CN216902208U

CN216902208U - Six-stroke display 6 and 9 common-cathode seven-segment digital tube display system

Info

Publication number: CN216902208U
Application number: CN202123028708.2U
Authority: CN
Inventors: 崔建国; 宁永香; 崔燚
Original assignee: Shanxi Institute of Technology
Current assignee: Shanxi Institute of Technology
Priority date: 2021-12-06
Filing date: 2021-12-06
Publication date: 2022-07-05
Anticipated expiration: 2031-12-06

Abstract

The utility model discloses a common cathode seven-segment nixie tube display system with six-stroke displays 6 and 9, 4-bit BCD codes D3, D2, D1 and D0 are respectively connected with corresponding pins D, C, B, A of 74LS48, output pins a, b, c, D, e, f and g of 74LS48 are respectively connected with corresponding pins a, b, c, D, e, f and g of BS201A, pin A is connected with the base of T1 through a resistor R1, the emitter of T1 is connected with the ground, the collector of T1 is connected with the base of T2 through a resistor R3, the collector of T2 is connected with pin a, the emitter of T2 is connected with a +5V power supply circuit, pin D is connected with the base of T3 through a resistor R2, the emitter of T3 is connected with the ground, the collector of T3 is connected with the base of T8 through a resistor R4, the collector of T4 is connected with pin D, the emitter of T5 is connected with a +5V power supply circuit, and the digital number of BS A is improved.

Description

Six-stroke display 6 and 9 common-cathode seven-segment digital tube display system

Technical Field

The utility model relates to a technology for improving seven-segment nixie tube display, in particular to a common cathode seven-segment nixie tube display system which can be designed to display 6 and 9 by six strokes on the basis of an original seven-segment display circuit.

Background

In digital systems, people often adopt a simple digital display circuit to directly display the measurement or operation result by a nixie tube (LED nixie tube) so as to monitor the working condition of the system.

The LED nixie tube is divided into a seven-segment nixie tube and an eight-segment nixie tube according to the number of segments, the seven-segment nixie tube is one less light-emitting diode unit (namely one less decimal point DP display) than the eight-segment nixie tube, and the seven-segment nixie tube is divided into a common anode nixie tube and a common cathode nixie tube according to the connection mode of the light-emitting diode units.

The common anode nixie tube is a nixie tube which connects anodes of all light-emitting diodes together to form a common anode (COM), when the common anode nixie tube is applied, the common anode COM is connected to +5V, when a cathode of a light-emitting diode in a certain field is at a low level, a corresponding field is lightened, and when a cathode of a certain field is at a high level, a corresponding field is not lightened.

The common cathode nixie tube is a nixie tube which connects cathodes of all light-emitting diodes together to form a common Cathode (COM), when the common cathode nixie tube is applied, the common cathode COM is connected to a ground wire GND, when an anode of a light-emitting diode in a certain field is in a high level, a corresponding field is lightened, and when an anode of a certain field is in a low level, a corresponding field is not lightened.

However, in the commonly designed seven-segment digital display system, no matter the TTL decoding/driving circuit or the CMOS decoding/driving circuit is adopted, the display forms of the numbers 6 and 9 are not satisfactory, that is, one bar is less for displaying 6 and 9, one bar is less for displaying the upper side of 6, and one bar is less for displaying the lower side of 9, that is, 5-stroke display 6 and 9, which is determined in the conventional BCD code seven-segment display decoding/driving chip circuit and generally cannot be modified.

A common cathode seven-segment digital tube display system capable of displaying 6 and 9 by six strokes can be designed on the basis of the original seven-segment display circuit, and the horizontal lines which are lacked by the traditional 6 and 9 5-stroke display are supplemented, so that a satisfactory display effect is achieved.

Disclosure of Invention

The utility model aims to solve the technical problem of providing a technology which has simple structure, low manufacturing cost and reliable use and can improve the display of a seven-segment digital tube.

In order to achieve the above purpose, the utility model provides a common cathode seven-segment nixie tube display system of six-stroke display 6 and 9, which comprises a seven-segment nixie tube display decoding/driver circuit, a 7-segment LED nixie tube circuit, a switch circuit externally connected with a pin a, a switch circuit externally connected with a pin D, a +5V power supply circuit, 4-bit BCD codes D3, D2, D1 and D0 which are respectively connected with corresponding pins D, C, B, A of the seven-segment nixie tube display decoding/driver circuit 74LS48, output pins a, b, c, D, e, f and g of 74LS48 which are respectively connected with corresponding pins a, b, c, D, e, f and g of the seven-segment nixie tube circuit BS201A, a resistor R1, a transistor T1, a resistor R3 and a transistor T2 which form the switch circuit externally connected with the pin a, a resistor R2, a transistor T3, a resistor R4 and a transistor T4 which form the switch circuit externally connected with the pin D, pin a of 74LS48 is connected to the base of transistor T1 through resistor R1, the emitter of transistor T1 is operatively connected, the collector of transistor T1 is connected to the base of transistor T2 through resistor R3, the collector of transistor T2 is connected to output pin a of 74LS48, the emitter of transistor T2 is connected to the +5V supply circuit, pin D of 74LS48 is connected to the base of transistor T3 through resistor R2, the emitter of transistor T3 is operatively connected, the collector of transistor T3 is connected to the base of transistor T4 through resistor R4, the collector of transistor T4 is connected to output pin D of 74LS48, the emitter of transistor T4 is connected to the +5V supply circuit, and the 7-segment LED nixie circuit BS201A shows improved numbers.

Drawings

FIG. 1, FIG. 2, FIG. 3, and FIG. 4 are provided to provide a further understanding of the present invention and form a part of this application, and FIG. 1 is a schematic diagram of a conventional seven-segment digital display system; FIG. 2 is a display diagram of conventional display systems 6 and 9; FIG. 3 is a schematic diagram of an improved common cathode 7-segment nixie tube display system; fig. 4 is a diagram of the effect of the improved 7-segment digital display system.

Detailed Description

The seven-segment digital decoding display system principle generally adopts a medium-scale BCD code seven-segment display decoding/driver which can provide larger current to flow through a light-emitting diode, and the decoding/driver ICs can be divided into: the CMOS is a field effect transistor configuration (unipolar circuit), and the TTL is a bipolar transistor configuration (bipolar circuit).

TTL models are 7446, 7447, 7448 and 7449, CMOS models are 4511 and the like, wherein 7446 and 7447 must use seven-segment displays with common anode, and 7448, 7449 and 4511 use seven-segment displays with common cathode.

The seven-segment digital decoding display system widely adopted in the industry only needs to connect the strip-shaped light-emitting diodes introduced above according to a common cathode (negative electrode) or common anode (positive electrode) method to form a 8 character, then uses the other electrode of the light-emitting diodes as a pen segment electrode to form an LED nixie tube, and if the light-emitting diodes on certain pen segments are made to emit light according to the regulations, a series of numbers from 0 to 9 can be displayed.

Therefore, no matter the common cathode or common anode nixie tube, a BCD seven-segment display decoding/driver circuit is usually adopted to complete the driving of the nixie tube, fig. 1 is a schematic diagram of a seven-segment digital display system commonly used in the industry, and the model of the BCD decoding driver is 74LS48 and is a TTL device; the nixie tube is BS201A, which is a seven-segment common cathode semiconductor nixie tube.

The 74LS48 is a seven-segment display decoding/driving device of a medium-scale BCD code, can provide a large source current to flow through a light-emitting diode, a decoding function table of 74LS48 is listed in Table 1, four input signals DCBA correspond to four-bit binary code input, 7 output signals a-g correspond to seven-segment character patterns, and when the decoding output is 1, corresponding fields of a fluorescent nixie tube are lightened.

For example, when DCBA =0001, since the decoder outputs b and c are 1, the b-segment and c-segment are lit to display the numeral 1; when DCBA =0101, since the decoder outputs a, c, d, f, and g are 1, the corresponding segments are lit up, and numeral 5 is displayed.

Table 174 LS48 logic function table

Based on the above theory, the display form of the seven-segment digital decoding display system widely adopted in the industry is not satisfactory when displaying the numbers "6" and "9", i.e. one less horizontal line is displayed when displaying 6 and 9, 5 strokes are displayed, one less horizontal line is displayed on the upper surface when displaying 6, and one less horizontal line is displayed on the lower surface when displaying 9.

The specific reason can be seen from table 1, when 6 is displayed, the outputs of c, d, e, f and g of the decoder 74LS48 are 1, and the output of a is 0, so that only 5 strokes corresponding to c, d, e, f and g are lit, the stroke a is not lit, and the top of 6 is displayed with one bar less.

Similarly, when displaying 9, the outputs a, b, c, f and g of the decoder 74LS48 are 1, and the output d is 0, so that only 5 strokes corresponding to a, b, c, f and g are lit, the stroke d is not lit, and the lowest side of the display 9 is at least one horizontal line.

Although the display mode does not affect the work, the display mode is not satisfactory in all, the display of the counter liquid crystal screen 6 and 9 has no defect of one less horizontal line, the later is satisfactory, whether the missing picture horizontal line in the display 6 or 9 can be completed on the basis of a traditional display system, and the answer is right.

Since the deficiency of the conventional digital display system for displaying 6 or 9 is due to the fact that the a-segment stroke or the d-segment stroke is not lighted, if the method is to light the a-segment stroke or the d-segment stroke when the input end BCD code DCBA =0110 (display 6) or DCBA =1001 (display 9) of the decoder 74LS48, the deficiency of the conventional display system is not compensated, and the a-point output or the d-point output of the decoder is actually made to be "1" at this time (the conventional display system is made to be 0 at this time at the a-point and the d-point).

This idea, which is impossible to realize by relying entirely on the conventional display system, can be implemented by connecting an external switch circuit to the corresponding output terminal a or d of the decoding chip 74LS48, wherein the input terminal of the switch circuit is connected to +5V, and the output terminal is connected to a point a or d, and when it is necessary to display other numbers except 6 and 9, the external switch circuit must be equivalent to completely invalid, i.e. the external switch circuit has no relation to displaying 0, 1, 2, 3, 4, 5, 7, 8 numbers at all.

Once 6 or 9 needs to be displayed, the external circuit is conducted, so that the end a or the end d is '1', the stroke of the section a or the stroke of the section d is lightened, and the complete six strokes 9 or 6 are displayed.

The problem is that the external circuit controls the signal from where, if the external circuit directly supplies power from V_CCIf the control signals are provided from the output ends a, b, c, d, e, f and g of the decoder, the logic relationship is seemingly complicated, and the display of other strokes is also influenced.

Which may be provided from the input of decoder 74LS48, i.e., the binary-decimal code (BCD code) DCBA, the question is how to get a suitable code from the DCBA to drive the two switching circuits, and when 6 or 9 is displayed, a "1" or "0" must be applied to the enable of the corresponding switching circuit, the switch is turned on, and the a-point or d-point of the switching circuit is set to "1", so that the a-segment or d-segment stroke is lit to display the complete six-stroke 6 or 9.

When displaying other numbers except 6 or 9, if the display of the number does not need the lighting of the a-stroke or the d-stroke, for example, the display of 1, 4 does not need the lighting of the a-stroke or the d-stroke, then the control signals '1' or '0' can not be provided for the control poles of the two switch circuits, otherwise the display is disordered;

if the a-stroke or d-stroke is required to be lighted when other numbers than 6 and 9 are displayed, such as 0, 2, 3, 5, 7 and 8, the logic level of the a-stroke or d-stroke is 1 even if no switch circuit exists at the moment, the a-stroke or d-stroke can be lighted by itself, and if the switch circuit exists at the moment and an effective control signal is sent, the display of 0, 2, 3, 5, 7 and 8 is not influenced.

The above idea of displaying only six strokes 6 or 9, that is, when displaying 6 or 9, to make point a or point d be "1", but not to affect the display of other numbers, it can be seen from the 74LS48 logic function table (truth table) of table 1 that when the displayed number is 6, C and B in the BCD input code DCBA are "1", and it seems that one "1" can be randomly selected from C and B to control the lighting of segment a.

However, by carefully observing the truth table of table 1, it can be found that this "1" of C cannot be used, because it can be seen from the other codes of this column of C of the truth table that the other number 4 of column C also has a "1", but the 7-segment nixie tube of number 4 displays no a segment, if the point C of the decoder input code is connected to the control terminal of the switch circuit externally connected to the point a of the decoder output signal, it will result in a perfect 6-stroke display when displaying 6, but when displaying 4, since C is now "1", but display 4 does not need a segment, the "1" of C drives a point a to be "1", and number 4 displays a conventional "9", which shows an error.

Therefore, the control terminal of the external switch circuit at the point a cannot be connected with the point C.

If the end B of the BCD input code is connected with the control end of the external switch circuit for outputting the a point of the signal, because other numbers corresponding to the row of the B with 1 are 2, 3 and 7 in the column of the B, 7 segments of the numbers display all strokes of a segment, namely the a point signal is originally 1 when the 2, 3 and 7 are displayed, the number 6 display of the 6 strokes can be perfectly realized by connecting the end B with the control end of the external switch circuit for a point, and the display of other numbers except 6 is not influenced.

Referring now to the display of the number 9, it can be seen from the truth table in table 1 that the numbers 9 in the columns of the decoder BCD code D, A all have "1", and the numbers 1, 3, 5, and 7 all have "1" except 9 in the column a, and referring to the above analysis, although the numbers 3, 5, and 7 need to be lit by d-segment strokes when displaying, the number 1 does not need to be lit by d-segment strokes when displaying, so if the point a at the input end of the decoder is connected to the control end of the external switch circuit at the point d of the decoder, the display of the number 1 will be wrong.

And looking at the column of the BCD code D of the decoder, except that the number 9 has '1', only the number 8 also has '1', but the number 8 needs D sections of strokes to be lightened when displayed, so that the D point at the input end of the decoder is connected with the control end of an external switch circuit at the D point of the output end, and the display of the number 9 of 6 strokes can be perfectly realized.

From the above analysis, a schematic diagram of an improved common-cathode 7-segment nixie tube display system shown in fig. 3 can be drawn, wherein the circuit includes a seven-segment display decoding/driver circuit, a 7-segment LED nixie tube circuit, a switch circuit externally connected to a point a, a switch circuit externally connected to a point d, and a +5V power supply circuit.

The model of the decoding/driver is 74LS48, the decoding/driver is a seven-segment display decoding/driver of a medium-scale BCD code, 4 input signals DCBA correspond to 4-bit binary code input, 7 output signals a, b, c, d, e, f and g are effective in high level, and larger source current can be provided.

The model of the nixie tube circuit is BS201A, a common cathode circuit is adopted, so the outputs a-g of the decoder 74LS48 are respectively added to 7 anodes of the nixie tube, but only the high-level diodes on the anodes are in light-emitting conduction, and corresponding decimal numbers in 0-9 are displayed.

The switch circuit externally connected with the point a is composed of a resistor R₁Transistor T₁、T₂Resistance R₃Constitution T₁、T₂For NPN, PNP complementary mating pipes, i.e. T₁Is an NPN tube, T₂Is a matched PNP pipe; the switch circuit externally connected with the point d is composed of a resistor R₂Transistor T₃、T₄Resistance R₄Constitution T₃、T₄Also NPN, PNP complementary paired tubes, i.e. T₃Is an NPN tube, T₄Are paired PNP tubes.

Transistor T₁、T₂、T₃、T₄The selection of the transistors is simple, the type of the transistor is determined according to the working current of the nixie tube, the average current of each section of the BS201A nixie tube is 3mA, so that common NPN tubes 9013, 9014, 8050 and 2N5551 can be selected for the transistor, PNP tubes 9012, 9015, 8550 and 2N5401 can be selected for the transistor, 2N5551 is selected for the NPN tubes, and 2N5401 is selected for the PNP tubes.

Firstly, arranging a connection line between the decoder and the nixie tube according to a normal working principle, then connecting a point A at the input end of the decoder with a point a through an external switch circuit of the point a according to the diagram shown in fig. 3, and similarly, connecting a point D with a point D through an external switch circuit of the point D.

Then the transistor T is connected₁、T₃Is connected to the operating ground, T₂、T₄Is connected to +5V supply.

The actual effect diagram of the circuit of fig. 3 enables the display of 6 and 9 of six strokes as shown in fig. 4.

The display method has the advantages that the logical relation between the input end and the output end of the decoder is skillfully utilized, the six-stroke display of the numbers 6 and 9 is realized by utilizing an external circuit, and the display capability of the 7-segment nixie tube is perfectly improved.

Claims

1. A six-stroke display 6 and 9 common cathode seven-segment digital tube display system is characterized in that: the common-cathode seven-segment nixie tube display system comprises a seven-segment nixie tube display decoding/driver circuit, a seven-segment LED nixie tube circuit, a switch circuit externally connected with a pin a, a switch circuit externally connected with a pin D, a +5V power supply circuit, 4-bit BCD codes D3, D2, D1 and D0 which are respectively connected with corresponding pins D, C, B, A of the seven-segment nixie tube display decoding/driver circuit 74LS48, output pins a, b, c, D, e, f and g of the 74LS48 are respectively connected with corresponding pins a, b, c, D, e, f and g of the seven-segment LED nixie tube circuit BS201A, a resistor R1, a transistor T1, a resistor R3 and a transistor T2 form the switch circuit externally connected with the pin a, a resistor R2, a transistor T3, a resistor R4 and a transistor T4 form the switch circuit externally connected with the pin D, a pin A of the 74LS48 is connected with a base of the transistor T1 through a resistor R1, the emitter connection of transistor T1 is operative, the collector of transistor T1 is connected to the base of transistor T2 through resistor R3, the collector of transistor T2 is connected to output pin a of 74LS48, the emitter of transistor T2 is connected to said +5V supply circuit, pin D of 74LS48 is connected to the base of transistor T3 through resistor R2, the emitter of transistor T3 is connected to operative ground, the collector of transistor T3 is connected to the base of transistor T4 through resistor R4, the collector of transistor T4 is connected to output pin D of 74LS48, the emitter of transistor T4 is connected to said +5V supply circuit, said seven-segment LED nixie circuit BS201A shows improved numbers.