JPH0423100A - Information display device - Google Patents

Abstract

PURPOSE:To improve the reliability by controlling turning-on/off of the current of a light emitting diode with one display dot as the unit and collectively detecting the current of a common power line. CONSTITUTION:The collector of a transistor TR Tr1 which controls turning-on/off of the current is directly connected to the cathode of a light emitting diode D1 in a control circuit B, and the output of a storage circuit M where display data is stored is connected to a terminal O'. Final data of display data which controls turning-on/off of the current of each display dot is stored in a storage circuit MEM2 where monitor data is stored, and a match comparing circuit C compares data in both storage circuits MEM1 and MEM2 with each other to detect whether display data is correctly transmitted or not with one display as the unit. Thus, the reliability is improved.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is an information display device in which light emitting diodes are arranged in a display dot configuration, and the display dots are arranged in a matrix in the vertical and horizontal directions to display dotted information. It is.

[Conventional technology] Conventionally, display dots are arranged vertically and horizontally on a matrix.
Traffic information boards, road information boards, etc. are examples of information display devices that display display dots in dot format. The display elements of these display boards are red.

Light emitting diodes are used because they can display multiple colors such as yellow-green.

In addition, since these information boards are placed outdoors in harsh environmental conditions, the display condition may be disrupted due to temperature rise due to sunlight exposure, component failure due to vibration from road traffic, or poor connection of connectors. There is. on the other hand,
Since road information boards display information such as cliff collapses and other important information such as stopping passing vehicles, disruption of such displays is a serious problem. Conventionally, the current flowing through each display dot in the light emitting diodes that make up the display dots on the display surface is detected, and disturbances in the display state are detected by comparing this detected data with display data that specifies the display content. However, if an abnormality occurs, an alarm is output.

Specific examples of such conventional information display devices are shown in FIGS.
This will be explained using figures.

FIG. 8 shows a part of the display surface formed by each display dot, and shows this part in an extracted form. D1
~D64 is a light emitting diode, and the shaded area indicates that the light emitting diode emits light and is displayed, and here is an example in which a katakana character "A" is displayed. Moreover, FIG. 7 is a circuit diagram that performs these displays.

In FIG. 7, D1 to D64 are light emitting diodes that make up the display surface of FIG. 8, and the circuits that drive these individual light emitting diodes and the circuit that detects the current flowing through the light emitting diodes are controlled by the dashed line. In circuit A, all the configurations of this control circuit A are the same. This control circuit A
In the figure, M is a storage circuit that stores display data for displaying display dots. This storage data is transferred from the storage circuit MEM1 through a terminal and stored. The output of the memory circuit M becomes the input of the AND circuit AND, and the other input of the AND circuit AND is connected to the terminal P.
The output terminal CP of the pulse generator PG is connected through it.

The pulse generator PG receives a signal from a charging converter LE such as a rechargeable automatic flasher, and outputs the state "1" to the terminal CP during the day as shown in FIG. 9(a), and at night. , in Figure 9 (
b) As shown in the figure, a pulse signal is generated that periodically outputs a "1" state at time t1 and outputs a "0" state at time t2. Therefore, the AND circuit AND
If there is display data, the output will be in a state similar to that shown in FIG.
'' level, it becomes the base current of the transistor Tri, turning on the transistor Trl. Further, a constant current element FI such as a resistor, a constant current diode, a constant current circuit, etc. is connected to the anode of the light emitting diode D1, and receives power supply from a power source E via a terminal PS. and,
When the transistor Tr 1 is turned on, a current flows through the light emitting diode DI, which becomes the base current of the transistor Tr 2 via the cathode, and as a result, the current flows from the emitter of the transistor Tr 2 to the collector and emitter of the transistor Tri. Flows to power supply E. When the base current flows, the transistor Tr2 turns on and sets the input of the inverter INV to "0", so the output becomes "1" and is outputted from the terminal O and stored in the memory circuit MEM2.

On the other hand, a negative number comparison detector C is connected to the memory circuits MEMI and MEM2, and this negative number comparison detector C compares the data of both memory circuits, and outputs a signal to the AR terminal in the case of a mismatch. , to issue a warning. Here, the reason why the pulse generator PG is provided and the output of the AND circuit AND is output only for time t1 at night is to shorten the current flowing through the light emitting diode so that it becomes dark and does not cause halation. In addition, the time t1 is set so that the operation is repeated at high speed so that even if the light emitting diode turns on and off, it can be seen continuously by the naked eye due to the afterimage phenomenon.
and t2 are selected.

[Problems to be Solved by the Invention] In FIG. 7, looking at the circuit for monitoring, one display dot requires a transistor T r 2 .

Since the inverter INV and the memory circuit MEM are required, as well as the terminal O, the information display device requires an enormous number of components as the number of display dots increases.

For example, if you place one display dot on a display surface of 2 m, x 4 m,
When arranged in 0 dragon pitch, the number of displayed dots is 200X
Since 400=80,000 dots are required and the number of parts for monitoring is the product of the number of terminals, there is a problem in that the cost is high.

Furthermore, from the standpoint of reliability of information display devices, the large number of parts required for monitoring means a high failure rate, and the failure rate of the monitoring circuit provided to monitor disconnection of light emitting diodes is high. There was also the problem that reliability deteriorated. Also, a memory circuit M, which is a circuit for display, and an AND circuit AND.

The transistor T r 1, constant current element, etc. are commercially available as an integrally integrated IC. For example, T
According to the D62C85ON, one IC can drive 16 display dots with a constant current, which is advantageous in terms of size reduction and cost. However, regarding the transistor Tr2 and the inverter INV, even if there are ICs that integrate the transistor, there is no one that integrates them in one piece, and this has drawbacks in terms of miniaturization and cost. .

Furthermore, from the viewpoint of power consumption and heat generation, the forward voltage drop of the light emitting diode D1 is about 1.7■ at 20 mA for a red LED made of gallium aluminum arsenide, etc.
The on-voltage of the transistor T r 1 is 0. The voltage of IV and constant current element FI is about 0.5■, and the total of these is 2.3■, and the power consumption per dot when a current of 20mA flows is 20mAX2.3V=46mW. Become.

On the other hand, the base-emitter voltage of transistor Tr2 required for monitoring is as large as IV, and the total power consumption is 20 + 46 = 66 mW, and the monitoring circuit consumes about 30% of the total power consumption. Therefore, it has been desired to reduce the power consumption of this monitoring circuit.

[Means for Solving the Problems] In order to solve such problems, an information display device according to the present invention uses a collection of a plurality of display dots as a display block,
A device comprising current detection means for collectively detecting the current flowing through the common power supply line of the plurality of light emitting diodes constituting this display block, and control means for sequentially controlling the on/off of the current flowing through the light emitting diodes for each display dot. It is.

Additionally, the common power line is equipped with a current transformer.

The present invention also includes a current value calculation means for calculating a current value flowing through the display block based on the number of display data specifying lighting of display dots in the display block.

The apparatus also includes display data 1 non-detecting means for detecting the presence or absence of display data specifying lighting of display dots in the display block.

Further, a first power source for displaying a light emitting diode, and a first power source for displaying a light emitting diode;
The second power source outputs a voltage higher than that of the power source.

In addition, it is equipped with a switch on the common power line.

[Operation] Based on the on/off control of the control means, the display dots in the display block are selected one by one, and the current flowing through the display dots is sequentially detected.

Furthermore, on/off control of the first current flowing through the light emitting diode is performed at a high-speed cycle, a voltage is induced from the current transformer, and the current of the light emitting diode is detected by detecting this 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 the presence or absence of display data detected by the display data presence/absence detection means matches the presence or absence of a current value detected by the current detection means, and as a result, an abnormality in the display state of the display block is detected.

Further, the current of the light emitting diode flows in the direction from the second power source to the first power source, and this flowing current is detected.

Furthermore, when the switch is opened, the current flowing through the common power supply line of the light emitting diodes is detected.

It is equipped with the following.

[Example] Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an information display device according to the present invention. In the same figure, the same parts as those of the conventional circuit shown in FIG. 7 are given the same reference numerals, and the control circuit B corresponds to the control circuit A shown in FIG. vi
At the cathode of the light emitting diode D1 in the control circuit B, there is a transistor T that controls the on/off of the current of the light emitting diode D1.
The collector of r1 is directly connected to the terminal O', and the output of a memory circuit M storing display data is connected to the terminal O'. By making such a connection, the memory circuit MEM2 that stores the monitoring data stores the final data of the display data that controls the on/off of the current of the display dot for each display dot, and the number comparison circuit C Now, the memory circuit ME
By comparing the data of both memory circuits MI and 2,
It is possible to detect whether display data is 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 the primary coil of a current transformer T. The secondary coil of the current transformer is connected to a current detector SE. and,
The current detector SE detects the current flowing through the primary coil of the current transformer T based on the voltage generated in the secondary coil of the current transformer T, and sends this detection result to the terminal so.
Output from. Note that the terminal SO is connected to the terminal SI of the abnormality detector AC. Furthermore, a memory circuit MEMI is connected to the other input terminal Mr of the abnormality detector AC.

Further, the output terminal 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 the state shown in FIG. output in the "o" level state for a relatively long time t4.
This outputs the question at the "1" level, and this time t
3. The repetition time of t4 is the light emitting diode D1 to D6.
Even if 4 is turned on or off, the time is such that it can be seen continuously with the naked eye due to an afterimage phenomenon.

Further, at night, a signal in the state shown in FIG. 2(b) is outputted to the terminal CP.

When the memory circuit M stores the display data of the daytime state, the memory circuit M outputs this stored signal to the terminal O' and also outputs it to one input terminal of the AND circuit AND. A daytime state signal shown in FIG. 2(a) is outputted from the AND circuit AND.

If this signal is in the "1" state, the transistor Tri is turned on, and at this time, the current flows from the power source E through the primary coil of the current transformer T, from the terminal PS through the constant current element FI, and from the light emitting diode. When the daytime state signal shown in FIG. 2(a), which flows through D1, the collector-emitter of the transistor Trl, and the terminal G to the power supply E, becomes "0", the transistor Tri is turned off. Current no longer flows through the light emitting diode DI,
When the state becomes "1" again, current flows through the light emitting diode D1. That is, since the current in the primary coil of the current transformer T1 is turned 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 significantly 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 memory circuit MEM1, and compares it with the detection result of the current detector SE. If they do not match, it is output to terminal ARI as an error. Here, the abnormalities that can be detected are 64 light emitting diodes D1 to D64, but for a small number of mismatches among the 64, the current detector SE
, although it is difficult to detect due to errors in the current transformer T, etc.
A large discrepancy can be detected, and when combined with the result of the matching comparator C, an abnormality can be accurately detected.

Furthermore, regarding nighttime, the abnormality detector AC calculates the current flowing through the light emitting diode at night from the signal from the photoelectric converter LE and the display data of the storage circuit MEM1, and compares it with the detection result of the current detector SH. Abnormalities can be detected in the same way. As the detection result of the current detector SE, there is also a method of outputting whether or not 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 detection results in proportion to the number of . In the abnormality detector AC, when outputting the detection result as to whether or not a current has flowed through any one of the light emitting diodes D1 to D64, it is possible to easily output the detection result by comparing it with the presence or absence of display data in the memory circuit MEMI. The output can be done.

Here, the current detection range is set to the light emitting diodes D1 to D64.
However, it goes without saying that it is possible to monitor in detail by using a smaller number, and it is possible to monitor all at once by using a larger number.Also, when looking at the power required for monitoring, the power required for each display dot is In addition, since the voltage drop can be ignored by using through-type transformers for the primary coil of the current transformer T, it is possible to reduce power consumption. In addition, electric power is required to operate the current detector SE and abnormality detector AC, but these are
Since power consumption can be suppressed by using components with low power consumption such as C, it is possible to save power, unlike the conventional case where a current detection circuit is provided for each display card. In addition, since the turn-off time of the light emitting diodes is shortened (time t3) as shown in FIG. 2(a), it does not become dark during the daytime.

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

In this figure, the same parts as those in FIG. 1 are given the same reference numerals, and the explanation thereof will be omitted. In FIG. 3, a current detection power source E1 is separately provided in addition to the display power source E for the light emitting diode, and the output voltage of the power source E1 is set higher than the output voltage of the power source E. The positive power source of the power source E1 supplies power to the base of the transistor T r 3 via the limiting resistor R. When a current flows through any of the light emitting diodes D1 to D64, the power source E1 supplied to the base of the transistor T r 3 causes the current to flow through the emitter and through the light emitting diode to the power source E1. This current value I becomes I=(El-E)/R when the base-emitter voltage of the transistor Tr3 is ignored, and the transistor Tr3 can be turned on reliably. When the transistor T r 3 is turned on, the collector becomes "0" level, and since the collector is connected to the input terminal of the inverter circuit INVI, the output of the inverter circuit INVI is outputted at the "1" level, and there is current. will be output to the abnormality detector AC. On the other hand, if current does not flow through all of the light emitting diodes D] and ~D64,
Since the current path of the power source E1 is disconnected, the transistor Tr
3 is turned off, and the output of the inverter circuit INVI becomes "0".
” level, and the state of no current is detected by the abnormality detector AC.
Output to. The capacity of the power supply E1 is only small enough to drive the transistor Tr3, and the pulse generator PG can output 'IJ, 'O in the daytime state as shown in FIG. 2(a).
There is no need to alternately and repeatedly output J level signals.

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

In FIG. 4, light emitting diodes D1 to D are connected to the power source E.
A switch S1 is provided between the 64 common lines, and the power supply E
The positive power supply is supplied to the base of the transistor Tr3 via the resistor R1.

Normally, when the light emitting diode is displaying, the switch S1 is set to "
The switch S1 is turned on, and the switch S1 is turned off only in the case of current detection. In this case, the light emitting diodes D1 to D64
If a current is flowing in either of them, the positive power source of the power source E will cause current to flow to the power source E through the base and emitter of the transistor T r 3 and through the light emitting diode. As a result, the transistor Tr3 is turned on, and the same operation as that described with reference to FIG. 3 is performed thereafter.

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

In FIG. 5, parts equivalent to those in FIG. 1 are denoted by the same reference numerals, and their explanation will be omitted.

The pulse generator PG' receives the signal from the photoelectric converter LE and outputs the pulses shown in FIG. 6 to the terminals CPI to CP64 with different pulse widths during the day and at night. Terminal CP
The output of I is the control circuit A that drives the light emitting diode D1.
' is connected to the input terminal of the AND circuit AND via the terminal P of '.

Further, the output of the terminal CP2 is connected to the AND circuit AND via the terminal P of the control circuit A'' that drives the light emitting diode D2.
is connected to the input terminal of Similarly, terminal CP
3 to CP64 are also connected to the AND circuit A through the terminals P of the vi control circuit A° that drives the light emitting diodes D3 to D64.
It is connected to each terminal of ND. Also, terminal C
PI to CP64 are each connected to one input terminal of the AND circuits ANDI to AND64, and the other input terminals of the AND circuits AND1 to AND64 are all connected to the current detection signal output terminal SO of the current detector C8. It is connected.

The current detector C8 may be of any type, such as the current transformer type shown in FIG. 1 or the transistor type shown in FIG. 3. When a current flows through any of the light emitting diodes D1 to D64, " Outputs a signal in the “1” state. The outputs of the AND circuits AND1 to AND64 are connected to the memory circuit MEM2, and the output signals thereof are output to the memory elements corresponding to the light emitting diodes D1 to D64, respectively. At time T1 in FIG. 6, only the state of the terminal CPI is "1", and the gates of the AND circuit AND and the AND circuit AND■ of the control circuit A' corresponding to the light emitting diode D1 are opened. Here, if the memory output of the memory circuit M in the front of the control circuit is in the state "1", the transistor Tri is turned on and current flows through the light emitting diode D1, and the terminal So of the current detector C8 is in the state "1". ” signal is output. At this time, since the gate of the AND circuit ANDI is open, the memory circuit ME
M2 sets the memory element corresponding to the light emitting diode D1 in the state r1. to remember. On the other hand, if current does not flow through the light emitting diode D1 for some reason, the terminal SO of the current detector CS will be in the state "0", so the memory element corresponding to the light emitting diode D1 in the memory circuit MEM2 will be in the state "0". I will remember it.

That is, at time TI in FIG. 6, the current state of the light emitting diode D1 is stored in the memory circuit MBM2. Next, at time T2 in FIG. 6, since only the terminal CP2 of the pulse generator PG' is in the state R'IJ, the AND circuit AND of the control circuit A' corresponding to the light emitting diode D2 and the AND circuit AND2 gate will be opened.

Therefore, the state of the light emitting diode D2 is stored in the memory circuit MEM2.

Similarly, from time T3 to time T64 in FIG. 9, the state of the current flowing through the light emitting diodes D3 to D64 is stored in the memory circuit MEM2. That is, current detection circuit C8
The current states of all the light emitting diodes D1 to D64 can be detected and stored in the memory circuit MEM2.

At the drive timing of the light emitting diode during the daytime in Fig. 6 [corresponding to figures (a) to (b) in the same figure], only the terminal corresponding to the light emitting diode that detects the current state during time t3 is controlled. R is set to "1", and the other terminals are in the state "
0'', and all terminals are in the state ``1'' during time t4.
'', which means that during the daytime, it is necessary to increase the luminous intensity of the light emitting diode, so the time in state ``1'' is increased, and the time t3. By repeating t4 at a fast cycle, the light emitting diodes D1 to D64 are prevented from flickering.

On the other hand, at night [corresponding to Figures (e) to (h) in Figure 6], only the terminal corresponding to the light emitting diode that detects the current during time t1 is in the state []-J, and the other terminals are in the state []-J. Condition R
It is set as "O". Furthermore, at time t2, all terminals are in the state r□. This is due to the fact that it is necessary to reduce the luminous intensity of the light emitting diode at night.
'OJ time is increased, and in order to prevent flickering, times t1 and t2 are repeated at a fast cycle. If the luminous intensity of the light emitting diode is too low, as shown by the dotted line a in FIG. 6, for a certain period of time,
State "0" is set to state r1. Alternatively, if the current detector C8 is of a current transformer type, the pulse waveform may be divided as shown by the dotted line b in FIG.

Furthermore, in the explanation of FIG. 5, it was explained that the AND circuits AND1 to AND64 were provided as inputs to the memory circuit MEM2, and the output signals of the pulse generator PG' were stored in the memory elements corresponding to the light emitting diodes D1 to D64. . However, at times T1, T2 in FIG. T3. ..., Te3
At this point, the circuit for storing data in the memory circuit MEM2 is omitted, but regarding these storage means,
Various methods can be considered, such as using a microcomputer or the like.

Furthermore, regarding the control circuit A° explained in FIG. 5, 16 control circuits A° are already integrated in a general commercially available IC1, ie, TD62C85ON, etc. For the 16 circuits in this IC, AND circuit A in control circuit A'
The input terminal P of the ND is shared by 16 circuits. Generally, when configuring one display board, many ICs are used.
In the case of an IC configured as above,
A display block is a collection of a plurality of ICs for each circuit number, and the number of parts can be reduced by providing a current detection circuit Cst for each circuit number. Also, the above T
When D62C85ON is used, the current detector C8 becomes a simple circuit, and the effect of reducing the number of parts and miniaturization by using an IC can be achieved. Further, in the present invention, the current detector C8 is provided on the positive power side of the power source E, but it may be provided on the negative power side. May be used.

As explained above, the present invention sequentially selects the light emitting diodes one by one and turns them on in a time-sharing manner, and detects the current of the power supply supplied to the light emitting diodes all at once at the selected timing. Therefore, the number of parts and IC
This makes it possible to reduce the size of the device, and improves reliability by reducing the number of connectors.

Furthermore, since commercially available ICs can be used as the parts used, the device can be configured at a low cost.

Although this embodiment has been described using a red monochromatic light emitting diode, this light emitting diode may be a yellowish green diode or another color diode, or may be a light emitting diode of two or more colors. In addition, in explaining the configuration of display dots,
Although the description has been made using a single light emitting diode as an example, the structure of the display dot may be formed by a plurality of light emitting diodes. Furthermore, in this embodiment, it has been explained that the on/off control of the light emitting diodes is performed simultaneously by the output of the pulse generator.
In this case, current flows through all the light emitting diodes at the same time,
Since noise may occur as a result, the light emitting diode may be divided into a plurality of blocks, or the on/off control time may be changed for each display dot.

[Effects of the Invention] As explained above, the information display device according to the present invention sequentially controls on/off the current flowing through the light emitting diodes for each display dot, and collectively controls the current flowing through the common power line of a plurality of light emitting diodes. This makes it possible to reduce the number of parts that make up the information display device and make it more compact by using ICs.As a result, the device can be constructed at a lower cost, has improved reliability, and has lower power consumption. This has the effect of making it possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram explaining one embodiment of the information display device of the present invention, FIG. 2 is a timing chart of the information display device, and FIGS. 3 to 5 explain second to fourth embodiments of the information display device. The block diagram shown in Figure 6 is the timing chart, and Figure 7 is
The figure is a block diagram of a conventional information display device, FIG. 8 is a configuration 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,
MEMI, MEM2...-Memory circuit, AND, AND
I, AND2. AND64...AND circuit, Tri
, Tr3...transistor, D1-D64-...
Light emitting diode, FI---constant current element, AC...
・Anomaly detector, C...-Number comparison detector, T...
Current transformer, SE, CE...Current detector, E
, El...Power supply.

Claims (6)

[Claims] (1) Information that uses light-emitting diodes as display dots, arranges the display dots in a matrix in the vertical and horizontal directions, and displays characters, figures, etc. in a dotted manner by emitting light from any display dot among the display dots. In a display device, a collection of a plurality of display dots is used as a display block, and a current detection means for collectively detecting a current flowing in a common power supply line of a plurality of light emitting diodes constituting the display block; A control means for sequentially controlling on/off of each display dot, and selecting display dots in the display block one by one based on the on/off control of the control means and detecting the current flowing through the display dots sequentially by time-sharing control. An information display device characterized by: (2) The information display device according to claim (1), wherein the common power supply line includes a current transformer, and the control means controls the current flowing through the light emitting diodes at a high-speed cycle in which it is difficult to distinguish between turning on and turning off the light emitting diodes. An information display device characterized in that an output voltage is generated from the current transformer by performing on/off control of the current transformer, and the current detecting means detects the current of the light emitting diode by detecting the output voltage. (3) The information display device according to claim (1), comprising current value calculation means for calculating a current value flowing through the display block based on the number of display data specifying lighting of display dots in the display block, An information display device configured to detect an abnormality in the display state of a display block by comparing the current value calculated by the current value calculation means and the current value detected by the current detection means. (4) The information display device according to claim (1), further comprising display data presence/absence detection means for detecting the presence or absence of display data specifying lighting of display dots in the display block, wherein the display data presence/absence detection means detects the presence/absence of display data. An information display device configured to detect an abnormality in a display state of a display block by comparing the presence or absence of displayed data and the presence or absence of a current value detected by the current detection means. (5) The information display device according to claim (1), comprising: a first power source for displaying the light emitting diode; and a second power source that outputs a voltage higher than the first power source; An information display device configured to detect a current flowing through the light emitting diode from a second power source toward a first power source. (6) The information display device according to claim (1), wherein the common power supply line includes a switch, and the current detection means detects the current of the light emitting diode flowing through the common power supply line when the switch is opened. information display device.