JPH0422989A - Information display device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the luminous intensity of emitted light caused by temperature rise by switching a display position on a display surface in the case of changing display. CONSTITUTION:Luminous display elements D1-D64 are taken as display dots, which are longitudinally and laterally disposed in a matrix state and allowed to emit light. Then, a means for changing the position of the display dot which starts the display in the case of changing the display is provided. Namely, shift registers SR1-SR8 are used as means for transferring display command data from a storage circuit MEM1 to the driving circuit of the light emitting diodes D1-D64 and the position of the display is changed by controlling the number of data transfer. Therefore, the identical display dot is not kept lighting and all of the display dots are averagely lighted. Thus, the deterioration of the luminous intensity and the temperature rise are reduced in the display element like the light emitting diodes D1-D64.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an information display in which display dots are arranged in a matrix in a vertical and horizontal manner to display dots using self-luminous display elements such as light bulbs or light emitting diodes. It is related to the device.

[Conventional technology] Conventionally, display dots are arranged vertically and horizontally in a matrix.
Traffic information boards, billboards, etc. are examples of information display devices that display display dots, but the display dots of these outdoor information display devices are self-luminous displays such as small light bulbs and neon tubes. It is used because the element is bright and easy to see. Furthermore, recently, light emitting diodes have come to be used as display elements because of their ability to display multiple colors such as red, yellow-green, etc., and their long lifespan.

[Problems to be Solved by the Invention] These self-luminous display elements used outdoors need to be lit brightly, but when a small light bulb is lit brightly,
Their average lifespan is short, about 5,000 hours, and there have been problems with replacement and maintenance on traffic information boards displayed on expressways. Similarly, neon tubes have a similar problem, as their lifespan increases depending on the lighting time. Furthermore, due to the nature of semiconductors, light-emitting diodes do not have a lifetime when their cores are broken, but as shown in the graph of luminous intensity drop per operating time in Figure 7, they have the characteristic that their luminous intensity decreases when they are turned on for a long period of time. , the luminous intensity of a light-emitting diode is approximately proportional to the current flowing through the light-emitting diode, so if a large amount of current is passed to make the light shine brightly outdoors, the characteristic A is shown in Figure 7.
The decrease in luminous intensity is also large between 20 mA as shown in and 50 mA as shown in characteristic B. Furthermore, as can be seen by comparing characteristics B and C shown in Figure 7, the luminous intensity of light-emitting diodes decreases more with respect to lighting time as the ambient temperature rises; There is a problem in that self-heating occurs, and when it is turned on for a long time, the self-heating raises the ambient temperature and causes a large decrease in luminous intensity. Recently, as shown in the display example of a graphical information board in Fig. 8, road route shapes are displayed as dots D, and points where traffic congestion occurs are marked as areas ``A'' in Fig. 8. As shown, the display dots are displayed with fine hatching, and the display dots are displayed in red or orange by simultaneously lighting yellow and green to indicate the degree of traffic congestion.

In such cases, the display dots indicating the route shape do not go out and remain lit, so the luminance often decreases compared to other display dots, and when changing the route shape, other display dots A difference in luminous intensity with the dots occurred, which was a problem. In addition, if the display dots are made to emit light simultaneously over a large area as shown by the fine hatching shown in Figure 8, the self-heating of the light emitting diodes will heat up the other display dots. , there is a problem that the ambient temperature of the light-emitting diode becomes higher and the luminous intensity decreases more.Furthermore, the luminous intensity of the light-emitting diode has a characteristic that the higher the ambient temperature, the lower the luminous intensity, as shown in the ambient temperature vs. luminous intensity characteristic in Figure 9. The light emitting diode's allowable current decreases as the ambient temperature rises, as shown in the absolute maximum forward current reduction characteristics in Figure 10, so current cannot flow and the desired luminous intensity cannot be achieved. There was a problem that it became impossible to obtain.

[Means for Solving the Problems] In order to solve such problems, the information display device according to the present invention is provided with means for changing the position of a display dot at which display starts when changing the display. Further, another invention is provided with a timer that starts measuring from the start of display and outputs a time-up signal after a set time, and means for changing the position of the display dot to be displayed and re-displaying it based on the time-up signal. According to the invention, all display dots are turned off for a certain period of time when changing or redisplaying the display.

[Function] In the present invention, the same display dot does not continue to light up, and all display dots light up evenly, and the maintenance and replacement intervals are longer for display elements such as light bulbs that have a breakage life. Therefore, in display elements such as light emitting diodes, where luminous intensity drop and temperature rise are problems, the luminous intensity drop is reduced, the temperature rise is also reduced, and when the display is changed or redisplayed, all display dots turn off, making it easier to see. The abnormal feeling you feel disappears.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 2 is a plan view showing the display surface of the information display device according to the present invention. In the figure, D1 to D64 indicate light emitting diodes, and the finely hatched parts indicate that the light emitting diodes are emitting light, and the display is switched in the order of figure (a) to figure (d), and The figure returns to (a>).

Figure 3 shows the light emitting diodes that emitted light in Figures 2 (a) to (d). In Figure 2 (a) to (d), 17 of the 64 light emitting diodes Each of them emitted light, and looking at Figure 3 shows that 40 of the 64 lights emitted light, and by switching between Figures 2 (a) to (d), the display surface emitted light on average. It shows that In Fig. 2, when (a) to (b) are displayed at the same time, if you look at the light emitting diode D1B at the tip of the arrow display, you will notice that while the display of Fig. 2 (a) and (C) is the same, It emits light, and the lighting rate during the display period is 50%, which is half the time of continuous light emission. Moreover, when looking at the light emitting diode D4, it emits light during the display shown in FIG. 4(c), and the lighting rate during the display period is 25%. Figure (a)~
There is no light emitting diode that emits light continuously during the period (d), which prevents a particular light emitting diode from constantly emitting light, and by appropriately selecting the display switching time, the self-emission of the light emitting diode This shows that it is possible to prevent the temperature rise due to heat generation to some extent, and that the decrease in luminous intensity due to the operating time of the light emitting diode can be relatively reduced. Also, the diagram in Figure 2 <a) →
When changing the display from Figure (b) to Figure (C) to Figure (d), by making the entire display surface turn off as shown in Figure 2 (e), the arrow display appears to have moved. It can also be made invisible. In addition, in FIG. 2, the displayed content is shown as an arrow, but the displayed content is not limited as it is the same with characters.

FIG. 1 is a block circuit diagram showing the configuration of an embodiment of an information display device according to the present invention, and is a circuit diagram specifically realizing the display switching shown in FIG. 2. In the figure, MEMI is a light emitting diode D1 that constitutes the display surface.
This is a storage circuit that stores display designation data that designates which of D64 to emit light or not, and is usually composed of RAM or ROM.

FIG. 4(a) shows the contents of the display designation data stored in the memory circuit MEM1.

rl, , r□ in the display specification data shown in the figure.

The data array in the memory circuit MEMI is arranged in rows 1 to 8 and column 1.
-8, and as shown in FIG. 1, when a pulse is received from the terminal CP1, the terminal O
UT from 8 rows and columns 8 to 8 rows and 1, then from 7 rows and 8 to 7 rows and 1
It outputs serial data from the 1st row and 8th column to the 1st row and 1st column in column order, and the terminal OUT is connected to the serial input terminal Sr of the parallel out shift register SRI with serial in latch. In addition, shift register SR
I is generally commercially available under the format name TC74HC595. Further, the shift register SR1 shifts the data at the eight serial input terminals to the right every time a pulse from the clock input terminal CP is input, and outputs the serial data to the serial output terminal SO. The output terminal SO is connected to the input terminal SI of the next stage shift register SR2, and the shift register SR2 shifts the data at the input terminal SI to the right every time a pulse from the clock input terminal CP is input.

The following is connected up to shift register SR8.

When the shift register SRI receives a latch signal (not shown), it latches the serial data and outputs it to the parallel output terminal Q.
Output to 1 to Q8. Parallel output terminals Q1 to Q8 are connected to light emitting diodes D1 to D1, which constitute the display screen shown in FIG.
The anode of D8 is connected, and the light emitting diodes D1 to D8
The cathodes of each pass through a current detection circuit C8 and are connected to the zero volt line L. shift register SRI
Serial data is input to the parallel output terminals Q1 to Q
At 8! ll! When "1" is output, current flows through the connected light emitting diode, and the light emitting diode emits light. Further, in the current detection circuit C8, specifically, as shown in FIG. 5, the cathode of a light emitting diode is connected to the terminal DI,
The current flowing through the light emitting diode passes from the base B of the transistor TR to the emitter E, becomes a base current, and is sent to the terminal G.
Flows from to zero volt line L. When the base current flows in the transistor TR, it turns on and the collector C becomes the state "0".
Since the collector C is connected to the inverter INV2, the output of the inverter INV2 is connected to the terminal Do.
Outputs state [1j. The terminal DO is the parallel input terminal PI of the shift registers SR9 to 5R18 in FIG.
They are connected to I to PI8, respectively. These shift registers SR9 to 5R18 have parallel input and serial output, and are generally commercially available under the format name TC748C59.
When a latch signal (not shown) is inputted to the data inputted to II to PI8, the data is lied, shifted one bit to the left every time a clock pulse is inputted to the clock input terminal CP2, and outputted to the serial output terminal SO2. Output terminal S
O2 is input to the input terminal IN of the memory circuit MEM2, and the memory circuit MEM2 changes the data of the input terminal IN from the 8th row and 8th column to the 8th row and 1st column, and then from the 7th row and 8th column by inputting a pulse from the terminal CP3. Serial data is stored in order from 7 rows and 1 column to 1 row and 1 column. FIG. 4(b) shows the data. Further, the serial input terminal SI2 of the shift register SR9 is connected to the serial output terminal SO2 of the preceding stage shift register 5RIO. This allows the current flowing through the light emitting diodes D1 to D64 to be detected by the current detection circuit C8.
The shift registers SR9 to 5R16 transfer the detected data as serial data to the memory circuit MEM2,
This constitutes a so-called monitoring circuit that stores the state of the light emitting diode in the memory circuit MEM2. Normally,
Data consistency between the memory circuit MEMI and the memory circuit MEM2 is compared by a CPU (not shown), and an abnormality such as a disconnection of a light emitting diode is detected. In addition, in Fig. 5,
A transistor was used to detect the current of the light emitting diode, but
A photo coupler or the like may also be used. In addition, in FIG. 12, C2 is a counter that counts up in response to a pulse at its terminal CP4.When it counts 55, it sends a signal to terminal O1, when it counts 56, it sends a signal to terminal 02, and when it counts 63, it sends a signal to terminal 03. Then terminal 04
Outputs a signal to each. Terminals 01 to 04 are connected to one input of AND circuits AND1 to AND4, and the other input of AND circuit AND1 is connected to terminal 07 of counter C1.
However, the other input of the AND circuit AND2 is the counter C1.
The other input of the AND circuit AND3 is connected to the terminal 06 of the counter C1, and the other input of the AND circuit AND4 is connected to the terminal 05 of the counter C1. Counter C2 supplies shift registers SR9 to SR5 from memory circuit MEM1 to shift registers SR1 to SR8.
It controls the transfer of data from R16 to the memory circuit MEM2, and when a signal is input to the reset terminal R1, it is reset, the output from the terminals 01 to o4 disappears, the count is reset, and the state! Counter C2 becomes "0"
The output of the AND circuit AND5 is connected to the terminal CP4 of the AND circuit AND5, and one of the inputs of the AND circuit AND5 is connected to the clock pulse generator O8C, and the other is connected to the output of the inverter INVI. The input of the inverter INVI is connected to the output of the OR circuit OR1, and the input of the OR circuit ORI is connected to the outputs of the AND circuits AND1 to AND4. The counter C1 counts cycles upon receiving pulses from the terminal CP5. Terminal 06. Terminal 07. Terminal 08. Signals are output in the order of terminal 05. The output of the OR circuit OR2 is connected to the terminal CP5 of the counter C1, and the output passes through the OR circuit OR3 to the terminal CP5 of the counter C1.
is connected to the reset terminal R1 of. OR circuit OR2
The output terminal 09 of the timer TM is connected to one of the inputs of the timer TM. When a signal is input to the reset terminal R2 of the timer TM, the timer TM is reset to the initial value, and when the set time has elapsed, a signal is output to the terminal 09 to restart the timer TM.

A signal from the terminal T is connected to the other input of the OR circuit OR2, and this signal is connected to the reset terminal R2 of the timer TM. A signal is input to the terminal T when changing the display, and normally the signal is input to the terminal T after data to be displayed is stored in the memory circuit MEM1.

The output of the AND circuit AND5 is connected to the common of the switch SW, and the contact S1 of the switch SW is connected to the shift register SR.
Terminal CP of 1 to SR8 and terminal CP1 of memory circuit MEM1
The contact S2 is connected to the shift register SR9-5R.
It is connected to the terminal CP2 of the memory circuit MEM2 and the terminal CP3 of the memory circuit MEM2. The switch SW performs display and monitoring, and when contact S1 is selected, a display switching operation is performed, and when contact S2 is selected, a monitoring operation is performed. Assuming that a signal is input to terminal T, timer TM and counter C2 are reset, and a signal is output from terminal 05 of counter C1, no signal is output to terminals 01 to 04 of counter C2, so the OR The output of the circuit OR1 is in the state "0" and the output of the inverter INVI is in the state "1". The output pulse of the clock pulse generator O8C passes through the AND circuit AND5, passes through the contact S1 selected from the common of the switch SW, operates the memory circuit MEMI and shift registers SR1 to SR8, and stores the data in the memory circuit MEMI in 8 rows. The data is sequentially sent to shift registers SRI to SR8 starting from the 8th column. The output of the clock pulse generator O8C is also input to the counter C2, so the counter C2 inputs the input of the terminal CP4 to 6
When 4 counts are made, a signal r1. is output. The signal is sent from the AND circuit AND4 to the OR circuit oR1.
The output of the inverter INVI is set to "0". The output of the clock pulse generator O8C is an AND circuit AND
5, so the memory circuit MEMI is 64.
Since it outputs data of the number of shift registers SR
The data in I to SR8 is in the state shown in Fig. 6 (C> Fig. 2 (g), Fig. 1 (k), ... Fig. (0)), and its output is sent to terminals Q1 to Q8 of shift registers SRI to SR8. The current is output and flows through the light emitting diodes D1 to D64, causing them to emit light.
The display shown in FIG. 2(a) will be displayed. At this time,
Shift registers SR8 to 5R16 are shown in the diagram (O) in FIG.
The state will be as shown in Figure 1 (a), Figure 1 (e), and Figure 1 (m). Next, the case of monitoring will be described. When the contact S2 of the switch SW is selected and a monitoring command signal in the state "1" is input to the terminal W, the signal passes through the OR circuit OR3 and resets the counter C2. The output pulse of the clock pulse generator O8C passes through the contact S2 of the switch SW, operates the shift registers SR9 to 5R16 and the memory circuit MEM2, and the counter C2 transfers data up to 64.
The data in the shift registers SR9 to 5R16 are transferred to the memory circuit MEM2 in the diagrams in FIG. Then, when the timer TM times up and outputs a signal to terminal 09, the signal is output to the OR circuit O.
It passes through R2, advances the counter C1 by one, outputs a signal to the terminal 06, and passes through the OR circuit OR3, resetting the counter C2. The output of the clock pulse generator O8C is sent to an AND circuit AND5. It passes through the contact S1 of the switch SW, and is connected to the shift registers SR1 to SR8 and the memory circuit ME.
Run MI. When the count number of the counter C2 reaches 63, a signal "1" is output from the terminal 03, so the output of the clock pulse generator O8C is output from the AND circuit AND.
It can be stopped at 5. At this time, the data transfer from the memory circuit MEM1 to the shift registers SR1 to SR8 is up to 63, so the state of the shift registers SR1 to SR8 is 6th.
Figure (d) Figure 1 (h> Figure 2 (1)...As shown in Figure (p), the data is shifted one dot to the left compared to Figures (C) to (0), and the data is not driven. Light emitting diode D
The light emitting states of 1 to D64 are as shown in FIG. 2(b), and compared to FIG. 2(a), the arrows have shifted one dot to the left. Next, regarding monitoring, when the contact S2 of the switch SW is selected and the monitoring command signal "1" is input to the terminal W, the data from the shift registers SR1 to 5R16 are output to the terminal 03 of the counter C2. That is, the output of the clock pulse generator O8C is transferred to the memory circuit MEM2 until 63 outputs are output. shift register S
The data status of R9 to 5R16 is shown in Figure 6 (b) 2.
Figure (f) 1 Figure (j)... Figure (n>), so
When these are transferred to the memory circuit MEM2 while being shifted to the left, the memory circuit MEM2 has the same arrangement and the same data. Next, when the timer TM times up, the display state changes to the state shown in FIG. 2(c), based on the above explanation.
Then, when the timer TM times up, as shown in FIG.
), and then when the timer TM times up, the state shown in FIG. 2(a) occurs. Even if the display changes like this, the memory circuit MEM1 and the memory circuit MEM2
Since the data arrangement and state match, if the circuit is operating normally, no mismatch will occur even if both data are compared. However, due to some abnormality, the shift register does not transfer, or the light emitting diodes D1 to D
64 is broken, the mismatch in that part can be detected and maintenance and replacement can be performed. Also, in Figure 1,
Monomulti MM is connected to the output of OR circuit OR2, and when it receives the signal, it outputs a signal in state "1" to inverter INV3 for a certain period of time. The output of the inverter INVB is in contact with the output control terminals OE of the shift registers SRI to SR8, and the shift registers SRI to SR8 do not output signals to the terminals Q1 to Q8 when the output control terminal OE is "0". While the signal is being output from the monomulti MM, the terminals Q1 to SR8 of shift registers SRI to SR8
The light emitting diodes D] to D8 are prevented from emitting light by not outputting a signal from Q8. That is, the display screen is turned off for a certain period of time when switching the display and when switching the display position when the display time exceeds a certain period of time.

With this configuration, a shift register is used as a means for transferring one display command data from the storage circuit to the light emitting diode drive circuit, and the display position can be easily changed by controlling the number of data transfers.

In addition, when the monitoring data indicating the light emitting state of the light emitting diode is transferred to the storage circuit using a shift register, the number of transfers for display and the number of transfers for monitoring are the same by shifting the data in the opposite direction to that for display. By doing this, the arrangement of display command data and the arrangement of monitoring data can be made the same,
This provides an advantage in that the display command data and the monitoring data can be compared easily.

In the above-described embodiment, data transfer was explained using a shift register, but addresses may be used, or parallel data may be transferred. Furthermore, although switching between display and monitoring has been described using a switch SW, it goes without saying that it can be constructed using a semiconductor logic circuit. Furthermore, although the switching of the display position has been described in terms of four positions, it goes without saying that fMIN is not included in that number. Furthermore, although the explanation has been given in which the display position is switched by hardware using a counter and a shift register, it goes without saying that the display can also be switched by software using the CPU.

[Effects of the Invention] As explained above, according to the present invention, the display position on the display screen is changed when the display is changed and at regular intervals, so that when the display pattern is fixed, a specific display dot is Since continuous lighting is no longer required, the deterioration of luminous intensity due to temperature rise is significantly reduced, the life of the display element is extended, and an extremely excellent effect is obtained in that an information display device with high quality and reliability can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing the configuration of an embodiment of the information display device according to the present invention, FIGS. 2 and 3 are plan views showing the display surface of the information display device according to the present invention, and FIG. 5 is a circuit diagram showing the configuration of the current detection circuit, FIG. 6 is a diagram showing the storage state of the shift register, and FIG. 7 is a diagram showing the luminous intensity drop per operating time of the light emitting diode. Figure 8 is a plan view showing a display example of a graphic display board, Figure 9 is a diagram showing the ambient temperature versus luminous intensity characteristics of a light emitting diode, and Figure 1O is a diagram showing the absolute maximum forward current reduction characteristic of a light emitting diode. It is a diagram. D1-D64 --- Light emitting diode, MEMl, ME
M2...Memory circuit, SRI-5RI8...Shift register, Prl-P118...Parallel input terminal, Q1-Q8...Parallel output terminal, C8...
Current detection circuit, ■NV1 to INV3... Inverter, AND1 to AND5... AND circuit, C1, C2
... Counter, O20 ... Clock pulse generator, OR1-OR3 ... OR circuit, SW ... Switch, TM ... Timer, MM ... Monomulti.

Claims (3)

[Claims] (1) Displayed when changing the display in an information display device in which a self-luminous display element is used as a display dot, the display dots are arranged in a matrix in the vertical and horizontal directions, the display dots are made to emit light, and the display is displayed in dots. 1. An information display device comprising means for changing a display dot position at which a display starts. (2) In claim 1, a timer is provided which starts counting from the start of the display and outputs a time-up signal after a set time; An information display device characterized in that it is provided with means for re-timing. (3) In claim 1, display designation data specifying lighting or non-lighting for each of the display dots is output, and based on the display data, the display dots are turned on or off and displayed, and each display dot is turned on. , a monitoring circuit is provided that returns display state data indicating the state of lights out, and compares the display designation data, and when the display designation data indicates that the display dots are changed to indicate lighting or lights out, the display state is changed. An information display device characterized in that the display dot position of the data is changed to match the display dot position specified by the display specification data, and the data is returned.