JPS62229691A - Lighting apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

The present invention generally relates to a lighting device, and more particularly to a lighting device equipped with a light emitting means such as a fluorescent lamp that emits light by an electromagnetic field generated by receiving supplied high frequency power.

Various types of light emitting means used in lighting devices have been researched and developed, but in recent years the use of fluorescent lamps has become common from the perspective of energy saving. That is, for example, when comparing a fluorescent lamp and a general halogen lamp, the illuminance of a fluorescent lamp is generally on the order of 60 to 701 m/W, and the illuminance of a general halogen lamp is 20 to 30 m/W.
Compared to 1 m/W, the illuminance per IW is large and the efficiency is good. Fluorescent lamps also emit less heat to the surroundings than halogen lamps, and have many design advantages.For this reason, fluorescent lamps are often used as a general lighting method in homes and offices, etc. BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND ART BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION As a light source for exposure in copying machines such as electrophotographic copying machines. Conventionally, when using a fluorescent lamp as a light source for exposure in a copying machine etc. as mentioned above,
For example, a lamp with power consumption on the order of 20 to 30 W is selected, and the oscillation frequency in the lighting circuit when lighting such a fluorescent lamp is set on the order of 40 to 50 KHz, and the oscillation frequency at both ends of the fluorescent lamp is set on the order of 40 to 50 KHz. The applied voltage is set to be on the order of several hundred volts. By the way, copying machines such as the electrophotographic copying machine mentioned above,
When using a fluorescent lamp as a light source for exposure, it has become necessary to increase the amount of exposure per unit time as a document reading light source in response to recent technical demands for faster copying speeds for copying machines. It's coming. In addition, the amount of light emitted by the fluorescent lamp itself used as a light source for exposure may be affected by the blackening of the fluorescent lamp due to the evaporation and scattering of electron emitting substances from the filament installed in the fluorescent lamp, or the breakage of the filament itself. There were problems such as a decrease in the temperature over time or a shortened lifespan. Therefore, in an attempt to solve these technical problems, a device was devised that removes the filament installed inside the fluorescent lamp and applies high voltage directly to both ends of the fluorescent lamp from the outside to generate a discharge. 5 shows an outline of such a device, and as is clear from FIG. 2 is driven to generate high-frequency oscillation (for example, sine wave oscillation), and the high-frequency oscillation output from the drive circuit 2 is transmitted to electrodes disposed on the outer walls of the fluorescent lamp 5 at both ends, for example, through a low-loss power supply l13. By applying an electric current to a conductive wire electrode 4 formed by winding a conductive wire, a discharge is generated between the conductive wire electrodes 4, causing the fluorescent lamp 5 to emit light.The fluorescent lamp 5 having the above-described configuration Since a filament is not required to cause the fluorescent lamp 5 to emit light, there is no restriction on drive voltage or current due to the presence of a filament, and the degree of freedom in design increases accordingly. The amount of light emitted from the fluorescent lamp 5 can be increased because the voltage applied to the fluorescent lamp 5 and the magnitude of the supplied current can be freely set. By the way, if we show the specific means necessary to control the amount of light emitted from the fluorescent lamp 5 in the device shown in FIG. That is, according to FIG. 6, a DC power supply (for example, on the order of about 12 V DC) 6 corresponding to the drive power supply 1 described above supplies DC power to the oscillation section 7 constituting the drive circuit 2, and performs oscillation. The unit 7 receives power from the DC power supply 6 and is driven to generate high frequency oscillation (for example, on the order of 10MHz). A discharge is generated in the fluorescent lamp 5 by receiving the high frequency oscillation output from the oscillation unit 7 and boosting the voltage to the order of several KVp-p and applying the high frequency and high voltage to the conductive wire electrode 4 described above. An analog signal indicating the amount of light emitted from the fluorescent lamp 5 provided via the light amount sensor 9 and the light amount detecting portion lO1 integrator 11, which together with the D converter 12 and the control unit 13 constitute the aforementioned control system, is sent to the A/D converter. 12 and provided to the control section 13, the control section 13 applies PWM (pulse width variation) to the switching element 140 interposed between the oscillation section 7 and the boost section 8 based on the signal. rR)
A signal is applied to control the switching operation of the switching element 140 to adjust the amount of light emitted from the fluorescent lamp 5 so as to always maintain it at a predetermined amount. However, in the configuration shown in FIG. 6, it is necessary to apply a high frequency voltage of several KVP-P, lOMHz to the fluorescent lamp 5, so
This requires a drive system for high-frequency voltages on the order of MHz, and controlling such a drive system is technically much more difficult than controlling the drive system of a fluorescent lamp using a normal commercial power source. As mentioned above, in the so-called duty ratio (impact coefficient) control in which the control section 13 controls the switching operation of the switching element 140 using a PWM signal to control the amount of light emitted from the fluorescent lamp 5, the normal commercial frequency is used. Unlike the light emission amount control of a fluorescent lamp when using the booster section 8, the drive current is large and the surge voltage during transients caused by the actance of the coil that constitutes the booster section 8 is also high, so the effect on the drive system is large. This results in accelerated deterioration of the entire device, and has the disadvantage that the above-mentioned high surge voltage adversely affects the life of the fluorescent lamp 5. Furthermore, there was also a problem that noise generated by controlling the duty ratio of the high voltage of several KVP-P mentioned above was emitted to the surroundings. ■ Therefore, the present invention was devised to improve the shortcomings and inconveniences of the conventional technology as described above, and its purpose is to drive a power source with a much higher frequency and voltage than a normal commercial power source. Even when used for The object of the present invention is to provide a lighting device that can be controlled to a specific value. . - The above object is achieved by a lighting device according to the present invention. In summary, the present invention provides a light emitting means that receives high frequency power to generate an electromagnetic field and generates light by the generated electromagnetic field, and a high frequency power feeding means that outputs high frequency power for driving the light emitting means. and a control means for controlling driving of the high-frequency power feeding means according to the detected amount of light emitted from the light-emitting means. An impedance matching means whose output impedance is variable is provided, and the control means matches an impedance value in the impedance matching means with an impedance value in the light emitting means based on the amount of light emitted from the light emitting means. This lighting device is characterized in that it is configured so that it can be adjusted as follows. Support 11 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a lighting device according to an embodiment of the present invention, and as is clear with reference to FIG. a fluorescent lamp 5 and an electromagnetic field generating means, that is, an electromagnetic field generating section 27, a drive circuit 2 as a high frequency power feeding means as a drive system that supplies driving power to the fluorescent lamp 5, and a control means, that is, a control section 13. In the configuration, the impedance matching unit 25, which is capable of variable adjustment of impedance by the control unit 13, is connected to the drive circuit 2.
The configuration is such that it is interposed between the output side of the electromagnetic field generator 27 and the electromagnetic field generating section 27. The drive circuit 2 described above includes an LC oscillation circuit, and a high-frequency oscillation section 7 that receives power from a DC power supply 6 and outputs high-frequency power of about 5 to IOW at an oscillation frequency on the order of, for example, IOMHz. , and a high-frequency amplification section 18 that receives the high-frequency power output from the high-frequency oscillation section 7, amplifies it to about 200 W, and outputs the amplified power. The fluorescent lamp 5 has the above-mentioned electromagnetic field generating section 27 on the outside thereof.
When a magnetic field is generated in the electromagnetic field generating section 27, the internal electrons are accelerated by the generated magnetic field, Hg is excited, and a discharge is generated, thereby emitting light. The electromagnetic field generating section 27 includes a φ2. A coil made by winding a 0mm nichrome wire multiple times in a ring shape is used, and receives the high frequency power output from the high frequency amplification section 18 through the impedance matching section 25 described above, and uses electromagnetic induction to power the fluorescent lamp. 5 to generate a magnetic field. The control system centered on the control section 13 described above includes a control section 13 and a photocell, which is disposed near the fluorescent lamp 5 and detects the amount of light emitted from the fluorescent lamp 5. connected to the sensor 9 and the input side of the control unit 13;
A light amount detection section 10 that converts the optical signal from the light amount sensor 9 into a current signal, an integrator 11 that converts the current signal from the light amount detection section 10 into a voltage signal, and an A/D that digitizes the voltage signal from the integrator 11. Input section 22 consisting of converter 12
and an output section that is connected between the output side of the control section 13 and the impedance matching section 25 and includes a decoder 15 that receives an output signal from the control section 13, and a driver 16 that receives the output signal from the decoder 15. 20.20. The control unit 13 is composed of a CPU 130 that performs arithmetic and logical operations, and a ROM 131 that stores in advance digital data regarding the appropriate light amount of the fluorescent lamp 5, for example, the maximum light amount as described later.
U130 calculates a difference value between the detection value data provided from the light amount sensor 9 via the input unit 22 and the digital data, and outputs a predetermined signal to the output unit 20.20 according to the difference value, The combined impedance of the impedance matching section 25 is adjusted so that the detected value data provided from the light amount sensor 9 matches the data stored in the ROM 131. The internal configuration of the impedance matching section 25 described above is as shown in FIG. 2, for example. That is, as is clear with reference to FIG. 2, the impedance matching section 25 according to one embodiment of the present invention includes a high voltage capacitor Co
37, C'o to C'n38 and switching element 5o
-5n39, S'. ~S''n40 are connected in a matrix.The high voltage capacitor C. ~Cn37 and C'o-C''n38 have a frequency characteristic with a withstand voltage of the order of 3KV, for example. A high voltage capacitor with excellent low loss is used. Switching elements with small contact capacitance and high withstand voltage are used for the switching elements S o to S n 39 and S"o-3' n40, and each of these switching elements 5oNSn3
9. S”o-3”n40 is the driver 16.1 mentioned above.
6 and decoder 15.15, the high voltage capacitors 5o-3n37 and S'o-3'n38
The composite impedance of the impedance matching section 25 formed between the two is made variable. Next, by interposing the impedance matching section 25 having the above-described configuration between the output side of the drive circuit 2 and the electromagnetic field generating section 27 and variably adjusting the composite impedance in the impedance matching section 25, the fluorescence The reason why it is possible to control the amount of light emitted from the lamp 5 to a desired value (ie, the maximum value of the amount of light emitted) will be explained. As illustrated in FIG. The input impedance of the electromagnetic field generating section 27 and the fluorescent lamp 5, which are loads of the drive circuit 2, viewed from the drive circuit 2 side through the impedance matching section 25 is set to 201, and the input impedance of the drive circuit z side viewed from the load side, i.e. Impedance matching section 2
If the output impedance of 5 is 202, ZO1=Z
It is a well-known fact that maximum power is supplied from the drive circuit 2 to the load side only when the O2 relationship holds, that is, when the input impedance and output impedance match. That is, if the input impedance Z01 on the load side described above is a constant value, the power supplied from the drive circuit 2 to the load can be greatly varied by varying the output impedance Z02 on the drive circuit 2 side, and This tendency becomes more pronounced as the frequency increases, as in the case of lighting the fluorescent lamp 5 at a high frequency of 10 MHz as in the embodiment. FIG. 4 shows the fluctuation of the power supplied to the load side when the output impedance Z02 of the impedance matching section 25 is varied, and the vertical axis shows the value of the power P (W), and the horizontal The axes represent the value of the output impedance ZO2 in the impedance matching section 25, the curve ii Po represents the value of the power supplied from the drive circuit 2, and the curve P' represents the input impedance Z01 on the load side and the impedance matching section 25. Side output impedance Z0
The curve P″ shows the value of the reactive power loss reflected from the load side when there is a mismatch between . Point A set on the horizontal axis described above indicates the value of ZO2 when it matches Zol. As is clear with reference to FIG. 4, when the value of ZO2 is point A, that is, zoi=
It can be seen that the value of P'' is maximum when zO2. Therefore, in one embodiment according to the present invention as described above, the value of the output impedance 202 in the impedance matching section 25 is as shown in FIG. The value P'' of the power actually supplied to the load when it matches the value at point A shown in the diagram
The light amount value data at the time of layer ax is stored in the ROM 131 in advance, and the detected value data output from the light amount sensor 9 and inputted to the control section 13 via the input section 22 is the P''■
CPU 13 so that it matches the light amount value data at the time of aX.
By variably adjusting the combined impedance in the impedance matching section 25, it is possible to supply maximum power to the load side, and therefore the amount of light emitted from the fluorescent lamp 5 can be adjusted to the maximum. Below, the operation of variable adjustment of the composite impedance of the impedance matching section 25 in the lighting device according to an embodiment of the present invention will be described. From the light amount sensor 9 to the input section 22
When data indicating the amount of light emitted from the fluorescent lamp 5 is input to the CPU 130 via and outputs a control signal to the output section 20.20 so that the difference value becomes O. As a result, the switching element 5
o-3n39 and S'o-3'n40 perform switching operations. For example, the C
Switching element So according to a control signal given from PU130. S,, Sz・Fist・5n39 and switching element S'o4
In the case where only the high voltage capacitor 0 performs a closing operation, the combined impedance in the impedance matching section 25 is the combined capacitance of the high voltage capacitor Co, C1Φ-fist・Cn37 in series, and the parallel combined capacitance of the high voltage capacitor Co37 and high voltage capacitor C'o38. It will be determined by the combined capacity. By variably adjusting the value of the composite impedance Z02 in the impedance matching section 25 in this way, when the value of the composite impedance Z02 matches the value of point A shown in FIG. Since the electric power is given to the electromagnetic field generator 27, the amount of light emitted from the fluorescent lamp 5 reaches the maximum value, and as a result, the detected value data and the ROM 131 are given from the light amount sensor 9 to the CPU 130 via the input section 22. As described above, according to the lighting device according to the embodiment of the present invention, the impedance matching unit 25 is controlled by the control signal output from the control unit 13. Since the composite impedance is variably adjusted in
Since the value of the composite impedance Z02 can be freely varied by simply varying the control signal applied to the o-5'n40, the high-voltage capacitors Co, C1...37, C'0, C
It is possible to widen the variable range of the value of the composite impedance Z02 without increasing the number of 'Zφ C'n38. The content explained above is only related to one embodiment of the present invention, and does not mean that the present invention is limited only to the above content. Alternatively, the impedance matching section 25 may be configured using a coil, or the impedance matching section 25 may be configured using a combination of a high voltage capacitor and a coil. In this embodiment, a φ2. We decided to use a coil made by winding a 0mm nichrome wire multiple times in a ring shape, but the electromagnetic field was generated using electrodes placed on the outer wall at both ends of the fluorescent lamp 5 as shown in Figures 5 and 6. There is no problem even if it is used as a part. 11. As explained above, according to the present invention, impedance matching means is provided on the output side of the high-frequency power feeding means, and the output impedance of the high-frequency power feeding means can be varied, and the control means controls the light emission. The impedance value in the impedance matching means can be adjusted based on the amount of light emitted from the means so that the impedance value matches the impedance value in the light emitting means. Even if a much higher frequency and higher voltage power source is used as the drive power source, there is no risk of accelerating the deterioration of the device as a whole, there is no risk of adversely affecting the lifespan of the light source, and there is no risk of emitting noise to the surroundings. It is possible to provide a lighting device that can control the amount of light emitted from a light source to a desired value without such problems.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a lighting device according to an embodiment of the present invention. FIG. 2 is a block diagram showing the internal configuration of an impedance matching section applied to a lighting device according to an embodiment of the present invention. FIG. 3 is a diagram showing the mutual relationship between the output impedance on the drive circuit side and the input impedance on the load side in a lighting device according to an embodiment of the present invention. FIG. 4 is a diagram showing a characteristic curve representing the relationship between the power supplied to the load and the value of the composite impedance in the impedance matching section according to one embodiment of the present invention. FIG. 5 is a block diagram showing a lighting device according to the prior art. FIG. 6 is a block diagram showing details of the configuration of the lighting device shown in FIG. 5. 2: Drive circuit 5: Fluorescent lamp 13: Control section 25: Impedance matching section 27: Electromagnetic field generation section Fig. 2 Fig. 3 Fig. 4 Inevitability

Claims (1)

[Scope of Claims] 1) A light-emitting device that receives high-frequency power to generate an electromagnetic field and generates light by the generated electromagnetic field, and a high-frequency device that outputs high-frequency power to drive the light-emitting device. In a lighting device comprising a power feeding means and a control means for controlling driving of the high frequency power feeding means according to the detected amount of light emitted from the light emitting means, the high frequency power feeding means is connected to the output side of the high frequency power feeding means. An impedance matching means whose output impedance on the means side is variable is provided, and the control means adjusts the value of impedance in the impedance matching means based on the amount of light emitted from the light emitting means to the value of the impedance in the light emitting means. A lighting device characterized in that it is configured to be adjustable so as to match the lighting device. 2) The light emitting means includes an electromagnetic field generating means that generates an electromagnetic field by receiving power from the high frequency power feeding means, and a fluorescent lamp that emits light by the electromagnetic field generated by the electromagnetic field emitting means. Claim 1 characterized by
The lighting device described in Section 1. 3) The electromagnetic field generating means has a diameter of 2.0 mm on the outer wall of the fluorescent lamp.
3. The illumination device according to claim 2, characterized in that the lighting device is made by winding a nichrome wire having a diameter of 1.5 mm in a plurality of turns in a ring shape. 4) The lighting device according to claim 2, wherein the electromagnetic field generating means comprises electrodes disposed on outer walls at both ends of the fluorescent lamp. 5) The high-frequency power feeding means includes a high-frequency power generation means that receives DC power supplied from a DC power supply and generates high-frequency power, and a high-frequency power amplification that receives and amplifies the high-frequency power output from the high-frequency power generation means. An illumination device according to any one of claims 1 to 4, characterized in that it comprises means. 6) The impedance matching means is composed of a plurality of capacitance elements and a plurality of switching elements connected in a matrix that perform switching operations according to control signals output from the control means, and the impedance matching means is configured to have a plurality of capacitance elements and a plurality of switching elements connected in a matrix in response to a control signal output from the control means. Claims 1 to 5 are characterized in that the combined capacitance of the impedance matching means as a whole can be varied by switching each of the switching elements in response to a signal. A lighting device according to any of the sections. 7) The impedance matching means is composed of a plurality of inductive elements and a plurality of switching elements that perform switching operations according to the control signals output from the control means, connected in a matrix, and the impedance matching means is configured to control the control output from the control means. Claims 1 to 5 are characterized in that the combined induction amount of the impedance matching means as a whole can be varied by switching each of the switching elements in response to a signal. The lighting device described in any of the above. 8) The impedance matching means is composed of a plurality of inductive elements, a capacitive element, and a plurality of switching elements that perform switching operations according to a control signal output from the control means, which are connected in a matrix shape, Claims 1 to 3 are characterized in that the combined impedance of the impedance matching means as a whole can be varied by switching each of the switching elements in response to a control signal given to the impedance matching means. The lighting device according to any one of Item 5.