JP2995664B2 - Information display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information display device in which light emitting diodes are configured as display dots, and the display dots are arranged vertically and horizontally in a matrix and displayed in dot spelling. .

2. Description of the Related Art Conventionally, there are traffic information boards, road information boards, and the like as information display devices in which display dots are arranged vertically and horizontally on a matrix, and display dots are displayed and dot-spelled. Light emitting diodes are used for the display elements of these display panels because they can display multicolors such as red and yellow-green.

In addition, since these information boards are placed outdoors where environmental conditions are poor, the display state may be disturbed due to failure of parts due to temperature rise due to irradiation of sunlight, vibration due to road traffic, etc., or poor contact of connectors. There is. On the other hand, on a road information board, information such as cliff breaks is displayed, and important displays such as stopping a passing vehicle are performed. Therefore, such a display disturbance is a serious problem.
Therefore, conventionally, the current flowing through each of the light emitting diodes constituting the display dots on the display surface is detected, and the detected data is compared with the display data for designating the display content to detect a disturbance in the display state. When an abnormality occurs, an alarm is output.

A specific example of such a conventional information display device will be described with reference to FIGS.

FIG. 8 shows a part of the display surface constituted by each display dot, and this part is shown in an extracted form. D1
Reference numerals D64 to D64 denote light-emitting diodes, and the hatched portions indicate that the light-emitting diodes emit light and are displayed. In this example, katakana "a" is displayed. FIG. 7 is a circuit diagram showing these displays. In FIG. 7, D1 to D64 are light-emitting diodes constituting the display surface of FIG. 8, and a control circuit for driving each of these light-emitting diodes and a circuit for detecting a current flowing through the light-emitting diodes are surrounded by a chain line. In the circuit A, the configuration of the control circuit A is all the same. In the control circuit A, M stores display data for displaying display dots in a storage circuit. This stored data is
The data is transferred from the storage circuit MEM1 through the terminal D and stored. The output of the storage circuit M is the input of the AND circuit AND, and the other input of the AND circuit AND is connected to the output terminal CP of the pulse generator PG through the terminal P.

The pulse generator PG is a photoelectric converter such as a photoelectric automatic blinker
In response to the LE signal, the state "1" is output to the terminal CP in the daytime as shown in FIG. 9 (a), and in the nighttime, the state "1" is shown in FIG. 9 (b).
As shown in the figure, a pulse signal that periodically outputs a “1” state at time t1 and outputs a “0” state at time t2 is generated. Therefore, if there is display data, the output of the AND circuit AND is in a state similar to the state shown in FIG. 9, and when in the "1" state, that is, when it is at the "1" level, it becomes the base current of the transistor Tr1, and Turn Tr1 on. Also, the light emitting diode D1
A constant current element FI such as a resistor or a constant current diode or a constant current circuit is connected to the anode of
Power is supplied via. And the transistor Tr1
Is turned on, a current flows through the light emitting diode D1, and this becomes the base current of the transistor Tr2 via the cathode. As a result, the power supply E from the emitter of the transistor Tr2 via the collector and the emitter of the transistor Tr1
Flows to When the base current flows, the transistor Tr2 is turned on and the input of the inverter INV is set to “0”, so that the output becomes “1” and is output from the terminal O.
Stored in MEM2.

On the other hand, a coincidence detector C is connected to the memory circuits MEM1 and MEM2. The coincidence detector C compares the data of both memory circuits, and outputs a signal to the AR terminal if they do not coincide,
I am trying to issue an alarm. Where the pulse generator PG
The reason that the output of the AND circuit AND is output only for the time t1 at night is that the current flowing through the light emitting diode is made short so that it does not cause halation due to darkening, Times t1 and t2 are selected so that the operation is repeatedly performed at a high speed so that even if the light emitting diode is turned off, the eye can continuously see from the afterimage phenomenon.

[Problem to be Solved by the Invention] In FIG. 7, the circuit for monitoring
Each display dot requires components of the transistor Tr2, the inverter INV, and the storage circuit MEM, and also requires the terminal O. Therefore, as the number of display dots increases, the number of components increases as the number of display dots increases.

For example, if display dots are arranged at a pitch of 10 mm on a display surface of 2m x 4m, the number of display dots will be 200 x 400 = 80,000 dots, and the number of parts for monitoring and the number of terminals will be the product of them. Therefore, there was a problem that the price became high.

Furthermore, from the viewpoint of the reliability of the information display device, the large number of components required for monitoring results in a high failure rate and a high failure rate of the monitoring circuit provided for monitoring the disconnection of the light emitting diode. As a result, there is a problem that reliability is reduced. Further, a memory circuit M, an AND circuit AND, a transistor Tr1, a constant current element, and the like, which are circuits for display, are commercially available as an integrated IC. For example, TD62
According to the C850N, one IC can drive 16 display dots with a constant current, which is advantageous in terms of size reduction and cost. However, as for the transistor Tr2 and the inverter INV, even if an integrated IC or the like exists only for the transistor, there is no integrated IC, which has disadvantages in miniaturization and cost. .

Further, from the viewpoint of power consumption and heat generation, the forward voltage drop of the light emitting diode D1 is about 1.7 V at 20 mA for red LED of gallium aluminum arsenide, the on-voltage of the transistor Tr 1 is 0.1 V, the constant current element. The voltage of the FI is about 0.5 V, and when these are summed up, it becomes 2.3 V. The power consumption per dot when a current of 20 mA flows is 20 mA × 2.3 V = 46 mW.

On the other hand, the base-emitter voltage of the transistor Tr2 required for monitoring is as large as about 1 V, and the total power consumption of these is 20 + 46 = 66 mW, and the monitoring circuit occupies about 30% of the total power consumption It has been desired that the power consumption of this monitoring circuit be reduced.

[Means for Solving the Problems] In order to solve such a problem, an information display device according to the present invention is connected to a common power supply line of a plurality of light emitting diodes constituting a display block which is a set of a plurality of display dots. Current transformer, current detection means for detecting the current of the light emitting diode based on the output voltage of the current transformer, and control means for sequentially turning on and off the current supplied to the light emitting diode for each display dot. .

Further, a current value calculating means for calculating a current value flowing through the display block based on the number of display data specifying lighting of the display dots in the display block is provided.

Further, the apparatus further comprises a display data presence / absence detecting means for detecting presence / absence of display data for designating lighting of a display dot in the display block.

In addition, the power supply includes a first power supply for displaying a light-emitting diode, and a second power supply that outputs a higher voltage than the first power supply.

 Further, a switch is provided on the common power supply line.

[Operation] The control means for sequentially controlling the current supplied to the light emitting diode for each display dot performs on / off control of the current supplied in a cycle in which the turning on and off of the light emitting diode becomes invisible. An output voltage is induced from the current transformer connected to the common power supply line, and the current of the light emitting diode is detected by detecting the output voltage.

Further, the current value calculated by the current value calculation means and the current value detected by the current detection means are compared to detect an abnormality in the display state of the display block.

Further, it is determined whether or not the display data detected by the display data presence / absence detection means matches the presence / absence of the current value detected by the current detection means. As a result, an abnormality in the display state of the display block is detected.

Further, the current of the light emitting diode is changed from the second power source to the first power source.
, And the flowing current is detected.

Further, a current flowing through the common power supply line of the light emitting diode when the switch is opened is detected.

Example Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the information display device according to the present invention. 7, the same parts as those of the circuit of the conventional example shown in FIG. 7 are denoted by the same reference numerals. Note that the control circuit B corresponds to the control circuit A in FIG. The cathode of the light emitting diode D1 in the control circuit B is directly connected to the collector of a transistor Tr1 for controlling the turning on and off of the current of the light emitting diode D1, and the terminal O 'is connected to a storage circuit M for storing display data. Output is connected.
By making such a connection, the storage circuit MEM2 for storing the monitoring data stores the final data of the display data for controlling the switching of the current of the display dot for each display dot. By comparing the data of the two storage circuits of the storage circuits MEM1 and MEM2, it can be detected whether or not the display data has been correctly transmitted for each display dot.

Next, the power supply terminal PS provided for each display dot is
It is connected to a common line and connected to a power source E via a primary coil of a current transformer T. The secondary coil of the current transformer is connected to the current detector SE. The current detector SE detects the current flowing in the primary coil of the current transformer T based on the voltage generated in the secondary coil of the current transformer T, and outputs the detection result from a terminal SO. The terminal SO is connected to the terminal SI of the abnormality detector AC. The storage circuit MEM1 is connected to the other input terminal MI of the abnormality detector AC. Further, the output of the photoelectric converter LE is connected to the other input terminal LI of the abnormality detector AC.

The pulse generator PG receives the output of the photoelectric converter LE and outputs a signal in a state as shown in FIG.
This is output to the CP, and is output in a “0” level state during a relatively short time t3, and is output in a “1” level state during a relatively long time t4. , t4
Is set to such a short time that the light emitting diodes D1 to D64 are continuously turned on and off by the naked eye even after the light emitting diodes D1 to D64 are turned on and off.

At night, a signal in a state as shown in FIG. 2B is output to the terminal CP.

When the display data in the daytime is stored in the storage circuit M, the storage circuit M outputs the stored signal to the terminal O ′ and outputs the signal to one input terminal of the AND circuit AND. A signal in the daytime state shown in FIG. 2A is output to the output of the AND circuit AND. If this signal is "1", the transistor Tr1 turns on. At this time, the current is supplied from the power source E via the primary coil of the current transformer T to the terminal PS and the constant current element.
Through FI, the transistor Tr1 through the light emitting diode D1
To the power supply E via the terminal G through the collector / emitter of. When the signal in the daytime state shown in FIG. 2A becomes "0", the transistor Tr1 is turned off, and no current flows through the light emitting diode D1. When the signal becomes "1" again, the light emitting diode D1 is turned off. Current flows through That is,
Since the current of the primary coil of the current transformer T1 turns on and off, a voltage is induced in the secondary coil. Here, when the number of light-emitting diodes through which current flows among the light-emitting diodes D1 to D64 increases, the voltage generated in the secondary coil of the current transformer T changes accordingly.

The current detector SE outputs this detection result to the abnormality detector AC, and the abnormality detector AC calculates the current flowing through the light emitting diode from the display data of the storage circuit MEM1, and outputs the current to the current detector SE.
If they do not match as compared with the detection result of
Output to I. Here, the abnormalities that can be detected are 64 of the light emitting diodes D1 to D64, but the minority mismatch among the 64 is difficult to detect due to errors in the current detector SE, the current transformer T, etc. Can be detected, and the abnormality can be accurately detected in combination with the result of the coincidence comparator C.

At night, the abnormality detector AC is a photoelectric converter.
From the signal from LE and the display data of the memory circuit MEM1, the current flowing through the light emitting diode at night is calculated, and the current detector SE
Abnormality can be similarly detected by comparing with the detection result.
As a detection result of the detection result of the current detector SE, there is also a method of outputting whether or not a current has flowed to any one of the light-emitting diodes D1 to D64 in the display block. There is also a method of outputting a detection result in a form proportional to the number. Then, in the abnormality detector AC, when outputting a detection result as to whether or not any one of the currents of the light emitting diodes D1 to D64 has flowed, the abnormality is easily compared with the presence or absence of display data in the storage circuit MEM1. The output can be performed.

Here, the range of the current detection is set to the light emitting diodes D1 to D64. However, it is needless to say that the monitoring can be performed more minutely and finely, and the more the number can be collectively monitored. In addition, the power required for monitoring is not necessary for each display dot, and a voltage drop can be ignored for the primary coil of the current transformer T by using a through-type transformer or the like, so that power consumption can be reduced. In addition, power is required to operate the current detector SE and the abnormality detector AC.However, since power consumption can be suppressed by using low power consumption components such as a CMOS IC, a conventional power supply is required. Thus, unlike the case where the current detection circuit is provided for each display dot, power saving can be achieved. Further, since the light-off time of the light emitting diode is shortened (time t3) as shown in FIG. 2 (a), it does not become dark in the daytime.

Next, FIG. 3 is a block diagram showing a second embodiment of the information display device.

In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. FIG. 3 shows that a power supply E1 for current detection is separately provided in addition to the power supply E for display of the light emitting diode. The output voltage of the power supply E1 is set higher than the output voltage of the power supply E. The positive power supply of the power supply E1 supplies power to the base of the transistor Tr3 via the limiting resistor R. When a current flows through any of the light emitting diodes D1 to D64, the power supply E supplied to the base of the transistor Tr3
1 causes a current to flow through the emitter to the power supply E1 through the light emitting diode. This current value I is determined by the transistor Tr
If the base-emitter voltage of 3 is ignored, I = (E1-E) / R, and the transistor Tr3 can be turned on without fail. When the transistor Tr3 is turned on, the collector becomes "0" level, and the collector is connected to the input terminal of the inverter circuit INV1, so that the output of the inverter circuit INV1 is outputted at "1" level, and the state with current is abnormal. Output to the detector AC. On the other hand, when current does not flow through all of the light emitting diodes D1 to D64, the current path of the power supply E1 is cut off, so that the transistor Tr3 is turned off and the inverter circuit I
The output of NV1 is output at "0" level, and outputs a state of no current to the abnormality detector AC. The capacity of the power supply E1 needs to be a small-capacity power supply that only drives the transistor Tr3, and the pulse generator PG outputs "1" and "0" level signals in the daytime as shown in FIG. 2 (a). There is no need to output repeatedly alternately.

Next, FIG. 4 is a block diagram showing a third embodiment of the information display device.

In FIG. 4, the power supply E supplies light emitting diodes D1 to D6.
A switch S1 is provided between the four common lines, and the positive power supply of the power supply E is supplied to the base of the transistor Tr3 via the resistor R1. Normally, during display of the light emitting diode, the switch S1 is in the “ON” state, and only when current is detected, the switch S1 is in the “OFF” state. In this case, a light emitting diode
If a current flows through any of D1 to D64, power supply E
Of the positive power supply passes a current to the power supply E via the light emitting diode through the base / emitter of the transistor Tr3. As a result, the transistor Tr3 is turned on, and the same operation as the operation described with reference to FIG. 3 is performed thereafter.

Next, FIG. 5 is a block diagram showing a fourth embodiment of the information display device.

5, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

The pulse generator PG 'receives the signal of the photoelectric converter LE and outputs the pulses shown in FIG. 6 to the terminals CP1 to CP64 with their pulse widths changed during the daytime and at night. The output of terminal CP1 is connected to terminal P of control circuit A 'for driving light emitting diode D1.
Is connected to the input terminal of the AND circuit AND.
The output of the terminal CP2 is connected to the input terminal of the AND circuit AND via the terminal P of the control circuit A 'for driving the light emitting diode D2. Hereinafter, similarly, the terminals CP3 to CP64
Are also connected to respective terminals of an AND circuit AND via respective terminals P of a control circuit A 'for driving the light emitting diodes D3 to D64. The terminals CP1 to CP64 are connected to one input terminals of the AND circuits AND1 to AND64, respectively, and the other input terminals of the AND circuits AND1 to AND64 are all connected to output the current detection signal of the current detector CS. Connected to terminal SO.

The current detector CS may be any of the current transformer type shown in FIG. 1 and the transistor type shown in FIG. 3, and when a current flows through any of the light emitting diodes D1 to D64, " 1 "state signal is output. Outputs of the AND circuits AND1 to AND64 are connected to a storage circuit MEM2, and output signals thereof are output to storage elements corresponding to the light emitting diodes D1 to D64, respectively. At the time T1 in FIG. 6, only the state of the terminal CPU1 is the state "1", and the AND circuit AND of the control circuit A 'corresponding to the light emitting diode D1 and the gate of the AND circuit AND1 are opened. Here, if the storage output of the storage circuit M in the control circuit A 'is state "1", the transistor Tr
1 turns on, a current flows through the light emitting diode D1, and the terminal SO of the current detector CS outputs a signal of state "1". At this time, since the gate of the AND circuit AND1 is open, the storage circuit MEM2 stores the state “1” in the storage element corresponding to the light emitting diode D1. On the other hand, if the current does not flow through the light emitting diode D1 for some reason, the terminal SO of the current detector CS
Becomes the state "0", and the storage element corresponding to the light emitting diode D1 of the storage circuit MEM2 stores the state "0".

That is, at time T1 in FIG. 6, the state of the current of the light emitting diode D1 is stored in the storage circuit MEM2. Next, at time T2 in FIG. 6, the pulse generator P
Since only the terminal PC2 of G 'is in the state "1", the AND circuit AND of the control circuit A' corresponding to the light emitting diode D2 and the gate of the AND circuit AND2 are opened. Therefore, the state of the light emitting diode D2 is stored in the storage circuit MEM2.

Similarly, at time T3 to time T64 in FIG. 9, the state of the current flowing through the light emitting diodes D3 to D64 is changed to the storage circuit MEM2.
Is stored. That is, the current state of all the light emitting diodes D1 to D64 is detected by the current detection circuit CS, and the memory circuit MEM2
Can store this.

In the driving timing of the light emitting diode during the daytime in FIG. 6 (corresponding to the diagrams (a) and (b) of FIG. 6), only the terminal corresponding to the light emitting diode for detecting the current state during the time t3 is set to the state It is set to “1”, the other terminals are set to the state “0”, and all the terminals are set to the state “1” during the time t4. This is because in the daytime, it is necessary to increase the luminous intensity of the light-emitting diode, so that the time of the state "1" is increased. Like that.

On the other hand, in the nighttime (corresponding to FIGS. 6 (e) to 6 (h)), only the terminal corresponding to the light emitting diode for detecting the current during the time t1 is set to the state “1”, and the other terminals are set to the state “1”. It is "0". At the time t2, all the terminals are in the state “0”. This is because it is necessary to reduce the luminous intensity of the light emitting diode at night, so the time of the state “0” is increased, and this time also repeats times t1 and t2 at a fast cycle to prevent flickering. I have.
When the luminous intensity of the light emitting diode is too dark, the state “0” may be changed to the state “1” for a certain period of time, as indicated by the dotted line shown in FIG. In addition, the current detector CS
Is a current transformer method, the pulse waveform may be divided as indicated by the dotted line shown in FIG. 6b.

In the description of FIG. 5, the AND circuits AND1 to AND64 are provided as inputs of the storage circuit MEM2, and the output signals of the pulse generator PG 'are stored in the storage elements corresponding to the light emitting diodes D1 to D64. However, time T1, T in FIG.
At the time of 2, T3,..., T64, circuits to be stored in the storage circuit MEM2 are omitted, but various methods such as using a microcomputer or the like can be considered for these storage means.

Also, as for the control circuit A 'described in FIG. 5, 16 control circuits A' are already integrated in a commercially available IC, that is, TD62C850N or the like. For the 16 circuits in this IC, the input terminal P of the AND circuit AND in the control circuit A '
Are provided in common to 16 circuits. In general, since many ICs are used when constructing a display panel, in the case of an IC configured as described above, a set of ICs for each circuit number is used as a display block, and a current detection circuit is used for each circuit number. By providing CS, the number of components can be reduced. When the TD62C85ON is used, the current detector CS is a simple circuit, and the number of components can be reduced and the size can be reduced by using an IC. Further, in the present invention, the current detector CS is provided on the positive power supply side of the power supply E. However, this may be provided on the negative power supply side. May be used.

As described above, according to the present invention, one light emitting diode is used.
Lights are sequentially selected and turned on in a time-sharing manner, and the current of the power supply supplied to the light-emitting diode is detected at this selected timing. This reduces the number of parts and ICs.
As a result, the size can be reduced, and the reliability can be improved by reducing the number of connectors.

Further, since a commercially available IC can be used for the parts to be used, the device can be configured at low cost.

Although the present embodiment has been described using a red monochromatic light emitting diode, this light emitting diode may be a yellow-green diode or a diode of another color, or may be a light emitting diode of two or more colors. Further, in the description of the configuration of the display dots, a single light emitting diode has been described as an example, but the configuration of the display dots may be configured by a plurality of light emitting diodes. Further, in the present embodiment, the on / off control of the light emitting diodes is simultaneously performed by the output of the pulse generator.In this case, however, current flows simultaneously to all the light emitting diodes, and as a result, noise may be generated. Because it is possible,
The light emitting diode may be divided into a plurality of blocks, or the time for ON / OFF control for each display dot may be different.

[Effects of the Invention] As described above, the information display device according to the present invention includes:
Since the current flowing in the light emitting diode is sequentially turned on and off for each display dot and the current flowing in the common power supply line of a plurality of light emitting diodes is detected at once, the number of components constituting the information display device is reduced and the IC is reduced. As a result, the size of the device can be reduced, the reliability can be improved, and the power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining an embodiment of an information display device according to the present invention, FIG. 2 is a timing chart thereof, and FIGS. 3 to 5 explain second to fourth embodiments of the information display device. FIG. 6 is a timing chart of FIG.
FIG. 1 is a block diagram of a conventional information display device, FIG. 8 is a block diagram of a display element of this device, and FIG. 9 is a timing chart of the conventional device. LE: Photoelectric converter, PG, PG ': Pulse generator, A', B
…… Control circuit, M, MEM1, MEM2 …… Storage circuit, AND, AND1, AN
D2, AND64: AND circuit, Tr1, Tr3: Transistor, D
1 to D64: Light-emitting diode, FI: Constant current element, AC:
Abnormality detector, C: Match comparison detector, T: Current transformer, SE, CE: Current detector, E, E1: Power supply.

Continuation of front page (58) Fields investigated (Int.Cl. ⁶ , DB name) G08G 1/095 G09G 3/00-3/34 G09F 9/33

Claims (5)

(57) [Claims] 1. An information display for displaying characters and figures by dot spelling by arranging display dots in a matrix and arbitrarily illuminating display dots among the display dots. In the apparatus, a current transformer connected to a common power supply line of a plurality of light emitting diodes constituting a display block, which is a set of a plurality of display dots, and current detection for detecting current of the light emitting diodes based on an output voltage of the current transformer And control means for sequentially turning on and off the current supplied to the light emitting diode for each display dot, wherein the control means controls the on and off of the current flowing in a cycle in which turning on and off of the light emitting diode becomes invisible. To generate an output voltage from the current transformer, and cause the current detecting means to detect the current flowing through the light emitting diode. An information display device characterized in that: 2. An information display for displaying characters and figures by dot spelling by arranging the display dots in a matrix and arbitrarily illuminating display dots among the display dots. In the device, a current detecting means connected to a common power supply line of a plurality of light emitting diodes constituting a display block, which is a set of a plurality of display dots, for detecting a current flowing through the plurality of light emitting diodes; Control means for sequentially controlling ON / OFF for each display dot, and current value calculation means for calculating a current value flowing through the display block based on the number of display data specifying lighting of the display dot in the display block, An abnormality in the display state of the display block is detected by comparing the current value calculated by the value calculation means with the current value detected by the current detection means. An information display device, characterized in that: 3. The display data presence / absence detection means according to claim 1, further comprising display data presence / absence detection means for detecting presence / absence of display data designating lighting of a display dot in said display block. An information display device for detecting an abnormality in the display state of the display block by comparing the current value detected by the current detection means with a current value detected by the current detection means. 4. An information display for displaying characters and figures by dot spelling by arranging the display dots in a matrix and arbitrarily illuminating display dots among the display dots. In the device, a current detecting means connected to a common power supply line of a plurality of light emitting diodes constituting a display block, which is a set of a plurality of display dots, for detecting a current flowing through the plurality of light emitting diodes; Control means for sequentially controlling on / off for each display dot; a first power supply for displaying the light emitting diode; and a second power supply for outputting a voltage higher than the first power supply, wherein the current detection means An information display device for detecting a current of the light emitting diode flowing in a direction from the second power supply to the first power supply. 5. An information display for displaying characters and figures by dot spelling by arranging the display dots in a matrix and emitting arbitrary display dots among the display dots by using light emitting diodes as display dots. In the device, a current detecting means connected to a common power supply line of a plurality of light emitting diodes constituting a display block, which is a set of a plurality of display dots, for detecting a current flowing through the plurality of light emitting diodes; Control means for sequentially controlling ON / OFF for each display dot, and a switch connected to the common power supply line, wherein the current detection means detects a current of the light emitting diode flowing through the common power supply line when the switch is opened. An information display device for detecting.