JPS5937822Y2 - Display drive circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a display drive circuit for a display element formed from a plurality of segments.

In general, display elements used in display devices such as electronic computers include, for example, light emitting diode display elements (hereinafter abbreviated as LED display elements) as shown in FIG.

This LED display element has 7 segments for numerical display)
2 of "O" to "9" and "0." to "9." fit from a-g and one segment D-P for decimal point display
0 types of content can be displayed.

Conventionally, when such an LED display element is used, not only numerical data is displayed, but also a predetermined symbol may be indirectly displayed by the same type of display content as that of the numerical data.

However, this makes it difficult to distinguish between numbers and symbols, so incorrect information may be conveyed to the operator.

This idea was made in view of the above circumstances,
The purpose of this is to have a simple configuration that can output segment drive signals for displaying numbers on display elements with a minimum number of human input signals, and also output segment drive signals for displaying symbols. The present invention provides an extremely practical display driving circuit that can perform the following functions.

An embodiment of this invention will be described below with reference to the drawings.

1 is a first latch driver having a decoding function, and has input terminals IA, IB, IC, and ID.

IL-P and output terminals 1a, lb, lc, ld.

It is equipped with le, If, and 1g.

The input terminals IA, IB, IC, and ID are supplied with encoded 4-bit human input signals A, B, C, and D corresponding to numerical data from a control section (not shown), respectively. It has become.

Further, the input terminal IL-P is supplied with a latch pulse LP from the control section.

Therefore, the driver 1 receives the human input signals A, B,
Based on C, D, predetermined output terminals 1a, lb,
lc, ld, le.

Signals are output to If and Ig.

In this case, output terminals 1a, lb, lc, l
d, le.

The signals output from If and Ig are LE in FIG.
D display element segments a, b, c, d.

Segment drive signals Sa, Sb, Sc, Sd, Se, Sf, corresponding to e, f, g, respectively
Sg, and its state is maintained from the time the latch pulse LP is supplied until the next latch pulse is supplied.

In this case, the segment drive signal Sf output from the output terminal 1f is supplied to one input terminal of the OR circuit 2.

Further, 1. The segment drive signal Sg outputted from the output terminal 1g is supplied to one input terminal of the OR circuit 3.

Note that 1,81) are 4-bit human input signals A and B corresponding to numerical data.

This shows the correspondence between C and D, the segment drive signals based on them, and the display contents.
Shown in the figure.

As shown in this table, driver 1 receives human power signal A,
Output is prohibited when the contents of B, C, and D reach 2 digits.

On the other hand, 4 has a decoding function and input terminals 4A and 4B.
, 4C, 4D, 4L-P and output terminals 4a, 4b, 4
A second latch driver having latch elements c, 4d, 4e, 4f, and 4g performs exactly the same operation as driver 1 described above.

The input signal A is input to the input terminals 4A and 4B of this driver 4.

B is supplied respectively.

Furthermore, input terminals 4C and 4D of the driver 4 are supplied with NAND outputs of the input signals C and D via a NAND circuit 5.

In this way, by supplying the human power signals C and D to the driver 4 via the NAND circuit 5, the human power signals A,
B.

When the content numbers (numeric data) of C and D become 2 digits,
In other words, when the driver 1 output is prohibited, the content of the human input signal to the driver 4 is set to one digit.

That is, this makes the output of the driver 4 valid.

On the contrary, human power signal A. When the contents of B, C, and D are 1 digit and the output of driver 1 is enabled, the contents of the input signal to driver 4 become 2 digits by the NAND circuit 5, and the output of driver 4 is thereby prohibited. It has become so.

The signals output from the output terminal 4c of the driver 4 are designed to be segment drive signals so and p for the segments DP of the LED display element.

Furthermore, the signal output from the output terminal 4f of the driver 4 is supplied to the other input terminal of the OR circuit 2 as a segment drive signal Sf for the segment f of the LED display element.

Further, a signal outputted from an output terminal 4g of the driver 4 is supplied to the other input terminal of the OR circuit 3 as a segment drive signal Sg for the segment g of the LED display element.

Therefore, in the display drive circuit configured as described above, the 4-bit human input signals A, B,
The following table 2) summarizes the correspondence between C and D, segment drive signals based on them, and display contents.

In this case, the display contents (symbols) obtained by the driver 4 and the NAND circuit 5 are shown in FIG.

Next, the operation in the above configuration will be explained.

This case will be explained with reference to the time chart shown in FIG.

First, for example, a human signal A corresponding to numerical data "0"
, B, C, and D are about to be supplied to driver 1.

In other words, human signals A and B. C and D are each logical v
When the tO)m signal is supplied, the latch pulse LP is supplied, so that the segment drive signals Sa, Sb, Sc, Sd,
Se and Sf are output and their states are maintained.

Thus, the number "0" is displayed on the LED display element.

At this time, the human input signals C and D become logic N111 signals by the NAND circuit 5, and the input terminals 4C and 4 of the driver 4
Supplied to D.

Therefore, the content of the human input signal in the driver 4 corresponds to the numerical data "12", and the output of the driver 4 is thereby prohibited.

Afterwards, for example, if human input signals A, B, C, and D corresponding to the numerical data "15" are supplied to the driver 1, in other words, are the human input signals A, B, C, and D respectively logical? +141 signal, latch pulse L-
By supplying P, the holding output of the driver 1 is released.

In other words, the display of the number "0" on the LED display element is canceled.

At this time, since the contents of the human input signals A, B, C, and D correspond to the numerical data "15", the driver 1
output is prohibited.

Then, the human input signals C and D are logically processed by the NAND circuit 5!
f OIf signal becomes input terminal 4C, 4 of driver 4
Supplied to D.

Therefore, the human power signal in the driver 4 corresponds to the numerical data "3", so that the segment drive signals Sg, So
, p are output and their states are maintained.

That is, the symbol shown by ■ in FIG. 4 is displayed on the LED display element.

In this way, although it has a relatively simple configuration,
Five types of symbols can be displayed, including the number "9" and a blank.

Note that the output format of the drivers 1 and 4 in the above embodiment is one for current outflow if the LED display element is a common cathode type, and one for current inflow if the LED display element is a common anode type. use something

This invention is not limited to the above embodiments, but can be modified in various ways without changing the gist of the invention.

As described above, according to this invention, with the above-described configuration, the first driver for displaying numbers is operated based on the encoded multi-bit human input signal corresponding to the numerical data, and furthermore, the content of the human input signal is When the output of the first driver is prohibited due to a predetermined value or more, the content of the human input signal is converted to a predetermined value or less and the second driver for symbol display is operated, so the configuration is simple. However, it is possible to output segment drive signals for displaying numbers on the display element with a minimum number of human input signals, and
An extremely practical display drive circuit that can also output segment drive signals for symbol display can be provided.

[Brief explanation of drawings]

Fig. 1 is an external view of an LED display element, Fig. 2 is a configuration diagram showing an embodiment of this invention, and Fig. 3 is an LED according to the same embodiment.
FIG. 4 is a state diagram showing the numerical display of the display element, FIG. 4 is a state diagram showing the symbol display of the LED display element according to the same embodiment, and FIG. 5 is a time chart for explaining the operation of the same embodiment. 1...First driver (latch driver with decoding function), 2, 3...OR circuit, 4...
. . . 2nd driver (latch driver with decoding function), 5 . . . NAND circuit.

Claims (1)

[Scope of utility model registration request] In a display device equipped with a display element made up of a plurality of segments, a plurality of coded pips I corresponding to numerical data is used.
- a first driver that outputs a drive signal for displaying numbers for a predetermined segment among the segments based on the human power signal, and prohibits the output when the content of the human power signal exceeds a predetermined value; A logic circuit that converts the content of the human power signal to a predetermined value or less in response to output prohibition of the driver, and a drive signal for symbol display for each of the segments based on the human power signal supplied via this logic circuit. A display drive circuit comprising: a second driver.