Scanning drive circuit of high-voltage digital electron tube, circuit board and electronic clock

Abstract

The utility model provides a scan drive circuit, circuit board and electronic clock of high voltage digital electron tube, scan drive circuit includes controller, anode drive circuit, cathode drive circuit, anode drive circuit includes a plurality of pairs of first switch piece, the output terminal of first switch piece is connected with electron tube anode one to one correspondence, cathode drive circuit is connected with cathode drive circuit. The control end of the first switch piece is connected with the controller, the input end of the first switch piece is connected with the driving power supply, the cathode driving circuit comprises a plurality of second switch pieces, and the same numbers of the electronic tubes are connected to one electrode end of the same second switch piece; the control ends of the second switch pieces are connected with the controller, and the other electrode ends of the second switch pieces are all grounded. The number of occupied IO ports of the control mainboard is effectively reduced, and a high-voltage-resistant serial-to-parallel chip or a high-voltage-resistant triode array chip does not need to be used, so that the cost is effectively controlled.

Description

Technical Field

[0001] This utility model relates to the field of electronic technology, and in particular to a scanning drive circuit, circuit board and electronic clock for a high-voltage digital electron tube. Background Technology

[0002] Currently, common neodymium tube (high-voltage digital tube) driving solutions on the market have many limitations. Taking a common display module composed of four neodymium tubes as an example, the A terminal of each neodymium tube serves as the power supply anode, and is usually powered by a uniform stable signal (such as VH1). When controlling each neodymium tube to display a specific number or symbol, it is necessary to independently control the 0-9 digit positions and the two decimal points of each neodymium tube. For example, when lighting the first neodymium tube to display the number 9, the transistor corresponding to the number 9 needs to be turned on. In this scenario with four neodymium tubes, considering only the basic requirement of lighting the numbers, 40 transistors (4 tubes * 10 digits) are needed to control the display of each number. However, in actual circuit design, the controller on the general circuit board cannot provide so many I / Os to directly control these transistors. To solve this problem, two common driving solutions are currently mainly used.

[0003] One approach is to use serial-to-parallel converter chips, such as the 74HC595. However, when this approach is applied to complex scenarios such as those involving four glow discharge tubes, if a combination of high-voltage transistors and 74HC595s is used, typically eight 74HC595s and forty high-voltage transistors are required. This results in a large circuit size, increases circuit area and production costs, and is not conducive to large-scale mass production.

[0004] Another approach is to use serial-to-parallel converter chips with high voltage withstand capability (such as high-voltage Darlington integrated chips like HV57708 / HV5812 / 74141 dedicated driver chip for Glow tubes) to achieve static driving of the Glow tube. However, these integrated chips are very expensive, limiting their widespread application in actual products.

[0005] In summary, existing glow discharge tube driving solutions have significant shortcomings in terms of cost, circuit size, and mass production difficulty, making it difficult to meet the market's demand for high-quality, low-cost glow discharge tube display technology. Utility Model Content

[0006] To address the aforementioned issues, the purpose of this invention is to provide a scanning drive circuit for high-voltage digital vacuum tubes. The controller controls the first switch to select the vacuum tube, and the controller controls the second switch to select the illuminated number. The vacuum tube is driven through a row and column scanning method, thus solving the problems of excessive occupancy of control motherboard I / O ports or excessive cost in traditional high-voltage digital vacuum tube driving.

[0007] This utility model is achieved through the following technical solution:

[0008] A scanning drive circuit for a high-voltage digital vacuum tube includes:

[0009] Controller;

[0010] An anode driving circuit includes a plurality of first switching elements, the output terminals of the first switching elements being connected one-to-one with the anodes of the electron tube, the control terminals of the first switching elements being connected to the controller, and the input terminals of the first switching elements being connected to the driving power supply.

[0011] A cathode driving circuit includes several second switching devices, with the same number of the electron tubes connected to one terminal of the same second switching device; the control terminals of the second switching devices are respectively connected to the controller, and the other terminals of the several second switching devices are all grounded.

[0012] Furthermore, a Zener diode is connected between one terminal and the other terminal of the second switching element, and the Zener diode corresponds one-to-one with the second switching element; wherein, the anode of the Zener diode is connected to the other terminal of the second switching element.

[0013] Furthermore, it also includes a power supply circuit, which includes a flyback circuit or a boost circuit. The output terminal of the power supply circuit is grounded through a capacitor, which is a high-voltage electrolytic capacitor or a solid-state capacitor.

[0014] Furthermore, the driving power supply voltage output by the power supply circuit is 140V to 250V.

[0015] Furthermore, a current-limiting resistor is also provided between the first switching element and the anode of the electron tube.

[0016] Furthermore, the first switching device includes a first transistor and a second transistor. The base of the first transistor is connected to the controller. The emitter of the first transistor is grounded, and the collector is connected to the base of the second transistor. The collector of the second transistor is connected to the power supply, and the emitter of the second transistor is connected to the anode of the electron tube. A pull-up resistor is also connected in series between the collectors of the first transistor and the second transistor.

[0017] Furthermore, the second switching device is an NPN transistor, the base of the second switching device is connected to the controller, the collector of the second switching device is connected to the cathode of the electron tube, and the emitter of the second switching device is connected to and grounded.

[0018] A circuit board includes the aforementioned power supply circuit including a scanning drive circuit for a high-voltage digital electron tube, and also includes a first PCB board, wherein the scanning drive circuit for the high-voltage digital electron tube is disposed on one side of the first PCB board.

[0019] Furthermore, the first PCB board has a metallized half-hole on its periphery; it also includes a second PCB board and pads, the second PCB board has a metallized half-hole on its periphery; the PCB board and the metallized half-hole of the second PCB board together form a metallized through hole, the pads and the metallized through hole are provided with mounting through holes at corresponding positions, the fasteners pass through the metallized through hole and the mounting through hole in sequence; the fasteners are provided with a conductive layer on their surface.

[0020] An electronic clock, including the aforementioned power supply circuit, includes a scanning drive circuit for a high-voltage digital vacuum tube.

[0021] Compared with the prior art, the technical solution of this utility model and its beneficial effects are as follows:

[0022] (1) The scanning drive circuit of the high-voltage digital vacuum tube of this utility model, when it is necessary to light up a certain number of a certain vacuum tube, the controller controls the opening of the first switch corresponding to the vacuum tube, so that the vacuum tube is connected to the driving power supply and the vacuum tube is selected; the controller controls the opening of the second switch corresponding to the required number, so that the cathode of the corresponding number of the vacuum tube is grounded, thereby realizing the connection of the driving power supply, the first switch, the vacuum tube (selected number), the second switch, and the ground, forming a loop, thereby lighting up the required number of the vacuum tube. Through this row and column scanning drive method, the number of I / O ports of the controller motherboard required is the sum of the ten numbers 0-9 and the number of vacuum tubes, which effectively reduces the number of I / O ports of the controller motherboard required, and there is no need to use high voltage series-to-parallel chips or high voltage transistor array chips, thereby effectively controlling the cost.

[0023] (2) A Zener diode is provided between the emitter and collector of each second switch in this utility model, which can effectively clamp the voltage of the cathode of the glow tube, thereby effectively improving the image retention problem caused by all second switches sharing the same cathode drive.

[0024] (3) The output terminal of the power supply circuit of this utility model is grounded through a high voltage resistant electrolytic capacitor or solid capacitor, which effectively suppresses the noise volume generated under load changes with a scanning frequency of 50Hz and above. Attached Figure Description

[0025] Figure 1 This is a circuit diagram of the controller provided in Embodiment 1 of this utility model;

[0026] Figure 2 This is a schematic diagram of the cathode driving circuit provided in Embodiment 1 of this utility model;

[0027] Figure 3 This is a schematic diagram of the power supply circuit provided in Embodiment 1 of this utility model;

[0028] Figure 4 This is a schematic diagram of the anode drive circuit provided in Embodiment 1 of this utility model;

[0029] Figure 5 This is a circuit diagram of the glow tube carrier provided in Embodiment 1 of this utility model. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0031] Example 1

[0032] A scanning drive circuit for a high-voltage digital vacuum tube includes a controller, an anode drive circuit, and a cathode drive circuit. The anode drive circuit includes several pairs of first switches, the output terminals of which are connected one-to-one with the anodes of the vacuum tube; the control terminals of the first switches are connected to the controller; and the input terminals of the first switches are connected to a drive power supply. The cathode drive circuit includes several second switches, with identical numbers of the vacuum tube anodes connected to one terminal of the same second switch; the control terminals of the second switches are each connected to the controller; and the other terminals of the second switches are all grounded.

[0033] When a specific number on a vacuum tube needs to be illuminated, the controller activates the first switch corresponding to that tube, connecting the tube to the drive power supply and selecting that tube. The controller then activates the second switch corresponding to the desired number, grounding the cathode of that number on the tube. This creates a circuit connecting the drive power supply, the first switch, the selected tube, the second switch, and ground, thus illuminating the desired number on the tube. This row-column scanning drive method requires only the sum of ten digits, the decimal point, and the number of vacuum tubes on the controller motherboard, effectively reducing the number of I / O ports used. It also eliminates the need for high-voltage serial-to-parallel converters or high-voltage transistor arrays, thus effectively controlling costs.

[0034] See Figure 1In this embodiment, the controller's mainboard uses a 48-pin microcontroller, such as the STC8H8K64U-QFN48.

[0035] See Figure 2 In this embodiment, the second switching device uses high-voltage NPN transistors Q0-Q9. The base of the NPN transistor is connected to the controller, the collector of the NPN transistor is connected to the cathode of the electron tube, and the emitter of the NPN transistor is connected to and grounded. When a certain number needs to be lit, the controller sends a high level to the base of the transistor corresponding to that number. Zener diodes ZD2-ZD11 are connected between the collector and emitter of the NPN transistors, and Zener diodes ZD2-ZD11 correspond one-to-one with the second switching devices Q0-Q9. The anode of Zener diodes ZD2-ZD11 is connected to the emitter of the second switching device. Since scanning drive is prone to image retention, placing a Zener diode between the emitter and collector of each second switching device can effectively clamp the voltage of the glow tube cathode, thereby effectively improving the image retention problem caused by all second switching devices sharing a cathode drive.

[0036] See Figure 3 The drive circuit also includes a power supply circuit, which includes a flyback circuit or a boost circuit to increase the lower 3-5V or 9-12V voltage to 140V or higher, with an output current of several mA or tens of mA. The output terminal of the power supply circuit is grounded through capacitor C5. Capacitor C5 is a high-voltage electrolytic capacitor or solid-state capacitor, such as a through-hole aluminum electrolytic capacitor (400V / 2.2μF electrolytic capacitor), and it is a non-multilayer stacked structure. For example, MLCC multilayer ceramic capacitors cannot be used. Therefore, the noise level generated under load changes at a scanning frequency of 50Hz is greatly reduced. Larger-capacity, high-voltage electrolytic capacitors or solid-state capacitors can be selected to further reduce noise, depending on the actual application.

[0037] In this embodiment, the electron tube is a glow discharge tube, and its anode drive power supply voltage is 140V to 250V, meaning the output voltage of the power supply circuit is 140V to 250V. It can be understood that increasing the drive power supply voltage can improve the brightness of the glow discharge tube. A current-limiting resistor (not shown) is also provided between the first switching element and the anode of the glow discharge tube. If this current-limiting resistor is not provided, there is no current-limiting resistor consuming voltage, and the utilization rate of the high-voltage drive power supply is the highest. However, in case of program or circuit failure, a 0-ohm resistor (i.e., no current-limiting resistor) can easily lead to problems such as overload of the high-voltage circuit. Setting a current-limiting resistor can improve the safety of the circuit. The resistance value of the current-limiting resistor can be set according to requirements, for example, hundreds of ohms or thousands of ohms. Preferably, the current-limiting resistor can be set to less than or equal to 1KΩ. The peak brightness of the glow tube under pulse power supply can be increased by increasing the operating voltage and reducing the current limiting resistor to meet the overall brightness of the glow tube when using scanning drive. For example, by using a 190V driving voltage + 1K current limiting resistor (or without the resistor), the brightness of the glow tube can reach about 80% of the static drive brightness when scanning the glow tube. The voltage and the matching resistor can be finely adjusted.

[0038] See Figure 4 In this embodiment, the first switching element is a composite transistor. The number of first switching elements corresponds to the number of glow discharge tubes. Taking the first composite transistor corresponding to the first glow discharge tube as an example, the first composite transistor includes a first transistor HQ1 and a second transistor HQ2. The base of the first transistor HQ1 is connected to the controller, the emitter of the first transistor HQ1 is grounded, and the collector is connected to the base of the second transistor HQ2. The collector of the second transistor HQ2 is connected to the driving power supply VH, and the emitter of the second transistor HQ2 is connected to the anode of the electron tube. A pull-up resistor T1R1 is also connected in series between the collectors of the first transistor HQ1 and the second transistor HQ2. In this embodiment, both the first transistor HQ1 and the second transistor HQ2 are high-voltage NPN transistors. When the input signal CNA1 of the input controller is low, the first transistor HQ1 is cut off, the base of the second transistor HQ2 is pulled high, and the second transistor HQ2 is turned on, thereby turning on the drive power supply VH and the glow discharge tube.

[0039] See Figure 5Taking four glow discharge tubes, each capable of displaying the numbers 0-9, as an example, to illuminate the second glow discharge tube with the number "6", the controller inputs a low-level signal CNA2 to the control terminal of the second glow discharge tube. This cuts off transistor HQ3, turns on transistor HQ4, and activates the anode of the second glow discharge tube, driving the voltage. Simultaneously, the controller inputs high-level signals CNA1, CNA3, and CNA4 to the other three glow discharge tubes, disconnecting them from the driving power supply VH. At the same time, the controller sends a high-level control signal T1CN6 to the second switch Q6, turning on Q6. This creates a power supply loop: driving power supply VH - transistor HQ4 - second glow discharge tube anode - number 6 - second switch Q6 - ground, thus enabling the second glow discharge tube to display the number 6.

[0040] Example 2

[0041] A circuit board includes a first PCB board. The scanning drive circuit of the high-voltage digital electron tube described in Embodiment 1 is arranged on one side of the first PCB board, thereby allowing the first PCB board to be flatly attached to a soldering board or other carrier board. In this embodiment, the periphery of the first PCB board is provided with metallized half-holes to facilitate SMT or manual soldering assembly, thereby reducing soldering difficulty and cost.

[0042] The circuit board also includes a second PCB board and pads. The second PCB board has metallized half-holes around its perimeter. The metallized half-holes of the first and second PCB boards together form a metallized through-hole. Mounting through-holes are provided at the corresponding locations of the pads and the metallized through-holes. Fasteners are passed through the metallized through-holes and mounting through-holes in sequence, thereby pressing the first and second PCB boards onto the pads. The fasteners have a conductive layer on their surface, such as nickel or copper plating on the screw surface. The fasteners not only enable the mounting of the first and second PCB boards but also achieve electrical connection between them, thus saving the need for dedicated board connectors. The half-hole design also effectively reduces the circuit board size and makes disassembly and maintenance more convenient; the PCB board can be removed for maintenance simply by unscrewing the fasteners.

[0043] Example 3

[0044] This embodiment also provides an electronic clock, including the scanning drive circuit of the high-voltage digital vacuum tube described in Embodiment 1. Of course, the scanning drive circuit of the high-voltage digital vacuum tube can also be applied to other products, such as calculators, timers, desktop electronic clocks, electronic calendars, and electrical instrument panels such as voltmeters and frequency meters, which require multiple glow tubes to display multiple numbers.

[0045] The foregoing description illustrates and describes preferred embodiments of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the present invention through the foregoing teachings or related technical or knowledge. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A scanning drive circuit for a high-voltage digital vacuum tube, characterized in that, include: Controller; An anode driving circuit includes a plurality of first switching elements, the output terminals of the first switching elements being connected one-to-one with the anodes of the electron tube, the control terminals of the first switching elements being connected to the controller, and the input terminals of the first switching elements being connected to the driving power supply. A cathode driving circuit includes several second switching devices, with the same number of the electron tubes connected to one terminal of the same second switching device; the control terminals of the second switching devices are respectively connected to the controller, and the other terminals of the several second switching devices are all grounded.

2. The scanning drive circuit for the high-voltage digital electron tube according to claim 1, characterized in that, A Zener diode is connected between one terminal and the other terminal of the second switching element, and the Zener diode corresponds one-to-one with the second switching element; wherein the anode of the Zener diode is connected to the other terminal of the second switching element.

3. The scanning drive circuit for the high-voltage digital electron tube according to claim 2, characterized in that, It also includes a power supply circuit, which includes a flyback circuit or a boost circuit. The output terminal of the power supply circuit is grounded through a capacitor, which is a high-voltage electrolytic capacitor or a solid-state capacitor.

4. The scanning drive circuit for the high-voltage digital electron tube according to claim 3, characterized in that, The power supply circuit outputs a drive voltage of 140V to 250V.

5. The scanning drive circuit for the high-voltage digital electron tube according to claim 4, characterized in that, A current-limiting resistor is also provided between the first switching element and the anode of the electron tube.

6. The scanning drive circuit for the high-voltage digital electron tube according to claim 1, characterized in that, The first switching device is a composite transistor, including a first transistor and a second transistor. The base of the first transistor is connected to the controller. The emitter of the first transistor is grounded, and the collector is connected to the base of the second transistor. The collector of the second transistor is connected to the power supply, and the emitter of the second transistor is connected to the anode of the electron tube. A pull-up resistor is also connected in series between the collectors of the first transistor and the second transistor.

7. The scanning drive circuit for the high-voltage digital electron tube according to claim 1, characterized in that, The second switching device is an NPN transistor. The base of the second switching device is connected to the controller, the collector of the second switching device is connected to the cathode of the electron tube, and the emitter of the second switching device is grounded.

8. A circuit board, characterized in that, The device includes a scanning drive circuit for a high-voltage digital vacuum tube as described in any one of claims 1 to 7, and further includes a first PCB board, wherein the scanning drive circuit for the high-voltage digital vacuum tube is disposed on one side of the first PCB board.

9. The circuit board according to claim 8, characterized in that, The first PCB board has metallized half-holes around its perimeter; It also includes a second PCB board and pads. The periphery of the second PCB board is provided with metallized half-holes. The metallized half-holes of the first PCB board and the second PCB board together form a metallized through hole. The pads are provided with mounting through holes at the corresponding positions of the metallized through hole. Fasteners pass through the metallized through hole and the mounting through hole in sequence. The surface of the fastener is provided with a conductive layer.

10. An electronic clock, characterized in that, The scanning drive circuit includes the high-voltage digital electron tube as described in any one of claims 1 to 7.

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