JPS633271A - Electronic register - Google Patents

Abstract

PURPOSE:To eliminate the wastage of back-up power consumption by connecting the back-up power source to a display circuit by means of a control element for a display switch when illumination intensity is capable of reading the displayed continuous data of the display circuit and constituting the display operation. CONSTITUTION:When a power supply from an AC/DC conversion source 4 to a power- frequency conversion circuit 1, counter 2 and display circuit 10 is stopped because of service interruption, a power stoppage signal is supplied from the power source 4 to a back-up power source 5 just before the perfect stoppage of the power supply. Then the power is supplied from the power source 5 to a counter 2 and a circuit 10. If the illumination intensity at a liquid crystal display device 12 is bright enough to read the displayed continuous data, an optical switch 13 conducts to supply the power of the power source 5 to a driving circuit 11. Therefore the counted value of the counter 2 is read by the circuit 11 and converted to information of eight segments for each figure to be transmitted to the display device 12, the electric energy up to the power stoppage time is thereon displayed 12. On the other hand, when the illumination intensity at the display device 12 is dim, the optical switch 13 is not conducted and the power of the power source 5 is not supplied to the circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Field of Industrial Application) The present invention relates to an electronic measuring instrument with improved display operation during a power outage.

(Prior Art) FIG. 2 shows a diagram of a conventional electronic power meter as an electronic meter. This power meter measures the circuit under test (
A power-frequency conversion circuit 1 receives a voltage (2) and a consumption current i (not shown), calculates power in a power-frequency conversion circuit 1, converts it into a frequency signal corresponding to this power, and sends it to a counter 2. This counter 2 divides the input frequency signal by a predetermined frequency division ratio and counts the frequency. Then, this count value is sent to the display circuit 3 and displayed as "power".

By the way, these power-frequency conversion circuit 1 and counter 2
The display circuit 3 is operated by being supplied with power from an AC/DC conversion power supply 4 that converts the voltage V of the circuit under test into a DC voltage. In addition, a backup power source 5 is provided to operate the count value of the counter 2 and the display circuit 3 to maintain the count value so that the measured ffi value does not disappear when the power is turned off, and to enable continuous measurement from the time of recovery. There is. As a result, when a power outage occurs, a power outage signal is sent from the AC/DC converter 1.1!4 to the backup power supply 5, and power is supplied from the backup power supply 11325 to the counter 2 and display circuit 3.
is supplied to

Therefore, in the event of a power outage, power is always supplied to the counter 2 and the display circuit 3 to perform display operations. However, the measurement value is read only when the illuminance on the display surface of the display circuit 3 is such that the displayed measurement value can be read, and is not read at night, for example. Therefore, operating the display circuit 3 all the time increases the cost of the backup power source 5 and wastes batteries and the like. This increases the frequency of battery replacement, and furthermore, there is a problem that the number of used batteries increases when many electronic watt-hour meters are used.

Therefore, in order to eliminate such wasteful consumption of the backup unit 5, a manually operated switch 6 is connected between the backup power supply 5 and the display circuit 3 as shown in FIG. There is one that operates to activate the display circuit 3. However, with this measuring instrument, it is troublesome to operate the switch 6 when reading.
Further, for example, the contacts of the switch 6 are worn out due to repeated use, resulting in deterioration of the contact shape and deterioration of reliability. The above-mentioned problems are not limited to electronic wattmeters, but also apply to electronic reactive wattmeters, power factor meters, and the like.

(Problems to be Solved by the Invention) As described above, conventional measuring instruments have problems such as wasteful consumption of backup power and reduced reliability.

SUMMARY OF THE INVENTION Therefore, in order to solve the above-mentioned problems, it is an object of the present invention to provide an electronic measuring instrument that can perform a display operation only when a predetermined illuminance is readable, thereby eliminating wasteful backup power consumption.

[Configuration of the Invention (Means for Solving Problems) The present invention supplies power from a backup power supply to a measurement value holding circuit and a display circuit in the event of a power outage, and at this time, a Display switch II+ 11
(This is an electronic measuring instrument that attempts to achieve the above object by having a configuration in which a backup power source is connected to the display circuit when one element detects that the illuminance is such that the displayed measurement value of the display circuit can be read.

(Function) By providing such a means, when the illuminance reaches such a level that the displayed measurement value of the display circuit can be read, the display switch III
A backup power source and a display circuit are connected by 50 elements to perform a display operation.

(Example) Hereinafter, an example of the present invention will be described with reference to a configuration diagram of an electronic watt-hour meter shown in FIG.

Note that the same parts as in FIG. 2 are given the same reference numerals. Now, the display circuit 10 has a drive circuit 11 constituted by a c-Mos circuit, and a liquid crystal display 12. When the counter 2 receives a count (directly), the drive circuit 11 displays the liquid crystal display 1.
For example, the configuration is such that eight segments of information are sent out for each digit to display the amount of power. Furthermore, the display 12
An optical switch 13 as a display switch ill'l element is provided near the display surface. Specifically, the optical switch 13 is composed of a phototransistor and is turned on when it is detected that a predetermined illuminance, for example, the illuminance at the j value of the display meter 12, can be read. The optical switch 13 is connected between the backup N source 5 and the drive circuit 11, and connects the backup power source 5 and the drive circuit 11 when a predetermined illuminance is detected. Note that the counter 2 is constituted by low current consumption elements such as a C-MO8 circuit and a C-MOS memory, and the backup power source 5 uses a lithium battery or the like.

Next, the operation of the electricity meter configured as described above during a power outage will be explained. When a power outage occurs, the power-frequency conversion circuit 1, counter 2, and display circuit 1 are transferred from the AC/DC conversion power source 4.
When the power supply to o is stopped, a power outage signal is sent from the AC/DC converter m4 to the backup power supply 5 immediately before the power supply is completely stopped. As a result, power is supplied from the backup power supply 5 to the counter 2 and the display circuit 10. Here, if the illuminance on the liquid crystal display 12 is such that the display meter can read the value, the optical switch 13 becomes conductive and supplies the power from the backup N source 5 to the drive circuit 11 . Therefore, the count value of the counter 2 is read by the drive circuit 11, converted into 8-segment information for each digit, and sent to the liquid crystal display 12. In this way, the amount of electric power up to the time of power outage is displayed on the liquid crystal display 2. - On the other hand, if the illuminance on the liquid crystal display 12 is low and the displayed weight value cannot be read, the optical switch 13 will not conduct and the backup voltage will turn off.
5 is not supplied to the drive circuit 11. Therefore, the display circuit 10 does not operate at all and consumes no power. At this time, the counter 2 holds the count value, ie, the amount of power, from when power is supplied until the time of power outage. Note that when the power outage is restored, power is supplied from the AC/DC conversion power source 4 to the power-frequency conversion circuit 1, counter 2, and display circuit 10, and immediately after this, power supply from the backup power source 5 is stopped.

In this way, in the above-mentioned example, power is supplied from the backup power supply 5 to the counter 2 and the display circuit 10 during a power outage, and at this time, the optical switch 13 provided near the liquid crystal display surface of the display circuit 10 is used to display the display. If the illuminance is such that the meter tii can be read, the backup power source 5 is connected to the display circuit 1o, so the amount of electric power can be reliably read only in the case of illuminance that requires reading the display meter n value.
In the case of other illuminances, the display circuit 1o is not operated, thereby eliminating wasteful consumption of the backup power source 5.

In particular, the power supply period to the drive circuit 11 that consumes the most power during a power outage becomes elongated, and the Q power output is significantly reduced. Therefore, if the backup power supply 5 can be used for a long period of time, and if the battery of the backup power supply 5 is replaced every -W1, the battery capacity can be reduced compared to the conventional watt-hour meter. It can be made smaller and smaller. In this way, even in the case of electronic electric energy, it is possible to maintain electric power a for a long period of time until a power outage occurs, as with an inductive electric power meter having a mechanical register mechanism, and to display the electric energy only when necessary. Also, by using the optical switch 13, the display meter ff1r
No need to operate a switch etc. to read Ii.
Furthermore, problems such as contact wear are eliminated, and reliability can be improved.

Note that the present invention is not limited to the above-mentioned embodiment, and may be modified without departing from the spirit thereof. For example, the optical switch 13 may use a photodiode or a photocell. Furthermore, the signal when the optical switch 13 is turned on can also be used as an initial reset signal for the liquid crystal display 12.

Furthermore, it is applicable not only to electronic wattmeters but also to electronic reactive wattmeters, power factor meters, and the like.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide an electronic measuring instrument that can perform a display operation only when reading is possible at a predetermined illuminance, thereby eliminating wasteful consumption of backup power.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the case where the electronic meter according to the present invention is applied to an electronic watt-hour meter, and FIGS. 2 and 3 are block diagrams of conventional electronic meters. be. 1... Power-frequency conversion circuit, 2... Counter, 4
... AC/DC conversion power supply, 5... Pack-up power supply, 10... Display circuit, 11... Drive circuit, 12.
...Liquid crystal display, 13...light switch. Figure 1 Figure 2

Claims (1)

[Claims] In an electronic measuring instrument that measures an amount of electricity, etc., there is a backup power supply that supplies power to the measurement value holding circuit and display circuit in the event of a power outage; An electronic measuring instrument comprising: a display switch control element that detects that illuminance is readable and connects the backup power source to the display circuit.