JPH1187774A - Led display device and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a LED display device which can specify light emission diode which does not light or emits undesirable light with relatively simple circuitry and also which can display in full colors and can be easily large-sized by providing a monitor means for monitoring an abnormal signal from a common output line synchronously with driving of each light emitting diode. SOLUTION: First, a MPU comprising an arithmetic device shared with a communication means is driven by a test mode to control light-up of a light emitting diode, and also abnormality of the light emitting diode lit up synchronously with it is sensed. Abnormality sensing means 1,2 are constituted to be connected synchronously with a light-up output terminal. Signals from the abnormality sensing means 1, 2 are temporarily stored in a memory means comprising a RAM or the like. At this time whether the light emitting diode such as the MPU has been driven or whether abnormality of the abnormality sensing means 1, 2 or the like has been sensed can be stored. Thus the number of the abnormality sensing means can be reduced, while circuitry can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention arranges an LED (hereinafter, also referred to as a light emitting diode), which is a kind of functional element, in a dot matrix in which a plurality of rows and columns are arranged vertically and can display various data such as characters and figures. The present invention relates to an LED display device and the like, and in particular, can identify a light emitting diode having an abnormality (non-lighting, undesired light emission, etc.) from a plurality of light emitting diodes with a relatively simple configuration.

[0002]

2. Description of the Related Art At present, light emitting diodes capable of emitting ultra-high brightness of RGB (red, green, blue) each exceeding 1000 mcd have been developed. Accordingly, a full-color LED display device in which various characters, image information, and the like can be visually recognized by a large number of people has been made possible by arranging light emitting diodes capable of emitting RGB light in a dot matrix and lighting them as desired. As LED display devices have become larger and full color, there has been an increasing demand from society for display devices capable of displaying higher quality.

An example of a full-color display device is RGB.
Are combined into one picture element. Each of the picture elements is arranged in a 16 × 16 dot matrix to form a part of a display image. Each light emitting diode is covered with an epoxy resin or the like, and has an LED chip serving as a semiconductor element therein.
The LED chip is electrically connected to each electrode of the LED chip and a lead frame or the like using gold wire, solder, Ag paste, or the like. Similarly,
The lead frame of each light emitting diode is connected to the substrate by soldering or the like. Further, it is also electrically connected to a substrate on which a driving unit for turning on / off each light emitting diode is configured.

[0004] The driving means calculates the lighting time of each light emitting diode based on the input data, and drives each light emitting diode. An LED module can be formed by a substrate on which light emitting diodes are arranged in a dot matrix and a substrate having driving means electrically connected thereto. LE
Each D module is electrically connected to two or more D modules, and also connected to a control device that controls each LED module. Image data, character data, and the like are sequentially and continuously transmitted from the control device to the LED module. Each of the LED modules is, for example, 16 × 10 and integrated to constitute an LED display as a whole. Various data can be displayed by sending display data to such an LED display.

[0005] The number of light emitting diodes constituting such an LED display is extremely large. In addition, it is used in various environments such as outdoors where temperature and humidity cycles are severe. Therefore, the electrical connection inside and outside the light emitting diode is short-circuited (leakage due to electrical contact with dust, etc.) or opened (disconnection, insufficient contact, etc.) during formation or use of the LED display, and further, the semiconductor element itself is damaged. There are cases. In this case, the light emitting diode may be partially turned off or the light emission luminance may be significantly reduced. Missing image on LED display (partially unlit LED
) And image unevenness (the presence of partially low-brightness LEDs) are noticeable and unfavorable in image quality. Defective portions of the light emitting diodes can be relatively easily found by lighting each light emitting diode.

[0006]

However, driving all the light emitting diodes and checking the light emitting state with the naked eye is an extremely complicated operation. Further, after the large display is installed on a billboard or the like, there is a problem that an abnormal portion cannot be detected accurately.

[0007] Next, a method of providing a current detection circuit for confirming the operation of the light emitting diode and specifying an abnormal point can be considered. The data from each current detection circuit is sent to an arithmetic circuit to determine which light emitting diode has an operation failure. Thus, in an LED display device having a certain number of light emitting diodes, an abnormal portion can be specified.

However, data from each current detection circuit for confirming the operation of the light emitting diode is provided for each light emitting diode, and in order to monitor the data, each data detection circuit must be connected to the monitoring means in a one-to-one correspondence. . In an LED display or an LED unit, the number of light emitting diodes used is extremely large, and the circuit constituting the abnormality detecting means is complicated, large, and impractical. Therefore, it is difficult to achieve both simplification of the circuit constituting the abnormality detection means and enlargement of the LED display. That is, there is a drawback that the connection becomes extremely large and the circuit configuration becomes complicated as full color or multi color and the LED display becomes larger.

In particular, the number of light emitting diodes used in an LED display is, for example, 16 × 16 dot matrices arranged in 10 rows and 16 columns, 16 × 16 × 3 colors × 10x
16 may be 122 or 880 or more. Therefore, in a full-color and larger-sized LED display, the abnormality detection of the above configuration is not sufficient, and a further excellent LED display device is required. The present invention has been made in view of the above points, and provides an LED display device that can specify a non-lighted or undesired light emitting diode with a relatively simple circuit configuration, and that can be easily made full-color or large. It is intended to be.

[0010]

SUMMARY OF THE INVENTION The present invention is an LED display device having a plurality of light emitting diodes arranged in a dot matrix and driving means capable of emitting light from each of the light emitting diodes independently. In particular, abnormality detection means for detecting an abnormality of each light emitting diode and outputting an abnormality signal, a common output line for connecting a plurality of abnormality detection means in parallel to output an abnormality signal in common, and a common output line connected to the common output line An LED display device having monitoring means for monitoring an abnormal signal from a common output line in synchronization with driving of a diode.

With the configuration of the present invention, the connection from each abnormality detecting means to the monitoring means can be extremely simplified. Even if the size of the LED display device is increased and the number of light emitting diodes is increased, the data input to the monitoring means for monitoring the abnormality can be reduced to one. Therefore, the circuit configuration can be simplified without connecting each of the plurality of abnormality detection units to the monitoring unit in a one-to-one correspondence, and an LED display device compatible with a large size and full color can be provided. Further, by synchronizing the abnormality detection with the lighting of the light emitting diode, it is possible to easily specify the light emitting diode or the like in which the abnormality has occurred.

In the LED display device according to a second aspect of the present invention, the abnormality detecting means is constituted by an open collector type circuit, and outputs from the abnormality detecting means are wired-OR connected to a common output line to monitor the abnormality. Is input to This makes it possible to provide a circuit that can be simplified even if the LED display device capable of displaying various image data and the like is made larger.

The LED display device according to the third aspect of the present invention detects an open and / or short circuit of the current flowing to the light emitting diode as an abnormality. Thereby, the failure mode of the light emitting diode can be specified.

According to a fourth aspect of the present invention, in the LED display device, the abnormality detecting means has at least one reference voltage at an output of a collector or the like of a transistor constituting driving means for lighting each light emitting diode. Circuit. Thus, an LED display device having a simpler configuration can be obtained.

In the LED display device according to the fifth aspect of the present invention, the abnormality detecting means includes a control current detecting circuit in a transistor constituting driving means for lighting each light emitting diode. An LED display device having a simpler configuration can be obtained.

A semiconductor device according to a sixth aspect of the present invention comprises:
A semiconductor device having a driving unit capable of independently driving a plurality of functional elements, and an abnormality detecting unit capable of individually detecting an abnormality of the functional element corresponding to the driving unit. In particular, the final output circuit of the abnormality detecting means is constituted by an open collector type circuit, and outputs from each abnormality detecting means are OR-connected. As a result, it is possible to detect abnormalities of a plurality of functional elements with a relatively simple device.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The inventor of the present invention
It has been found that by sharing the output from the abnormality detecting means for detecting the abnormality of each light emitting diode and synchronizing with the driving of each light emitting diode, it is possible to identify the abnormal location of each light emitting diode with a relatively simple configuration, and form the present invention. Reached.

That is, instead of connecting a plurality of wirings from a plurality of abnormality detecting means for detecting abnormality of the light emitting diode to a plurality of monitoring means for monitoring the abnormality, a common output line connected in parallel with the plurality of abnormality detecting means is used. Connect to monitoring means. As a result, the circuit configuration can be extremely simplified even if the number of abnormality detection means increases. Further, by detecting an abnormality at the time of driving a specified light emitting diode in synchronization with the driving, it is possible to specify an abnormal part.

FIG. 5 shows an example of the present invention. The semiconductor device is electrically connected to light-emitting diodes arranged in a dot matrix that can be dynamically driven. The semiconductor device is provided with abnormality detecting means 501 in one-to-one correspondence with the segment driver 504 constituting driving means by driving transistors. The abnormality detecting means 501 includes a circuit for detecting an open circuit and a circuit for detecting a short circuit. The semiconductor device has a configuration in which each abnormality detection unit 501 is connected to the open detection output 504 by an OR circuit. Similarly, each of the abnormality detecting means 501 is connected to the short-circuit detection output 505 by an OR circuit.

Here, if the operating state of the light emitting diode 201 does not light up as desired due to damage to the internal circuit or the LED chip itself, the abnormality detecting means 501 detects this and outputs an abnormal signal. Open detection output of semiconductor device 5
04 and the short circuit detection output 505 can be connected to a common output line (not shown) for each light emitting diode of each emission color. Therefore, each abnormality detecting means 501 is wired OR-connected to the common output line, and if there is an abnormality in any one of the light emitting diodes 201, it can be detected by the monitoring means monitoring the abnormality. By monitoring the monitoring means (not shown) when the specific light emitting diode 201 is turned on, it is possible to detect which LED module of the LED display has an abnormality. Similarly, it is possible to detect which light emitting diode of the LED module has an abnormality. The abnormality detecting means for detecting each light emitting diode 201 is all electrically connected by the monitoring means by a common output line. Therefore, the monitoring means can detect abnormality of all the light emitting diodes 201 by at least one common output line. In addition, by synchronizing with the lighting of the light emitting diode, it is possible to easily determine which location of the light emitting diode has an abnormality. Further, it is possible to detect what kind of failure has occurred based on the output from the abnormality detecting means. Hereinafter, each configuration of the present invention will be described in detail.

(Abnormality detecting means 501) Abnormality detecting means 50
1 indicates that an abnormality such as lighting / non-lighting of each light emitting diode 201 and a decrease in luminance can be detected. Specifically, by checking the light emission of each light emitting diode 201 and the current and voltage flowing through a transistor and the like that constitute driving means connected to each light emitting diode 201, it is possible to check for an open or a short circuit. In addition, the case of short-circuiting to the ground side and the case of short-circuiting to the power supply side can be checked.
Further, the light emission of the light emitting diode 201 can be directly detected by a solar cell or an optical sensor. In any case, the light emitting diode 2 that cannot obtain the desired light emission
01 can detect an abnormality and output an abnormality signal.

The abnormality detecting means 501 includes the light emitting diode 2
It can be formed integrally with an IC constituting a driving means for lighting 01. Specifically, a voltage comparison circuit having a reference voltage is formed as a voltage detection circuit 301 between the collector of the transistor constituting the driving means and the LED 201 as shown in FIG. 3, or a transistor constituting the driving means as shown in FIG. By configuring a control current detection circuit as the current detection circuit 401 on the base of the above, an IC integrated with the driving means can be configured. When one of the voltage detection circuit 301 and the current detection circuit 401 serving as the abnormality detection means detects an abnormality, the output is changed from the H level to the L level.
Level. That is, the voltage detection circuit 301
And each light emitting diode 2 connected to the current detection circuit 401
If any one of 01 is abnormal, the output can be set to L level and the abnormality can be determined by the monitoring means via the common output line 302.

Further, it is not necessary to provide the abnormality detecting means one-to-one with the light emitting diodes, and at least one abnormality detecting means corresponding to, for example, RGB light emitting diodes can be provided in an IC constituting the driving means. . In this case, the abnormality detection means and each light emitting diode may be individually switched in synchronization with the detection operation to be detected. This makes it possible to reduce the number of abnormality detection means and configure the abnormality detection means with a relatively simple configuration. FIG. 7 shows an example in which one abnormality detection unit is provided for the R light emitting diodes arranged in a dot matrix.

(Monitoring means 106) The monitoring means 106
Abnormality detecting means 50 provided in each light emitting diode 201
1 monitors an abnormal signal from the common output line 101 connected in parallel. If there is an abnormality in the light emitting diode, an abnormality signal is sent from each abnormality detecting unit 501 to the monitoring unit 106. For example, when the output OUT of the open collector type IC constituting the abnormality detecting means 501 changes from the H level to the L level, the monitoring means 106 can determine that an abnormality has occurred. Further, by detecting an abnormality in synchronization with the driving of the specific light emitting diode 201, the monitoring means 106 can grasp which light emitting diode or LED module is being driven. The monitoring means 106
Since it can be centrally managed via the common output line 101, it can be provided in the control means 105 for controlling a plurality of LED modules.
It can also be provided for each ED module.

Dynamically driven light emitting diode 201
Is a segment driver 2 for each LED module
The intersection point of the common driver 203 and 04 is lit. If the monitoring means 106 receives an abnormal signal while transmitting the data for lighting the intersection, the abnormal light emitting diode 201 can be identified.

The light emitting diode 201 and the LED module 103 in which the abnormality has been specified are stored in a storage means such as a RAM provided commonly to the LED display or provided for each LED module, and are checked when desired. The abnormal location can be grasped by using. Also,
Provided in common with the LED display or each L
An abnormality such as a light emitting diode can be transferred to a device that manages the LED display device 101 by a wired or wireless communication unit connected to a storage unit provided for each ED module. In this case, it is possible to notify not only an abnormality but also an abnormal location. Further, depending on the abnormality detecting means 501, an abnormal mode of short circuit or open can be notified. In addition, when abnormal data enters the monitoring means, the display data can be automatically interrupted and the display content can be changed. The abnormality detection step may be performed when the LED display device 101 is started, or may be performed periodically by providing a timer. Further, an abnormality can be detected by arbitrarily flowing a test pattern.

(Common output lines 101 and 302) The common output lines 101 and 302 are connected in parallel with the abnormality detecting means 501 for detecting abnormality of each light emitting diode 201, and transmit abnormality data from the abnormality detecting means 501 to the monitoring means 106. Is what you do. Therefore, a plurality of light emitting diodes 201
If there is an abnormality somewhere, an abnormal signal will be transferred to the monitoring means 106 via the common output lines 101 and 302. The common output lines 101 and 302 may be configured as a single line, or may be divided for each of the RGB emission colors. Further, it may be divided into an open detection output 504 for detecting an open circuit and a short circuit detection output 505 for detecting a short circuit. In this manner, a plurality of common output lines 101 and 302 can be provided according to desired characteristics. In any case, it is better that the number of the common output lines 101 and 302 output from each abnormality detecting means 501 is small.

(Functional element) The functional element is an element that performs various functions by supplying electric power, such as a light emitting element, a piezoelectric element, a light receiving element, a heating element used for an ink jet, a liquid crystal device, and the like. In particular, in the present invention, such a functional element is used in an apparatus using two or more such functional elements such as a dot matrix. By using the semiconductor device of the present invention, it is possible to determine which of the plurality of functional elements has an abnormality with a relatively simple circuit configuration.

Light emitting diode 20 which is one of the functional elements
Reference numeral 1 denotes a unit which can be sequentially driven by the driving unit based on a signal from the control unit 105. Therefore, it is possible to use a semiconductor light emitting element that can emit various lights. As semiconductor elements used for light emitting diodes, GaP, G
aAs, GaN, InN, AlN, GaAsP, GaAs
lAs, InGaN, AlGaN, AlGaInP, I
An example in which a semiconductor such as nGaAlN is used for a light emitting layer is given. Further, the structure of the semiconductor may be a homostructure having a MIS junction, a PIN junction or a pn junction, a heterostructure, or a double heterostructure.

The emission wavelength can be variously selected from ultraviolet light to infrared light depending on the material of the semiconductor layer and the degree of mixed crystal thereof.
Further, a single quantum well structure or a multiple quantum well structure in which a light emitting layer is thin to provide a quantum effect can be used. In addition, a light emitting diode capable of emitting white light by a complementary color of light from the LED chip and a fluorescent substance excited and emitted by the LED chip can be used as well as the three primary colors of RGB. The light emitting diode can have a structure in which an LED chip as a light emitting element is electrically connected to a lead frame and covered with a mold resin. A light emitting diode such as a shell type or a chip type LED can be formed depending on the shape of the coating.

(Driving Means) The driving means is capable of driving only the desired light emitting diode 201 by supplying electric power to the light emitting diode 201 or the like which is a functional element. Such a driving unit can be constituted by a common driver 503 and a segment driver 504 in the case of the light emitting diodes 201 arranged in a dot matrix to be dynamically driven. By switching the common driver and the segment driver, a desired functional element can function. Hereinafter, specific examples of the present invention will be described in detail, but it goes without saying that the present invention is not limited to only these examples.

[0032]

【Example】

(Example 1) A bullet-shaped light emitting diode 201 capable of emitting light for each of RGB was used. Each light emitting diode is
A light emitting diode using indium gallium nitride, which is a nitride semiconductor capable of emitting blue light, and an indium capable of emitting green light, which has a greater In composition than indium gallium nitride capable of emitting blue light A light emitting diode using gallium nitride and a light emitting diode using an indium gallium aluminum arsenide semiconductor element capable of emitting red light. Such a light emitting diode is configured as one picture element using RGB. For the light emitting diodes arranged on the substrate, one picture element is arranged in a 16 × 16 dot matrix by an automatic mounting machine. The copper foil pattern provided on the substrate and the lead frame are soldered by an automatic soldering device. The LED module 103 is formed by electrically connecting the substrate on which the light emitting diodes are formed to driving means. The 16 × 9 LED modules 103 are arranged directly or indirectly distributed by the distribution board 104 or the like.
05 to form the LED display device 100.

Data such as image information is transferred to an L by an interface board which is a control means connected to a computer.
Convert for ED display. Converted data 10
2 is sequentially input from the control means 105 to the drive means of each LED display. The driving unit that drives each light emitting diode 201 turns on the light emitting diode at a constant cycle for each frame constituting one screen based on the display data input from the control unit and turns off the light based on the display data. The control unit drives the common driver 203 and the segment driver 204 to perform dynamic driving, so that the light emitting diode 2
01 can be sequentially turned on and off.

In the IC constituting the driving means of the present invention, a voltage comparison circuit 301 having a reference voltage at the collector output of each driving transistor is added in addition to the driving transistors for controlling on / off of each light emitting diode. . The voltage comparison circuit 301 functions as abnormality detection means 501 for detecting abnormality of each light emitting diode 201. By comparing the reference voltage of the voltage comparison circuit 301 with the voltage applied to the light emitting diode 201, it is possible to determine whether the light emitting diode is short-circuited or open. When the reference voltage of the voltage comparison circuit 301 matches a certain comparison value of the light emitting diode 201, it is determined that there is an abnormality, and an abnormality signal is output.

The output of the voltage comparison circuit is of an open collector type. The outputs of the voltage comparison circuits provided corresponding to the respective light emitting diodes are directly connected in parallel and the reference voltage Vc
A resistor is connected between c and the output OUT. When there is an abnormality in the light emitting diode, one of the output transistors is turned on by an output from the voltage comparison circuit which is an abnormality detecting means. Common output line 10 connected to each abnormality detecting means 501
At 1 and 302, when at least one of the output transistors is turned on, the output OUT goes low. The monitoring unit 106 that monitors the voltage of the common output line determines that an abnormality has occurred due to the change of the common output line from the H level to the L level. The abnormal signal output to the common output line is controlled by the control means 10 which monitors the presence or absence of the abnormal signal through one line.
5 is input to the monitoring means 106.

In this state, the plurality of light emitting diodes 20
It is determined that any one of the two has an abnormality. LED
To determine which of the light emitting diodes of the display device 101 has an abnormality, the light emitting diodes are sequentially turned on for each of the RGB of the LED display device. A blue light emitting diode sequentially drives a common driver and a segment driver arranged in a dot matrix. If there is an abnormality in synchronization with the lighting, an abnormality signal is output from the abnormality detecting means to the monitoring means. The lighting location at the time when abnormal data is detected is specified. Thereby, the location of the light emitting diode in which the abnormality has occurred can be specified from the LED display device. An abnormality is sequentially detected for other colors and each LED module 103.

The abnormal location of the light emitting diode specified in this way is stored in a memory. By examining the memory to identify the abnormal light emitting diode and replacing only the identified abnormal light emitting diode, it is possible to obtain an LED display device with an excellent display state at all times.

(Example 2) As shown in FIG. 6, an abnormality detection example in which one LED unit is used as the LED display device instead of configuring the LED display device with the entire LED display as in Example 1 is shown. As LED units, light-emitting diodes capable of emitting light by RGB are arranged in a 16 × 16 dot matrix. An abnormality detecting means for detecting an abnormality of each light emitting diode and a common output line for outputting an abnormality are provided inside the LED unit. Also, LE
The D unit is provided with communication control means and storage means connected to the common output line. An LED display is configured by combining a plurality of such LED units.

The operation at the time of an abnormality detection test in such an LED display will be described. First, in the test mode, the MPU, which is an arithmetic unit shared with the communication means, is driven to control the lighting of the light emitting diode and detect an abnormality of the light emitting diode which is turned on in synchronization with the control. The abnormality detecting means is configured to be connected in synchronization with the lighting output terminal. The signal from the abnormality detection unit is temporarily stored in a storage unit such as a RAM. At this time, which light emitting diode the MPU was driving,
Which abnormality is detected by the abnormality detecting means can be stored. Thus, the number of abnormality detection means can be reduced, and the circuit configuration can be further simplified. Further, by transmitting abnormal data stored outside the LED display via a communication line or the like from the communication means, it is possible to grasp an abnormal location, an abnormal situation, and the like outside the LED display.

[0040]

According to the structure of the present invention, even in a semiconductor device using a large size or an extremely large number of functional elements, an abnormal semiconductor device can be detected with a relatively simple structure.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a configuration of an LED display device used in the present invention.

FIG. 2 is a schematic explanatory view of an LED module used in the LED display device of the present invention.

FIG. 3 is a circuit diagram showing one configuration example in a semiconductor device of the present invention.

FIG. 4 is another circuit diagram showing one configuration example in the semiconductor device of the present invention.

FIG. 5 is a schematic explanatory view showing a configuration inside a semiconductor device of the present invention.

FIG. 6 is a schematic explanatory view showing a configuration of another LED display device of the present invention.

FIG. 7 is a schematic explanatory view showing the connection of another abnormality detecting means of the present invention.

[Explanation of symbols]

 100 LED display devices 101, 302 Common output line 102 Display data 103 LED module 104 Distribution board 105 Control device 106 Monitoring means 200 LED module 201: Light emitting diode 202: Signal processing circuit 203, 503: Common driver 204, 504: Segment driver 301: Voltage detection circuit 401: Current detection circuit 501: Abnormal Detection means 504: Open detection output 505: Short detection output

Claims (6)

[Claims] 1. An LED display device comprising: a plurality of light emitting diodes arranged in a dot matrix; and a driving unit capable of emitting light from each of the light emitting diodes independently. An abnormality detection unit that outputs a signal, a plurality of abnormality detection units that are connected in parallel to output a common abnormality signal, and a common output line that is connected to the common output line and synchronizes with the driving of each of the light emitting diodes. An LED display device having monitoring means for monitoring an abnormal signal from an output line. 2. The LED according to claim 1, wherein said abnormality detecting means is constituted by an open collector type circuit, and an output from each abnormality detecting means is wired-OR-connected to a common output line and inputted to the monitoring means. Display device. 3. The LED display device according to claim 1, wherein the abnormality is an opening and / or a short circuit of a current flowing to the light emitting diode. 4. The L according to claim 1, wherein said abnormality detecting means comprises a voltage comparing circuit having at least one or more reference voltages at an output of a driving means for lighting each light emitting diode.
ED display device. 5. The LED display device according to claim 1, wherein said abnormality detecting means includes a control current detecting circuit in a driving means for lighting each light emitting diode. 6. A semiconductor device comprising: driving means capable of independently driving a plurality of functional elements; and abnormality detecting means capable of individually detecting abnormalities of the functional elements corresponding to the driving means, A semiconductor device, wherein a final output circuit of the abnormality detecting means is constituted by a plurality of open collector type circuits and circuits, and outputs from each abnormality detecting means are OR-connected.