JP4788133B2 - Power circuit - Google Patents

Description

  The present invention relates to a power supply circuit used in an electronic device.

  2. Description of the Related Art Conventionally, in an electronic device operating with a commercial AC power supply, a power supply circuit 101 including a switching power supply circuit (switching regulator) having a configuration as shown in FIG. Is used. The power supply circuit 101 uses a commercial AC input 102 input from an AC outlet as a power source, which is converted into a pulsating current by an input rectifier bridge (diode) 103 and then converted into a direct current including ripples by an input capacitor 104. If the commercial power supply voltage is 100V, the input capacitor 104 outputs a peak voltage of about 140V. In the power supply circuit 101, the high voltage is stepped down to a low voltage (DC 5V to 2.5V for IC) used in an electronic device or a predetermined voltage (for example, DC 12).

  The circuit after the input capacitor 104 is a so-called switching power supply circuit 114, which is a “forward converter”. Here, the input direct current voltage is converted into a high-frequency alternating current by the on / off operation of the switching element 106 under the control of the control IC 105. The AC power is input to the primary side of the transformer 107, and a low voltage AC is generated on the secondary side. The secondary alternating current is again rectified by the diodes 108 and 109 and converted into direct current including a high frequency ripple voltage by the output choke 110 and the capacitor 111. Further, an error in the output voltage is detected by the variable shunt regulator 112, which is fed back to the primary side of the transformer 107 by the photocoupler 113 and input to the control IC 105. The constant voltage control on the secondary side is performed by controlling the switching time of the switching element 106 by this feedback voltage.

This type of power supply circuit is also described in, for example, Patent Document 1 below.
JP 2001-178125 A

  However, in the power supply circuit 101 as described above, the DC voltage after being rectified by the input rectification bridge 103 and smoothed by the input capacitor 104 is supplied to the voltage switching power supply circuit 114, so A ripple voltage is applied to the side, and the peak value varies depending on the load on the secondary side. Since the ripple voltage is transmitted to the secondary side, the output voltage on the secondary side varies. FIG. 5 is a diagram showing fluctuations of the primary side DC voltage (a) and the output voltage (b) when the voltage of the input capacitor 104 is 140V and the output voltage is 5V.

  Here, the voltage drop time in the ripple voltage input to the primary side of the switching power supply circuit 114 and the output voltage drop time detected on the secondary side of the switching power supply circuit 114 are synchronized with each other. The time when the stored electric power is used to stabilize the output voltage coincides with the time when the input voltage to the input capacitor 104 decreases. That is, in the power supply circuit 101, the output voltage stabilization operation is a circulation in a direction in which the amount of periodic drop of accumulated charge in the input capacitor 104 is increased.

  Therefore, there is a problem that it is indispensable to use a large-capacity capacitor as the input capacitor 104 in order to eliminate the ripple noise and stabilize the output voltage.

  The present invention has been made in view of such conventional problems, and it is possible to obtain a stable output voltage without providing a large-capacitance capacitor and without reducing the efficiency of use of power supplied from a power source. An object of the present invention is to provide a power supply circuit that can be used.

In order to solve the above-mentioned problem, in the invention of claim 1, a primary side voltage, which is provided in an electronic device and includes an AC component due to electric power supplied from a first power source, is converted into a predetermined voltage to obtain a secondary voltage. In the power supply circuit including the voltage conversion unit that outputs to the side, the second independent power converted from the thermal energy or the light energy different from the first power source generated during operation inside the electronic device to the electrical energy A stabilization control unit for stabilizing the output voltage on the secondary side of the voltage conversion unit using power supplied from a thermoelectric conversion element or a photoelectric conversion element as a power source is provided.

Further, in the invention of claim 2, the stabilization control unit generates a reference voltage serving as a reference for stabilizing the output voltage on the secondary side of the voltage conversion unit, and An output fluctuation detecting unit that compares the reference voltage generated by the reference voltage generating unit with an output voltage on the secondary side of the voltage converting unit; and an electric power supplied from the second power source is the voltage converting unit. And an addition control unit that controls the power addition unit so as to stabilize the output voltage on the secondary side of the voltage conversion unit.
According to a third aspect of the present invention, the stabilization control unit is stabilized by a voltage stabilization unit for stabilizing the power output from the second power source, and the voltage stabilization unit. And a second voltage converter that converts the converted output voltage.
Further, in the invention of claim 4, wherein the addition control section controls the power adding section to the power supplied is added to the primary side of the voltage conversion unit from said second power source It was.

Further, in the invention of claim 5, wherein the addition control section controls the power adding section to add a power supplied from the second power source to the secondary side of the voltage conversion unit It was supposed to be.

In the invention of claim 6, the second power source is a DC voltage source that converts thermal energy or light energy generated during operation inside the electronic device into electrical energy.

In the invention of claim 7 , the DC voltage source is a thermoelectric conversion element that converts thermal energy generated during operation inside the electronic device into electrical energy.

In the invention of claim 8 , the DC voltage source is a photoelectric conversion element that converts light energy generated during operation inside the electronic device into electric energy.

According to the ninth aspect of the present invention, the primary side voltage, which is provided in the projector apparatus having the projection lamp and includes the AC component by the power supplied from the first power source, is converted into a predetermined voltage. In a power supply circuit including a voltage conversion unit that outputs to the next side, an independent second converted from electrical energy to thermal energy or light energy that is different from the first power source generated during operation inside the electronic device . And a stabilization control unit that stabilizes the output voltage on the secondary side of the voltage conversion unit using the power supplied from the power source.

In the invention of claim 10 , the projection lamp is lit by power supplied from the secondary side of the voltage converter, and the second power source is accompanied by the lighting of the projection lamp. The thermoelectric conversion element converts the generated heat into electric energy.

  As described above, in the power supply circuit of the present invention, it is possible to obtain a stable output voltage without providing a large-capacitance capacitor and without reducing the efficiency of using the power supplied from the first power source. It becomes. In addition, the power supplied from the first power source can be effectively used, and the power of the second power source can be easily supplied to the primary side or the secondary side of the voltage converter.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration example of a projector 1 including a power supply circuit 3 according to the present invention. In the projector 1, the commercial alternating current (AC) voltage supplied from the outlet via the power cord 2 is converted into a predetermined direct current (DC) voltage by the power supply circuit 3, and the main circuit (video processing circuit) of the projector 1 is converted. And control circuit 4). The main circuit 4 mainly drives a transmissive liquid crystal panel 5 that is an image conversion element (also referred to as a light modulation element) based on video or image signals input from a personal computer or the like, or uses power supplied from the power supply circuit 3. The lighting and extinguishing of the projection lamp 6 are controlled. During the projection operation, the light L1 emitted from the projection lamp 6 is transmitted through the liquid crystal panel 5, and the transmitted light L2 is irradiated onto the screen S via the condenser lens 7 and the projection lens 8, thereby causing an optical image (on the screen S). A moving image or a still image) is projected.

  On the other hand, a thermoelectric conversion element 9 is arranged in the vicinity of the projection lamp 6 in the housing of the projector 1 (not shown). When the thermoelectric conversion element 9 has a temperature difference between two contact points of different metals in the same circuit, the projection lamp 6 is turned on based on the Seebeck effect in which a voltage is generated between the contact points. This is a DC voltage source (second power source) of the present invention that converts generated heat into electric energy and supplies the electric energy, that is, thermoelectromotive force, to the power supply circuit 3. Further, on the opposite side of the surface of the thermoelectric conversion element 9 that faces the projection lamp 6, a fin 10 for heat dissipation (cooling) is attached to improve the thermoelectric conversion efficiency by ensuring a larger temperature difference between the two surfaces. It has been.

  FIG. 2 is a block diagram showing a schematic configuration of the power supply circuit 3 including the thermoelectric conversion element 9. In the figure, a portion indicated by a broken line corresponds to the conventional power supply circuit 101 shown in FIG. 4 and is an alternating current (AC) voltage supplied via the power cord 2, that is, the commercial AC input 102 described above. The (first power source) is converted into a pulsating flow by the input rectifier bridge 103, converted to a direct current including ripples by the input capacitor 104, and then stepped down to a predetermined voltage by the switching power supply circuit 114 ( (See FIG. 4). The switching power supply circuit 114 is a voltage conversion unit of the present invention.

  Further, the power supply circuit 3 includes the voltage stabilizing circuit 11, the voltage converting circuit 12, the voltage adding circuit 13, the error detecting / controlling circuit 14, and the reference voltage circuit 15 that constitute the stabilizing control unit of the present invention. ing.

  The voltage stabilization circuit 11 is a circuit for stabilizing the voltage of the power output from the thermoelectric conversion element 9 described above. The voltage conversion circuit 12 is a circuit that converts (boosts) the output voltage from the voltage stabilization circuit 11 into a voltage after rectification and smoothing, that is, an input voltage on the primary side of the switching power supply circuit 114. The voltage addition circuit 13 is a power addition unit of the present invention, and is controlled by the error detection / control circuit 14 and also supplies power supplied from the voltage conversion circuit 12 between the input capacitor 104 and the switching power supply circuit 114 (switching power supply). It is applied as supplementary power to the primary side of the circuit 114. The voltage adding circuit 13 is configured by, for example, a switching FET (field effect transistor).

  The reference voltage circuit 15 is a circuit that generates a reference voltage for stabilizing the output voltage on the secondary side of the switching power supply circuit 114 and supplies the reference voltage to the error detection / control circuit 14. Note that the reference voltage circuit 15 can substitute the variable shunt regulator 112 described above in the switching power supply circuit 114. The error detection / control circuit 14 is an output fluctuation detection unit of the present invention, which compares the output voltage on the secondary side of the switching power supply circuit 114 with the reference voltage output from the reference voltage circuit 15, and determines the difference, that is, ripple noise. A variation amount (error with respect to the reference voltage) is detected, and supplementary power corresponding to the detected amount (error amount) is output from the voltage addition circuit 13. That is, the supplementary power is increased or decreased by negative feedback control.

  In the power supply circuit 3 described above, a ripple voltage is generated in the DC voltage on the primary side of the switching power supply circuit 114, and even if the peak value fluctuates due to the load on the secondary side, it is shown in FIG. As described above, the supplementary power component Ea corresponding to the change on the secondary side is always added to the DC voltage on the primary side, so that the output voltage on the secondary side is stabilized as shown in FIG. It will be. 3 is an example in which the voltage of the input capacitor 104 is 140 V and the output voltage is 5 V, as in FIG.

  Therefore, a more stable output voltage can be obtained without using a large-capacity capacitor for the input capacitor 104. Moreover, since the supplementary power is supplied from the thermoelectric conversion element 9 separately from the commercial AC input 102, the use efficiency of the power supplied from the power source on the secondary side of the switching power supply circuit 114 is not reduced. The output voltage can be stabilized. Further, the supplementary power is obtained by converting the heat generated inside the projector 1 by the thermoelectric conversion element 9 as the projector 1 is moved, so that the power of the commercial AC input 102 can be used more effectively. Moreover, since the thermoelectric conversion element 9 is a DC power source, the electromotive force can be easily used as the supplementary power.

  In the present embodiment, an example in which the output voltage on the secondary side is stabilized by adding the electric power obtained by the thermoelectric conversion element 9 to the primary side of the switching power supply circuit 114 is shown. The output voltage on the secondary side may be stabilized by adding the power to the secondary side of the switching power supply circuit 114, for example, the secondary-side capacitor 111 (see FIG. 4) described above. In addition, the supplementary power is added to the primary side by negative feedback control according to the error of the output voltage on the secondary side, but the fluctuation amount of the input voltage on the primary side is detected, and the supplementary power is changed according to the fluctuation amount. It can also be controlled.

  The place where the thermoelectric conversion element 9 for obtaining supplementary power is disposed may be any place as long as it is in the vicinity of the projection lamp 6, and a plurality of thermoelectric conversion elements 9 may be provided as necessary. In that case, as long as heat is generated when the projector 1 is operating, it may be provided, for example, near the transformer 107 (see FIG. 4) in the switching power supply circuit 114.

  Moreover, in this Embodiment, although the example which uses only the thermoelectric conversion element 9 as a 2nd electric power source (DC voltage source) of this invention was shown, it supplements the electromotive force of the thermoelectric conversion element 9 not only to this. For example, a photoelectric conversion element such as a solar cell that converts light outside the housing of the projector 1 into electrical energy may be used.

  Furthermore, although the case where the power supply circuit of the present invention is used for a projector has been described in the present embodiment, the power supply circuit of the present invention is also effective when used for electronic devices other than a projector. Even in that case, the thermoelectric conversion element 9 or the photoelectric conversion element described above can be used as the second power source. Furthermore, it may not be a DC voltage source such as a thermoelectric conversion element or a photoelectric conversion element.

It is a block diagram which shows the structural example of the projector which concerns on this invention. It is a block diagram which shows schematic structure of the power supply circuit of the projector. It is the figure which showed the primary side input voltage (a) to which the supplementary electric power component in the same power supply circuit was added, and the secondary side output voltage (b). It is a figure which shows the conventional power supply circuit. It is the figure which showed the primary side input voltage (a) containing the ripple noise in the same power supply circuit, and the secondary side output voltage (b).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projector 2 Power supply code 3 Power supply circuit 4 Main body circuit 5 Liquid crystal panel 6 Projection lamp 7 Condenser lens 8 Projection lens 9 Thermoelectric conversion element 10 Fin 11 Voltage stabilization circuit 12 Voltage conversion circuit 13 Voltage addition circuit 14 Error detection / control circuit 15 Reference voltage circuit 101 Power supply circuit 102 Commercial AC input 103 Input rectifier bridge 104 Input capacitor 112 Variable shunt regulator 114 Switching power supply circuit Ea Supplementary power component

Claims (10)

In the power supply circuit provided with the voltage conversion unit provided in the electronic device, which converts the primary side voltage including the AC component by the power supplied from the first power source into a predetermined voltage and outputs it to the secondary side.
Supplied from a thermoelectric conversion element or photoelectric conversion element, which is an independent second power source converted into electrical energy from thermal energy or light energy different from the first power source generated during operation inside the electronic device. A power supply circuit comprising: a stabilization control unit that stabilizes an output voltage on the secondary side of the voltage conversion unit using power to be output. The stabilization control unit includes:
A reference voltage generation unit that generates a reference voltage that serves as a reference for stabilizing the output voltage on the secondary side of the voltage conversion unit;
An output fluctuation detector that compares the reference voltage generated by the reference voltage generator with the output voltage on the secondary side of the voltage converter;
A power adding unit for adding power supplied from the second power source to the voltage conversion unit in a time-sharing manner by a switching unit;
An addition control unit for controlling the power addition unit so as to stabilize the output voltage on the secondary side of the voltage conversion unit;
The power supply circuit according to claim 1, comprising: The stabilization control unit includes:
A voltage stabilizing unit for stabilizing the power output from the second power source;
A second voltage converter that converts the output voltage stabilized by the voltage stabilizer;
The power supply circuit according to claim 1, further comprising:   4. The power supply according to claim 2, wherein the addition control unit controls the power adding unit to add power supplied from the second power source to a primary side of the voltage converting unit. 5. circuit.   The said addition control part controls the said electric power addition part so that the electric power supplied from a said 2nd electric power source may be added to the secondary side of the said voltage conversion part, The Claim 2 or 3 characterized by the above-mentioned. Power supply circuit. The said 2nd electric power source is a DC voltage source which converts the thermal energy or optical energy which arises in operation inside an electronic device into an electrical energy, The any one of Claims 1-5 characterized by the above-mentioned. Power supply circuit. Said DC voltage source, the power supply circuit of claim 6 Symbol mounting, characterized in that a thermoelectric conversion element for converting the thermal energy generated due to the operation inside the electronic device into electrical energy. Said DC voltage source, the power supply circuit of claim 6 Symbol mounting, characterized in that a photoelectric conversion element for converting light energy produced due to the operation inside the electronic device into electrical energy. A power supply provided with a voltage conversion unit that is provided in a projector device having a projection lamp and converts a primary side voltage including an AC component by power supplied from a first power source into a predetermined voltage and outputs the voltage to a secondary side. In the circuit
The voltage conversion unit using electric power supplied from an independent second power source converted into electrical energy from thermal energy or light energy different from the first power source generated during operation inside the electronic device A power supply circuit comprising: a stabilization control unit that stabilizes the output voltage on the secondary side. The projection lamp is lit by power supplied from the secondary side of the voltage converter,
10. The power supply circuit according to claim 9, wherein the second power source is a thermoelectric conversion element that converts heat generated when the projection lamp is turned on into electric energy.

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