JPH03180916A - Electronic apparatus with display tube display - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention comprises a display section using a fluorescent display tube that displays two numbers, etc. by using fluorescent light emitted by thermionic energy. This invention relates to electronic devices with display tubes, such as electronic desktop calculators.

<Prior art> Electronic devices that require a display, such as electronic desktop calculators, generally have a display using a liquid crystal display element because of its low power consumption, but this liquid crystal display element is very difficult to read. Because of these drawbacks, fluorescent display tubes are generally used in business-use electronic desktop calculators where ease of viewing is important.

A conventional electronic desktop calculator equipped with such a fluorescent display tube has a configuration as shown in FIG.

That is, when the power switch SW is turned on, AC power from the power transformer T is full-wave rectified by the diode bridge DB, smoothed by the capacitor C1, and converted to DC power, and then supplied to the filament voltage generation circuit FV. Ru.

In the filament voltage generation circuit FV, the input DC current is supplied to the base through the resistor R1, turning on the transistor Q1, the voltage is made constant by the Zener diode Z1, and the voltage is supplied to the base through the capacitor C2 and the resistor R2.
．． A filament I voltage of 5V is created and supplied to the fluorescent display tube Dis. In addition, 3.5 is applied to both ends of resistor R2.
A cutoff voltage V cut of V is generated.

On the other hand, the AC power from the power transformer T is converted into DC by the diode D and capacitor C3 and then supplied to the constant voltage circuit RC, and this DC current is supplied to the base via the resistor R3. Q2 is turned on, the voltage is made constant by the Zener diode Z2, and the voltage is further turned on by the capacitor 5: +J C4, the Zener diode Z3. Potential V is applied to the three output terminals via resistor R4 and content C5. C (+5V), potential GND (OV) and potential V
NG (25V) appears, and the central processing unit CP
It is supplied to U as its driving voltage and display voltage.

Note that the DC power converted by the diode bridge DB and the capacitor C3 is also supplied to the printer power supply circuit P.

<Problems to be Solved by the Invention> By the way, when the power switch SW is turned off, the line with the common potential VNG of the entire system is disconnected, so the power to all circuit sections including the RAM is cut off. , the data previously stored in the RAM is erased by key input.

By the way, electronic desk calculators equipped with fluorescent display tubes (DIS) are mainly used for business purposes, as mentioned above, and key input operations are often interrupted for relatively long periods of time, for example in tax calculation work. It will be done. In such a case, the actual situation is that the display section is forced to remain in the display state in order to retain the data content, and power is wasted.

The present invention was made in response to these conventional problems, and provides a display tube that can reduce power consumption as much as possible by turning off the power switch when not in use, and can retain previously input data. The technical problem is to provide a molded device.

<Means for Solving the Problems> The present invention constitutes a display tube display type electronic device as described below, as a technical means for solving the problems mentioned above. That is, in a display tube display type electronic device that uses a fluorescent display tube as a display section, which displays by supplying filament voltage from a filament voltage generation circuit and inputting a display signal from a central processing unit, the power supply section and the filament voltage generation circuit, a constant voltage circuit that generates a driving voltage and a display voltage to be supplied to the central processing unit can be connected to the power supply unit without going through the power switch. A detection circuit for detecting the on/off state of the power switch is provided, and when an off detection signal is input from the detection circuit to the central processing unit, the central processing unit does not accept key input and does not output a display signal. The present invention is characterized in that an off mode setting means for setting an off mode is provided.

Function> When the power switch is turned on, power is supplied to the ficimen 1 to the voltage generating circuit to supply filament voltage to the fluorescent display tube. On the other hand, the constant voltage circuit is always connected to the power supply section without going through a power switch, and supplies the central processing unit with the drive voltage and display voltage.
The detection circuit detects the on state of the power switch and does not output an off detection signal to the central processing unit, so the central processing unit outputs a display signal to the fluorescent display tube based on key input etc. The input data is displayed on the display tube.

When the power switch is turned off, the filament voltage generation circuit is disconnected from the power supply section, and no filament voltage is supplied to the fluorescent display tube. Also, an off detection signal is input from the detection circuit to the central processing unit, and the Since the processing device sets the off mode and does not accept key inputs and does not output display signals, power consumption becomes extremely low. Moreover, since the central processing unit is constantly supplied with driving voltage from the constant voltage circuit, the data content that has been input up to that point is retained without being lost.

<Example> Hereinafter, a preferred example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a circuit configuration of an embodiment of the present invention, and in this figure, the same or equivalent parts as in FIG. 4 are given the same reference numerals, and the explanation thereof will be omitted. The difference from FIG. 4 is that the power switch SW is inserted and connected between the diode bridge DB and the input terminal of the filament voltage generation circuit FV, and the on/off detection circuit DC of the power switch SW
It has only a configuration in which a processing program as shown in FIG. 2 is added to the central processing unit CPU.

Next, the operation of the above embodiment will be explained. When the power switch SW is turned on, the filament voltage generation circuit FV is connected to the power supply section, the transistor Q1 is turned on and driven, and the filament voltage Vr and cutoff voltage V cut are output. On the other hand, the constant voltage circuit RC is in a driving state as long as the AC cord is connected to the commercial power supply regardless of whether the power switch SW is on or off, and has a potential VCC (+5 V), a potential GND (OV), Potential V
NG (25V) is supplied to the central processing unit CPU as its drive voltage and display voltage.

At this time, the voltage between points A and B, that is, 4
．． A voltage of 8V, which is the sum of the filament voltage V of 5V and the cutoff voltage of 3.5V, is applied through resistors R5 and R6, which turns on transistor Q3 and causes a collector current to flow through resistor R7. When the current flows, the transistor Q4 turns on, and this transistor Q4
A voltage at the level of the potential VCC is input to the detection input port D1 of the central processing unit CPU through the detection input port D1 of the central processing unit CPU.

The signal processing of the central processing unit CPU at this time will be explained with reference to FIG. First, the input signal level of the detection input port D1 is determined (step Sl), and as described above, V,
When the c level is input, the operation mode is set (step S2), and the contents of the X register for storing and displaying the calculation results are cleared (step S3).
). Then, the contents of the cleared X register, that is, “
0. ” while waiting for key input (step S5). That is, when there is no key input, the input signal level of the detection input port D1 is V. . Determine whether the level is (
Step S7), a loop of Step S4, Step S5, and Step S7 is cycled.

When a key signal is input, a calculation is performed on the input key signal, and the calculation result is printed and stored in the X register (step S6).
After that, jump to step S4 and display the fluorescent display tube DIS.
Thereafter, the loop from step 84 to step S6 is repeated every time a key is input.

Next, when interrupting the key input operation, switch the power switch S.
When W is turned off, the filament voltage generation circuit FV is disconnected, so the voltage between points A and B becomes the VNG level, transistor Q3 and transistor Q4 of the detection circuit DC are turned off, and the voltage at the GND level is turned off. This GND level voltage is input to the detection input port D1 of the central processing unit CPU via the resistor R8.
It is determined in either step S1 or step S7 in the figure, and first, the display is disappeared (step S8), the off mode is set, no key input is accepted in step 39), and the output port for driving the display tube ( (not shown) to VNG level.

At this time, the filament voltage generating circuit FV is in a non-driving state and no filament voltage is supplied to the fluorescent display tube DIS, so power consumption is extremely small.・It is always connected to the power transformer T and is in a driving state regardless of whether it is off, and the driving voltages are applied to the central processing unit CPU by applying the potential Vcc (1-5V), the potential GND (OV), and the potential VNG (25V) to the central processing unit CPU. Since it is supplied as a display voltage, the input contents up to that point are retained.

FIG. 3 shows the overall block configuration, and shows the central processing unit C.
The PU is driven by being supplied with a driving voltage and a display voltage from a constant voltage circuit RC, and is driven by a fluorescent display tube based on signal inputs from a key matrix K, a power-on ACL means POA, and the aforementioned detection circuit DC. The entire device such as the printer PT is controlled via the DIS and the printer driver PD.

<Effects of the Invention> As described above, according to the display tube display type electronic device of the present invention,
When the power switch is turned off, the filament I voltage supply is automatically stopped and one off mode is set, so power consumption is extremely low (and the central processing unit is always powered on). The input contents can be retained without being lost.In particular, the present invention can be applied to business-use electronic desktop calculators to obtain extremely remarkable effects.

[Brief explanation of drawings]

Figure 1 is an electrical circuit diagram of one embodiment of the present invention, and Figure 2 is the electrical circuit diagram of one embodiment of the present invention.
3 is a block diagram showing the overall configuration, and FIG. 4 is an electrical circuit diagram of a conventional electronic device. FV-filament voltage generation circuit P U IS 'F W DC DC Central processing unit Fluorescent display tube power transformer (power supply section) Power switch constant voltage circuit detection circuit

Claims (1)

[Claims] (1) In a display tube display type electronic device that uses a fluorescent display tube as a display section, which displays by supplying filament voltage from a filament voltage generation circuit and inputting a display signal from a central processing unit, A power switch is inserted and connected between the part and the filament voltage generation circuit,
A constant voltage circuit that generates a driving voltage and a display voltage to be supplied to the central processing unit is directly connected to the power supply unit without going through the power switch, and a circuit for detecting the on/off state of the power switch is provided. , a display characterized in that the central processing unit is provided with an off mode setting means for setting an off mode in which no key input is accepted and no display signal is outputted by inputting an off detection signal from the detection circuit. Tube display type electronic equipment.