shield frame 30c is stacked from above the liquid crystal panel 30a, a guide projecting from the edge of the panel shield frame (display unit fixing frame) 30c toward the diffusion plate 30b side is provided with the liquid crystal panel 30a and the diffusion plate 30b. The size is set so as to cover from the side. For this reason, when the liquid crystal panel 30a and the panel shield frame 30c are attached to the diffuser plate 30b, the temperature compensation circuit board 55 protrudes between the liquid crystal panel 30a and the panel shield frame 30c in the direction including the display surface of the liquid crystal panel 30a. It will be arranged between the installed guides. In such a positional relationship, the temperature compensation circuit board 55 is disposed in the vicinity of the liquid crystal panel 30a and in a space continuous with the space in which the liquid crystal panel 30a exists, so that an actual temperature change of the liquid crystal panel 30a occurs. Temperature detection is possible in a close state.
[0034]
As shown in FIG. 4, the temperature compensation circuit board 55 includes a board body 551, a thermistor 552, a connector 553, and a copper pattern 554.
[0035]
The substrate body 551 is configured by printing a wiring pattern (not shown) on the surface of an insulating glass epoxy substrate, and a copper pattern 554 is provided on the back side.
[0036]
The thermistor 552 functions as a temperature compensation element and is electrically connected to the connector 553 by a wiring pattern on the substrate body 551. The copper pattern 554 is provided to change the heat capacity of the temperature compensation circuit board 55, and the temperature change characteristic of the thermistor 552 is adjusted to the temperature change characteristic of the liquid crystal panel 30a by adjusting the amount of the copper pattern 554. be able to.
[0037]
(3) Connection Structure of Display Control Board 50 and Temperature Compensation Circuit Board 55 The 4-pin connector 543 provided on the display control board 50 as described above and the 2-pin connector 553 of the temperature compensation circuit board 55 are shown in FIG. As shown in FIG. 2, they are connected by a two-core wire harness 56, and these constitute a connecting device.
[0038]
The wire harness 56 includes a 2-pin housing 561 connected to the connector 553 and a 4-pin housing 562 connected to the connector 543, and the 2-pin portion not connected to the connector 553 is short-circuited by a jumper J. .
[0039]
The panel application voltage control circuit 54 on the display control board 50 supplies an application voltage to the liquid crystal panel unit 30 via the jumper J, and this structure constitutes a connection failure detection means. The two-pin terminals of the connector 543 connected to the thermistor 552 are short-circuited by a fixed resistor 104b serving as a circuit element, and the fixed resistor 104b is connected in parallel to the thermistor 552.
[0040]
In such a connection structure, in a state where the connection between the connector 543 and the connector 553 is normally secured, the panel application voltage control circuit 54 can supply an application voltage to the liquid crystal panel unit 30 via the jumper J. it can.
[0041]
On the other hand, when the connection between the connector 543 on the display control board 50 side and the wire harness 56 is not normal, the applied voltage supply line from the panel applied voltage control circuit 54 to the liquid crystal panel unit 30 is divided at the jumper J portion. The applied voltage cannot be supplied to the liquid crystal panel unit 30. If the liquid crystal panel 30a is normally black, the display screen is black. If the liquid crystal panel 30a is normally white, the display screen is white and a connection failure between the wire harness 56 and the connector 543 is displayed. .
[0042]
(4) Effects of the First Embodiment According to the first embodiment as described above, there are the following effects.
[0043]
That is, since the display device 11 includes the connection failure detection means, when a failure in electrical continuity of the connection device is detected, the display on the liquid crystal panel 30a becomes white or black. Defects can be confirmed immediately. Therefore, the applied voltage control by the thermistor 552 can be reliably performed by confirming the connection failure before being stored in the exterior case 60.
[0044]
Further, since a structure for detecting a connection failure is provided on the applied voltage supply line for supplying the applied voltage to the liquid crystal panel unit 30 from the panel applied voltage control circuit 54, the display of the liquid crystal panel 30a can be performed by a simple method of cutting off the applied voltage. Can be considered defective.
[0045]
Furthermore, since the jumper J is provided in the wire harness 56 and the applied voltage supply line is set via the jumper J, a connection failure between the connector 543 of the display control board 50 and the wire harness 56 can be detected immediately. it can. Since the 2-pin connector 553 is used on the temperature compensation circuit board 55 side, the temperature compensation circuit board 55 is not increased more than necessary, and the temperature compensation circuit board 55 can be arranged in a narrow space. it can.
[0046]
Further, by configuring the connection failure detection means as described above, it is possible to reliably detect connection failure with an extremely simple structure.
[0047]
(5) Configuration and Effect of Second Embodiment Next, the second embodiment of the present invention will be described. In the following description, parts that are the same as the parts or members already described are denoted by the same reference numerals, and the description thereof is omitted or simplified.
[0048]
The connection failure detection means according to the first embodiment uses a connector 543 on the display control board 50 side as a 4-pin connector, a connector 553 on the temperature compensation circuit board 55 side as a 2-pin connector, and is connected to both connectors 543 and 553. The jumper J is provided in the wire harness 56, and the applied voltage supply line is configured to pass through the jumper J.
[0049]
On the other hand, as shown in FIG. 6, the connection failure detection means according to the second embodiment uses a 4-pin connector as the connector 753 on the temperature compensation circuit board 55 side, and the wire harness 76 connected to both the connectors 543 and 753. The difference is that a jumper J for short-circuiting between the two pin terminals of the four pins of the connector 753 is provided on the connector 753 portion on the temperature compensation circuit board 55 side.
[0050]
That is, the applied voltage supply line from the panel applied voltage control circuit 54 to the liquid crystal panel unit 30 flows to the temperature compensation circuit board 55 via the wire harness 76 and returns to the display control board 50 again via the jumper J. It is configured.
[0051]
According to the connection failure means according to the second embodiment, in addition to the effects described in the first embodiment, there are the following effects.
[0052]
That is, since the jumper J is provided in the connector 753 portion on the temperature compensation circuit board 55 side and the applied voltage supply line passes through this jumper, the connection between the wire harness 76 and one of the connector 543 and the connector 753 Even in the case of disconnection, the supply of the applied voltage is cut off and the connection failure can be confirmed immediately.
[0053]
(6) Configuration and Effect of Third Embodiment Next, the third embodiment of the present invention will be described.
[0054]
In each of the embodiments described above, a jumper J is provided in the wire harness 56 or the connector 543 that constitutes the connection device for the display control board 50 and the temperature compensation circuit board 55, and the connection failure is caused by passing the applied voltage supply line through the jumper J. The detection means was constituted.
[0055]
On the other hand, the third embodiment is different in that a fixed resistor 104b, which is a circuit element connected in parallel to the thermistor 552, is mounted on the temperature compensation circuit board 55 as shown in FIG. To do.
[0056]
That is, when the wire harness 86 is poorly connected at the connector 553 portion on the temperature compensation circuit board 55 side or the connector 843 portion of the display control board 50, the panel applied voltage control circuit 54 including the connector 843 is The voltage applied to the display unit is controlled by detecting a change in the terminal voltage during the signal line that reaches the temperature compensation circuit board 55.
[0057]
According to the third embodiment, by detecting the change in the terminal voltage by the panel applied voltage control circuit 54, it is possible to detect a failure in the electrical continuity of the connection device, thereby causing the display on the liquid crystal panel 30a to be defective. A signal to the effect can be output, and the same effect as in the first embodiment can be enjoyed.
[0058]
(7) Modifications of Embodiments The present invention is not limited to the above-described embodiments, and includes modifications as described below.
[0059]
In each of the embodiments described above, the connection failure detection means controls the voltage applied to the liquid crystal panel unit 30 to display that the liquid crystal panel unit 30 is defective. However, the present invention is not limited to this. That is, connection failure detection means may be provided on a power supply line (inverter circuit) to the backlight provided on the display control board.
[0060]
In each embodiment, the wire harness 56 is connected to the 2-pin or 4-pin housing 561 connected to the connectors 553 and 753 on the temperature compensation circuit board 55 side and the connectors 543 and 843 on the display control board 50 side. However, the present invention is not limited to this. That is, a so-called flat cable (FFC) of a type that is directly connected to the connectors 553, 753, 543, and 843 without using the housings 561 and 562 can be used as the wire harness. In this case, the 2-pin portion can also be short-circuited by a jumper provided on the flat cable, thereby constituting a connection failure detecting means.
[0061]
Further, in the second embodiment of the present invention, the jumper J is provided on the temperature compensation circuit board 55 so as to short-circuit between the two pin terminals of the connector 753. However, the present invention is not limited to this. You may comprise so that between 2 pin terminals of the connector 753 may be short-circuited by the wiring pattern formed on the compensation circuit board 55. FIG.
[0062]
In the embodiment, the liquid crystal panel 30a is a panel using TFD as a switching element. However, the present invention is not limited to this, and other active matrix liquid crystal panels such as TFT and simple matrix liquid crystal panels such as STN are used. The present invention may be used.
[0063]
In addition, the specific structure, shape, and the like when implementing the present invention may be other structures as long as the object of the present invention can be achieved.
[0064]
【The invention's effect】
According to the display device according to the present invention as described above, since the connection failure detecting means for detecting the connection failure of the connection device for connecting the temperature compensation circuit board and the display control board is provided, the electrical continuity of the connection device is provided. When the defect is detected, the display on the display unit becomes defective and the electrical continuity of the connection device can be confirmed immediately, and the panel applied voltage control by the temperature compensation element can be reliably performed.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a structure of a display device according to an embodiment of the present invention.
FIG. 2 is a perspective view illustrating a structure of a display control board in the embodiment.
FIG. 3 is an enlarged view of a liquid crystal panel unit portion shown in FIG.
FIG. 4 is a schematic perspective view showing the structure of a temperature compensation circuit board.
FIG. 5 is a schematic diagram showing a connection structure between a display control board and a temperature compensation circuit board.
FIG. 6 is a schematic diagram showing a connection structure between a display control board and a temperature compensation circuit board of a display device according to a second embodiment of the invention.
FIG. 7 is a schematic diagram showing a connection structure between a display control board and a temperature compensation circuit board of a display device according to a third embodiment of the invention.
FIG. 8 is a block diagram showing a configuration of a conventional temperature compensation control system.
FIG. 9 is a connection diagram between the display control board and the temperature compensation circuit board shown in FIG. 8;
[Explanation of symbols]
11 Display Device 30 Liquid Crystal Panel Unit 30a Liquid Crystal Panel (Display Unit)
41 Fluorescent tube (light source)
50 Display control board 54 Panel applied voltage control circuit (voltage control circuit)
55 Temperature Compensation Circuit Board 56, 76, 86 Wire Harness 104b Fixed Resistance (Circuit Element)
543, 553, 753, 843 Connector 552 Thermistor (temperature compensation element)
J Jumper

Claims (5)

A liquid crystal panel that forms an optical image by modulating a light beam emitted from a light source, a temperature compensation circuit board on which a temperature compensation element that detects a temperature in the vicinity of the liquid crystal panel is mounted, and a detection signal of the temperature compensation element A display device comprising a display control board including a voltage control circuit for controlling a voltage applied to the liquid crystal panel in response, and a connection device for electrically connecting the temperature compensation circuit board and the display control board,
When detecting an electrical continuity failure of the connection device, the device includes a connection failure detection means for outputting a signal indicating that the display of the liquid crystal panel is defective,
The connection device includes a pair of connectors provided on each of the display control board and the temperature compensation circuit board, and a wire harness attached to each connector,
The connection failure detection means is provided in the middle of the applied voltage supply line to the liquid crystal panel or in the middle of the power supply line to the light source, and the applied voltage supply line or the power supply line is connected to the pair of connectors. A display device characterized by being configured to pass through at least one of them. The display device according to claim 1,
The connector provided on the display control board is composed of a 4-pin connector having four signal input / output terminals, and the connector provided on the temperature compensation circuit board is a two-pin connector having two signal input / output terminals. Configured,
The wire harness includes a signal wire that electrically connects the two terminals of the 2-pin connector and the two terminals of the 4-pin connector, and a jumper that short-circuits the remaining two terminals of the 4-pin connector,
The display device characterized in that the applied voltage supply line or the power supply line passes through the jumper. The display device according to claim 1,
The connector includes a 4-pin connector having four signal input / output terminals, and the wire harness includes four signal lines for connecting the signal input / output terminals of each connector,
Two of the four signal lines connect the temperature compensation element and the voltage control circuit, and the other two signal lines are short-circuited on the temperature compensation circuit board side,
The display device, wherein the applied voltage supply line or the power supply line passes through the other two signal lines. The display device according to claim 3,
The other two signal lines are short-circuited at a connector portion of the temperature compensation circuit board. The display device according to claim 3,
The other two signal lines are short-circuited by a wiring pattern formed on the temperature compensation circuit board.

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