JP2003329714A - Power detection circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power detection circuit which suppresses a loss due to a resistance for current detection inserted in a line used to make mainly a current flow and whose power detection accuracy is high. <P>SOLUTION: As a detection method for a power consumption of a set, a tertiary winding is added newly in addition to a primary winding and a secondary winding of a power transformer, a voltage of the secondary winding is stabilized, a voltage change generated in the tertiary winding due to its load fluctuation is detected, and a power detection suppressing a loss due to a current detection is realized. The power consumption is detected with high detection accuracy even when the power consumption is extremely different, in a state that the set is normally turned on and in a state that the set is turned off by a remote control operation so as to be on standby. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting power consumption in a display device having a display device such as a cathode ray tube or a liquid crystal panel.

[0002]

2. Description of the Related Art A conventional power detection circuit detects a power by inserting a resistance for current detection into a line on the primary side or a secondary side of a power supply transformer in which a current mainly flows to convert the current into a voltage. Was there. This method has problems such as a large loss of resistance for current detection.

[0003]

As described above, when a resistance for current detection is mainly inserted in a line through which a current flows, the loss due to this resistance is large, and the power loss in the detection circuit for displaying the power consumption is low. There was a problem of getting bigger.

In view of the above problems, the present invention mainly provides a power detection circuit which detects power consumption without inserting a resistance for current detection in a line in which a current flows and suppresses power loss for power consumption detection. To do.

Although the power consumption may be extremely different between the normal ON state of the set and the standby state when the set is turned off by the remote controller, even in this case, a power detection circuit for detecting the power consumption with high detection accuracy is provided. .

[0006]

In order to solve the above-mentioned problems, the power detection circuit of the present invention stabilizes the primary winding for supplying power to the secondary winding of the power transformer and the load side. It is configured to have a secondary winding having a feedback circuit for supplying a voltage, and a tertiary winding in which a voltage change appears due to load fluctuation of the secondary winding.

Further, in order to improve the detection accuracy when the power consumption is extremely different, the signal input level of the A / D converter is switched depending on the set state when the voltage change occurring in the tertiary winding is detected. It is configured like.

With this configuration, the power consumption is detected without inserting a resistor for current detection mainly in the line through which the current flows, and the power loss for the power consumption detection is suppressed.
Provided is a power detection circuit that detects power consumption with high detection accuracy even when the power consumption of a set is extremely different.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The power detection circuit according to claim 1 of the present invention supplies power to a secondary winding of a power transformer as a method of detecting the power consumption when detecting and displaying the power consumption. A secondary winding having a feedback circuit for supplying a stable voltage to the load side, and a tertiary winding in which a voltage change appears due to load fluctuation of the secondary winding. Since the power detection circuit can be realized without inserting a resistance for current detection mainly in the line through which the current flows, there is an effect that power loss for detecting power consumption can be suppressed.

Next, the power detection circuit according to claim 2 of the present invention is the power detection circuit according to claim 1, wherein
When detecting and displaying the power consumption, as a method of detecting the power consumption, the A / D converter that detects the voltage change of the tertiary winding and the voltage level of the signal input to the A / D converter are set. It is characterized by having a voltage level switching circuit that switches depending on the state, and power consumption may be extremely different between the normal ON state of the set and the standby state when turned off by the remote control, but even in this case It has an effect that the power consumption can be detected with high detection accuracy.

(Embodiment 1) Claim 1 of the present invention will be described below.
An embodiment of the invention described in 1. will be described with reference to FIG. 1 is a block diagram of a power detection circuit according to a first embodiment of the present invention.

In FIG. 1, 1 is a power transformer, 2,
3 and 4 are the primary winding, the secondary winding, and the tertiary winding of the power transformer 1, respectively. A switching element 5 such as a transistor generates an AC voltage in the secondary winding 3 by turning on and off a current flowing in the primary winding 2.

Reference numeral 6 is a diode, and 7 is a capacitor, which rectifies and smoothes the AC voltage generated in the secondary winding to convert the voltage at point (a) into a DC voltage. Reference numeral 8 is a load resistance whose resistance value changes depending on the set state. Further, 9 is a stabilizing circuit, and 10 is a control circuit for turning on / off the switching element 5.

For example, when the resistance value of the load resistor 8 decreases and the power consumption of the set increases, the voltage at point (a) tends to decrease, but this voltage fluctuation is detected by the stabilizing circuit 9 and the control circuit 10 detects By increasing the ON period of the switching element 5, the voltage of the secondary winding 3 is controlled to increase, and as a result, the voltage at point (a) is stabilized so as not to decrease. At this time, since the voltage across the tertiary winding 4 increases, the voltage at point (b) rectified and smoothed by the diode 11 and the capacitor 12 also increases.

That is, when the power consumption of the set increases, the voltage at the point (b) increases, and conversely, when the power consumption of the set decreases, the voltage at the point (b) decreases.

An A / D converter 13 converts the voltage change at point (b) from analog into digital data, inputs it to the microprocessor 14, and converts it into power data to detect the power consumption of the set. It becomes possible.

(Embodiment 2) Next, claim 2 of the present invention
An embodiment of the invention described in 1. will be described with reference to FIGS. FIG. 2 shows the variation range of the power consumption of a certain set.

In FIG. 2, it can be seen that the power consumption of a certain set is extremely different between the normal ON state and the standby state when the remote control is turned off.

FIG. 3 is a block diagram of a power detection circuit according to the second embodiment of the present invention. In FIG. 3, reference numeral 16 is a voltage level conversion block, and the level input to the AD converter 13 can be set by the division ratio of the resistor 17. Reference numeral 18 denotes a switching element, which is connected to H from the microprocessor 14.
By outputting an I or LOW signal, a short circuit or an open state is established. When the set is in the ON state, the switching element 18 is short-circuited, and when the set is in the standby state, the switching element 18 is opened to change the signal level input to the A / D converter 13. It is possible to detect the voltage with high accuracy in each state, and as a result, the accuracy of power detection is improved.

[0020]

As described above, according to the power detection circuit of the present invention, since the power detection circuit can be realized without inserting a resistor for current detection mainly in the line through which the current flows, the power consumption is detected. It is possible to provide a power detection circuit that suppresses the power loss of.

Further, it is possible to provide a power detection circuit capable of detecting the power consumption with high detection accuracy even when the power consumption is extremely different from the normal ON state and the standby state when the set is turned off by the remote controller.

[Brief description of drawings]

FIG. 1 is a block diagram of a power detection circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a range of change in power consumption of a set.

FIG. 3 is a block diagram of a power detection circuit according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a conventional power detection circuit.

[Explanation of symbols]

1 Power Transformer 2 Primary Winding of Power Transformer 1 3 Secondary Winding of Power Transformer 1 4 Third Winding of Power Transformer 1 5, 18 Switching Element 6, 11 Diode 7, 12 Capacitor 8 Load Resistance (Set Consumption (The resistance value changes according to the fluctuation of the electric power.) 9 Stabilizing circuit 10 Control circuit 13 A / D converter 14 Microprocessor 15 Current detection resistor 16 Signal level switching block 17 Resistor

Claims (2)

[Claims] 1. A circuit for detecting the power consumption of a cathode ray tube or a liquid crystal panel, wherein a primary winding for supplying power to a secondary winding of a power transformer and a stable voltage are supplied to a load side. A secondary winding having a feedback circuit,
A power detection circuit having a tertiary winding in which a voltage change appears due to a load change of the secondary winding. 2. A for detecting a voltage change of the tertiary winding
The power detection circuit according to claim 1, further comprising a / D converter and a voltage level switching circuit that switches a voltage level of a signal input to the A / D converter according to a set state.