JPH02230696A - Power source device for vacuum tube type light emitting tube - Google Patents

Abstract

PURPOSE:To make it possible to regulate the luminance from low to high levels by making the voltage applied to a control electrode a square-shaped wave and varying the amount of emitted light by changing the pulse width of the square wave. CONSTITUTION:A square wave voltage is applied from a square wave generating circuit 4 to a grid G of a tetrode vacuum tube type light emitting tube 1 and a DC high voltage is applied from a DC-DC converter 2 to a plate P of the tetrode vacuum tube type light emitting tube. A square wave time ratio control voltage is applied from a terminal 5 to a circuit 4. The time ratio of light emitting duration to non-emitting duration is changed by changing the time ratio of the square wave at a frequency higher than that which can be perceived by human eye. As a result, the human eye perceives the brightness of the average value. Thus, the luminance is regulated. By synchronizing the square wave voltage applied to the control electrode with the frequency of the ripple voltage of the voltage applied to the plate, the light emitting surface can be made to emit light uniformly without flicker due to the influence of the ripple voltage of the plate voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power supply device for a vacuum tube type arc tube that can vary the amount of light emitted by applying a voltage to a control electrode, which can be applied to, for example, a backlight source of a display.

[Prior art] Conventionally, this method has been used to adjust the brightness of vacuum tube type arc tubes.
How to adjust plate voltage or how to adjust grid voltage. Furthermore, the cathode. There are methods such as adjusting the beam current generated from the heater. for example. In the method of adjusting grid voltage, a DC voltage is applied to the grid and the brightness is adjusted by the DC voltage value. If you gradually increase the brightness of the vacuum tube type arc tube from the unlit state. Flickering and unevenness occur on the light emitting surface, so unless the brightness is increased to a certain level, the light will not emit light evenly. Therefore. When used at low brightness, the light is not emitted uniformly. There was a practical problem.

[Problem to be solved by the invention] In vacuum tube type arc tubes, the plate current is controlled by grid voltage, as in normal vacuum tubes and cathode ray tubes. Alternatively, it is possible by changing the beam current generated from the cathode or heater. For example, if the light emitting part is flat. To make that plane emit light uniformly and without flickering. Physical precision of vacuum tube electrodes and light emitters. This is extremely difficult due to the distortion of the electrodes due to temperature.

The present invention was made in view of the above circumstances, and allows adjustment from low brightness to high brightness. Another object of the present invention is to provide a power supply device for a vacuum tube type arc tube that can uniformly emit light from low to high brightness without flickering.

[Means and effects for solving the problem] The present invention is intended to achieve the above object. In a vacuum tube arc tube power supply device that can vary the amount of light emitted by changing the voltage applied to the control electrode. The voltage applied to the control electrode is a square wave. A device characterized by changing the pulse width of this square wave to vary the amount of light emitted from the vacuum tube type arc tube, or by synchronizing the square wave voltage applied to the control electrode with the frequency of the ripple voltage of the voltage applied to the plate. It is characterized by the following. The control electrode voltage is adjusted by the duty ratio of the square wave voltage to adjust the brightness (light-emitting portions and non-light-emitting portions are controlled by pulse width).

[Example] Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the invention. In other words. The tetrode vacuum tube type arc tube 1 includes a plate P, a grid G, a heater H, and a back plate BP for scattering the electron beam.
It's more. The amount of light emitted can be varied by changing the voltage applied to the grid G. As shown in FIG. 2, this tetrode vacuum tube type arc tube 1 has a plate P formed into a flat body consisting of an electrode and a light emitting surface, and a DC high voltage is applied to this plate P from a DC-DC converter 2. Heater power supply 3 is connected to heater H. The electron beam emitted from the heater If is boom! By being hit by No-}-P. Plate P
The light-emitting surface emits light. The amount of light emitted is approximately 20,000 candela or more. Emission brightness is controlled by controlling the voltage applied to grid G. This is also possible by controlling the electron beam from the heater H.

That is. DC-D is installed on the plate P of the tetrode vacuum tube type arc tube 1.
DC high voltage is applied from C converter 2, and grid G
A square wave voltage (pulse) is applied from the square wave generating circuit 4 to . A square wave ratio control voltage is applied to the square wave generating circuit 4 from a terminal 5. By changing the time ratio of the square wave voltage, the time ratio between the light emitting time and non-emitting time of the plate P is changed at a frequency higher than that which can be detected by the human eye, so that the human eye perceives the average brightness. You can adjust the brightness from

3 and 4 show other embodiments of the invention.

3 shows a synchronous circuit 6 provided between the DC-DC converter 2 of FIG. 1 and the square wave generation circuit 4, and FIG. 4 shows a second embodiment of the DC-DC converter 2 of FIG. 3. and the grid control circuit 7 in detail.

That is. The DC-DC converter 2 is . DC input terminal 8
,9. Capacitor C1, switching transistor T
RI. }Lance Tl, rectifier diode D1 and capacitor C2, DC output terminal 10.11. It is composed of a control circuit 12 for controlling the transistor TRI and an oscillation circuit 13. The grid control circuit 7 is composed of a square wave generation circuit 4, a synchronization circuit 6, and a square wave duty ratio control circuit 14.

Next, let me explain the operation. The DC voltage E1n applied to the DC input terminals 8 and 9 is applied to the switching transistor TRI.
Due to the switching operation of An alternating current voltage is generated on the secondary side of the transformer T1. This AC voltage is rectified and smoothed by a rectification and smoothing circuit consisting of a diode D1 and a capacitor C2, and a high DC voltage is output to the output terminals 10 and 11. It is added to the plate P of the tetrode vacuum tube type arc tube 1. in this case. The switching transistor TRI is switched by a control circuit 12 having an oscillation circuit 13.

Also. In the square wave generation circuit 4. Square wave duty ratio control circuit] The duty ratio of the square wave voltage is changed by the square wave duty ratio control voltage from 4. In this case, a signal for controlling the duty ratio using a DC voltage is applied to the square wave duty ratio control circuit 14 from the terminal 20. At the same time as this. In the synchronous circuit 6. A synchronizing signal from the oscillation circuit 13 of the DC-DC converter 2 is detected. Using this synchronization signal. In the square wave generation circuit 4. A square wave voltage with a variable duty ratio is generated in synchronization with the switching frequency of the DC-DC converter 2. Add to grid G of tetrode vacuum tube type arc tube 1. still. What is the specific synchronization method? There are various methods.

FIG. 5 shows the plate and grid voltages for the embodiment of FIGS. 3 and 4. FIG. That is. The ripple voltage waveform 150 frequency of the plate voltage and the square wave of the grid voltage are synchronized. The pulse width of the square wave of the grid voltage is indicated by the arrow 16.
Alternatively, the relative brightness can be controlled by changing as shown in 17. 18 is a high brightness emission level. 19
is the level at which no light is emitted.

next. The effects of this embodiment will be explained. That is. Since the luminance of the emitted light changes depending on the voltage applied to the plate of the tetrode vacuum tube type arc tube, the luminance of the emitted light is modulated by the ripple voltage included in the voltage applied to the plate. in this case.
Even if the frequency of the ripple voltage is a frequency that humans cannot detect. A beat is generated by the frequency of the ripple voltage and the frequency of the square wave voltage applied to the grid. Flickering (uneven brightness) occurs on the light emitting surface. Therefore, in this embodiment, by synchronizing the frequency of the square wave voltage applied to the grid and the switching frequency of the DC-DC converter that generates the high DC voltage applied to the plate, the ripple voltage generated by the ripple voltage of the plate voltage and the grid voltage is generated. There is no beat, and the flickering of the light emitting surface is eliminated, allowing uniform light emission and stable adjustment from low to high brightness light emission.

6. In the above embodiment, the case where a grid is used as a brightness control electrode has been described, but the present invention is not limited to this. The same effect can be achieved by using a cathode as a brightness control electrode or by controlling an electron beam from a heater.

5 In the above embodiment, DC is used to generate the plate voltage etc.
- Although the case where a DC converter is used has been explained, it is not limited to this, and regardless of the method or type. Any power source that has an oscillation circuit inside the power source can be applied.

[Effects of the Invention] As described above, the present invention provides a power supply device for a vacuum tube type arc tube in which the amount of light emitted can be varied by the voltage applied to the control electrode. By making the voltage applied to the control electrode a square wave, and changing the pulse width of this square wave to vary the amount of light emitted from the vacuum tube type arc tube. It can be easily adjusted from low brightness to high brightness. In addition, by synchronizing the square wave voltage applied to the control electrode with the frequency of the ripple voltage of the voltage applied to the plate, the light emitting surface can emit light uniformly without flickering from low to high brightness without being affected by the ripple voltage of the plate voltage. can be done. Furthermore. Flicker can be prevented even when the ripple voltage of the plate voltage is made relatively large. High-voltage decoupling capacitors for plate voltage can be used with less than half the capacity of conventional capacitors. It is safe because the number of special parts for high voltage can be reduced. Moreover, a small and inexpensive power supply device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing one embodiment of the present invention, and FIG. 2 is a perspective view showing an example of a tetrode vacuum tube type arc tube according to the present invention.
FIG. 3 is a configuration explanatory diagram showing another embodiment of the present invention, and FIG. 4 is a circuit diagram showing an example of the DC-DC converter and grid control circuit according to the present invention. FIG. 5 is a waveform diagram showing an example of plate voltage and grid voltage according to the present invention. 1... Tetrode vacuum tube type luminous tube. 2...DC-DC converter. 4...Square wave generation circuit. 6...Synchronization signal generation circuit. 12...Control circuit. 13...Oscillation circuit. 14...Square wave time ratio control circuit. Applicant's Representative Patent Attorney Takehiko Suzue

Claims (2)

[Claims] (1) In a vacuum tube arc tube power supply device in which the amount of light emitted can be varied by a signal applied to the control electrode or cathode electrode, the voltage applied to the control electrode is a square wave, or the voltage applied to the control electrode is a square wave, or the electrons generated from the cathode electrode or heater are A power supply device for a vacuum tube type arc tube, characterized in that a beam controlling signal is a square wave, and the amount of light emitted from the vacuum tube type arc tube is varied by changing the pulse width of the square wave. (2) A claim characterized in that the square wave voltage applied to the control electrode or the square wave signal that controls the electron beam generated from the cathode electrode or the heater is synchronized with the frequency of the ripple voltage of the voltage applied to the plate. Item 1. A power supply device for a vacuum tube type arc tube according to item 1.