JPH0329699Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Application of the Invention) The present invention relates to an improvement of an operation display device for a stationary meter such as an electronic watt-hour meter or an electronic gas meter.

(Background of the invention) As shown in FIG. 4, a conventional general electronic watt-hour meter detects a voltage V proportional to the load voltage and a load current using a power detection circuit 1 consisting of a time-sharing multiplier or the like. A current signal (or voltage signal) corresponding to the power is obtained by multiplying by a current I proportional to the current I, and this current signal is converted into a frequency by a frequency conversion circuit 2,
This frequency is reduced by a certain percentage by a frequency dividing circuit 3, and the divided output is integrated by a counter 4 and displayed as an amount of electric power. The electronic electricity meter is
Since it is a stationary meter that does not have a rotating part like the disc of an inductive watt-hour meter, it is difficult to check the operating status, especially at light loads. An operation display device 5 built into the electronic watt-hour meter was driven by relatively high-frequency pulses output from an appropriate frequency dividing stage. An example of a conventional operation display device 5 is shown in FIG. By applying the pulse from the frequency dividing circuit 3 to the base of the transistor Tr via the resistor _R1 ,
The transistor Tr is intermittently turned on and the power supply voltage +V ₁ is applied to the light emitting diode LED through the resistor R ₂ . As a result, the light emitting diode LED,
It flashes light at a flashing cycle depending on the power consumption of the load.

However, since watt-hour meters are often installed outdoors, the operation display device 5 has attracted much more attention than inductive watt-hour meters because it flashes and emits light even at night. As a result, third parties are made aware of and informed of the consumer's electricity usage, which is undesirable in terms of protecting the consumer's privacy and crime prevention. Furthermore, flashing lights at night give viewers a strange feeling, such as ``creepy'' or ``the meter is on fire.''

(Purpose of the invention) An object of the invention is to solve the above-mentioned problems and provide an operation display device for a stationary instrument that makes light emission less noticeable at night.

(Characteristics of the invention) In order to achieve the above object, the present invention provides a control means to reduce the light emission intensity of the light emitting element according to the darkness of the surroundings. It is characterized by making the intensity not much different from the surrounding darkness.

(Embodiment of the invention) FIG. 1 shows an embodiment of the invention using a photoconductive element as a control means. Components similar to those in FIG. 5 are given the same reference numerals.

A resistor R ₃ and a photoconductive element R ₄ are connected in series to the light emitting diode LED. The photoconductive element _R4 is a cadmium sulfide cell or the like, and is placed at a position where it can detect the surrounding brightness. When the voltage applied to the photoconductive element _R4 is constant, the magnitude of the current flowing through the photoconductive element _R4 changes in proportion to the amount of light in the surroundings, so when the surroundings are bright, a large current flows through the light emitting diode LED. The flashing light of the light emitting diode LED becomes brighter, and the operation display is clearly performed. When the surroundings become dark, only a small current flows through the light-emitting diode LED, and the flashing light from the light-emitting diode LED becomes dim, to the extent that it is barely visible or invisible. Therefore, the blinking light emission of the light emitting element LED at night can be made inconspicuous.
When checking the operation display at night, by shining a flashlight on the photoconductive element _R4 , the light emitted from the light emitting diode LED will become brighter, allowing you to clearly see the operation display.

FIG. 2 shows another embodiment of the invention using a photovoltaic element as the control means.

In this embodiment, a photocoupler PCP is used instead of the transistor Tr, and by inputting the pulse from the frequency divider circuit 3 through the resistor _R5 ,
Photocoupler PCP turns on intermittently.

A photodiode, a phototransistor, a selenium photovoltaic cell, a silicon solar cell, etc. are used as the photovoltaic element PC ₁ . The voltage generated by the photovoltaic element _PC1 is amplified by an amplifier consisting of an operational amplifier A and a resistor _R6 , and its output voltage _V2 is applied to the light emitting diode LED via a resistor _R7 . The photovoltaic element PC ₁ , like the photoconductive element R ₄ , is placed at a position where it can detect the surrounding brightness. The photovoltaic element PC ₁ generates a voltage proportional to the incident light, so when the surroundings are bright, the output voltage V ₂ of the operational amplifier A increases, and a large current flows through the light emitting diode LED. The flashing light becomes brighter and the operation is clearly displayed. When the surroundings become dark, the output voltage _V2 of the operational amplifier A becomes small, and only a small current flows through the light emitting diode LED, and the blinking light emission of the light emitting diode LED becomes dim and becomes barely visible or invisible.

FIG. 3 shows another embodiment of the present invention using a photovoltaic element, a comparator, an electronic switch, etc. as the control means.

A comparator CP is connected to a bridge circuit consisting of a photovoltaic element PC ₂ and resistors R ₈ to _{R 10} , and the output of the comparator CP drives electronic switches S ₁ , S via a resistor R ₁₁ , a driver DR ₁ , and an inverting driver DR ₂ . ₂ can be turned on and off. Resistors R ₁₂ and R ₁₃ are connected in series to the electronic switches S ₁ and S ₂ , respectively, and R ₁₂
<R ₁₃ . ZD is a zener diode.

When the surroundings are bright, the current flowing through the photovoltaic element PC ₂ increases, the potential at the inverting input terminal of the comparator CP becomes higher than that at the non-inverting input terminal, and the output of the comparator CP becomes a low level. As a result, electronic switch _S2 is turned on and electronic switch _S1 is turned off, a large current flows through the light emitting diode LED through resistor _R12 , and the flashing light of the light emitting diode LED becomes brighter, making the operation display clear. be exposed. When the surroundings become dark, the output of comparator CP is inverted to high level, and electronic switch _S1 is turned on.
Electronic switch ₂ is turned off and the light emitting diode
A small current flows through the LED through the resistor _R13 , and the flashing light of the light emitting diode LED becomes dim.

In this embodiment, the light emission intensity of the light emitting diode LED is controlled in stages, but the control is not limited to two stages, but can also be in three or more stages. In that case, the light emitting diode LED may be configured not to emit any light when the surroundings become the darkest.

(Modification) In the illustrated embodiment, the light emitting element is a light emitting diode.
Although LEDs are shown, neon tubes, incandescent lamps, etc. may also be used. Further, instead of blinking light emission, it may be one that emits light continuously, or it may be one that consists of a plurality of lights that emit light in a cyclical manner.

(Effects of the Invention) As explained above, according to the present invention, a control means is provided to reduce the light emission intensity of the light emitting element according to the surrounding darkness, so that when the surrounding becomes dark, the light emitting element emits less light. Since the intensity of the light is not much different from the surrounding darkness, it is possible to make the light emitted at night less noticeable.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing one embodiment of the present invention;
Fig. 3 is a circuit diagram showing another embodiment of the invention, Fig. 4 is a block diagram showing a conventional electronic watt-hour meter, and Fig. 5 is a circuit diagram showing another embodiment of the invention. FIG. 1 is a circuit diagram showing a conventional operation display device. 1... Power detection circuit, 2... Frequency conversion circuit,
3...Frequency dividing circuit, 4...Counter, 5...Operation display device, LED...Light emitting diode, Tr...Transistor, _R4 ...Photoconductive element, _PC1 , _PC2 ...Photovoltaic element, PCP...Photocoupler, CP...Comparator, _S1 , _S2 ...Electronic switch, _R12 ,
R ₁₃ ...Resistance.

Claims (1)

[Scope of utility model registration request] An operation display device for a stationary instrument including a light emitting element that indicates the operation of the stationary instrument by emitting light, characterized by comprising a control means for lowering the light emission intensity of the light emitting element according to surrounding darkness. An operation display device for stationary instruments.