JPH0329700Y2 - - 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. 2, 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 and 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 the amount of electric power. The electronic electricity meter is
Since it is a stationary meter that does not have rotating parts 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 that corresponds to 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 or 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 switching means for switching the light emission intensity of the light emitting element according to the time of the day, thereby reducing the light emission intensity of the light emitting element at night. The feature is that the darkness does not differ much from the surrounding darkness.

(Embodiment of the invention) FIG. 1 shows an embodiment of the invention. Components similar to those in FIG. 3 are given the same reference numerals.

There is a resistor on the anode side of the light emitting diode LED.
A series circuit of R ₃ and electronic switch S ₁ and a series circuit of resistor R ₄ and electronic switch S ₂ are connected. Resistance R ₂
is determined to be less than the resistance R ₃ . The clock circuit TM outputs a high level signal during daytime hours and a low level signal during nighttime hours. These signals cause driver DR ₁ and inverting driver
Electronic switches S ₁ and S ₂ are turned on and off via DR ₂ . Driver DR ₁ , inverting driver DR ₂
and drivers S ₁ and S ₂ constitute an example of the switching means of the present invention.

During daytime hours, the high-level signal output from the clock circuit TM turns electronic switch _S1 on and electronic switch _S2 off, causing a large current to flow through the light-emitting diode LED via resistor _R3 . The flashing light of the light emitting diode LED becomes brighter, and the operation display is clearly performed.

At night time, the output of the clock circuit TM is reversed to low level, electronic switch _S1 is turned off, electronic switch _S2 is turned on, and the light emitting diode LED is turned off.
A small current flows through the resistor _R4 , and the flashing light from the light emitting diode LED becomes dim and can only be seen faintly. Therefore, the light emitting element LED
It is possible to make the flashing light at night less noticeable.

(Modification) In the illustrated embodiment, the light emitting intensity of the light emitting diode LED is switched in two stages, but the number of time periods is not limited to three or more, for example, daytime, nighttime, and late night.

Although a light emitting diode (LED) is shown as a light emitting element, a neon tube, an incandescent lamp, 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. Further, the clock circuit TM does not need to be provided in the operation display device 5, and may receive only a signal from a clock circuit inside or outside the electronic watt-hour meter.

(Effects of the invention) As explained above, according to the invention, a switching means is provided for switching the light emission intensity of the light emitting element according to the time of the day, so that the light emission intensity of the light emitting element is lowered at night. Since the light does not differ much from the surrounding darkness, the light emitted at night can be made inconspicuous.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention;
The figure is a block diagram showing a conventional electronic watt-hour meter, and FIG. 3 is a circuit diagram showing a conventional operation display device. 1... Power detection circuit, 2... Frequency conversion circuit,
3... Frequency division circuit, 4... Counter, 5... Operation display device, LED... Light emitting diode, Tr... Transistor, TM... Clock circuit, DR ₁ ... Driver, DR ₂ ... Inverting driver, S ₁ , _S2 ...Electronic switch, _R3 , _R4 ...Resistor.

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 means of light emission, characterized in that a switching means is provided for switching the light emission intensity of the light emitting element according to the time of the day. An operation display device for stationary instruments.