JP2008052925A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a discharge lamp lighting device for stabilizing the quantity of lamp light even if a different synchronization signal for switching color/monochrome is inputted. <P>SOLUTION: In a control circuit 12 to which a synchronization signal (e) for color having a low frequency is supplied, the value of a DC voltage Vd that becomes the power supply of an inverter circuit 15 becomes lower and a voltage Va for driving a discharge lamp 100 becomes lower as compared with a case where a synchronization signal e' for monochromes is supplied. Conversely, in the control circuit 12 to which a synchronization signal e' is supplied, the DC voltage Vd becomes high and a drive voltage Vb becomes high. Although the drive voltage Va is low, there are a few omissions of a lamp current during an oscillation pause period due to the synchronization signal. Although a drive voltage Vb is high, there are many oscillation pause periods due to the synchronization signal and there are many omissions of the lamp current. With the control, the high voltage Vb for driving the discharge lamp 100 can be set to a value that is the same as Va, thus making the quantity of light in the discharge lamp constant upon input of different synchronization signals. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device for lighting an outer surface electrode type dielectric barrier discharge lamp in which a discharge medium mainly composed of a rare gas is enclosed.

A conventional discharge lamp lighting device for lighting a dielectric barrier discharge lamp reliably improves the light emission white balance of the image reading means by keeping the number of pulses of a lamp current having a repetitive waveform generated during one reading cycle. There is. (For example, Patent Document 1)
JP 2003-217886 A

  The technique of the above-described Patent Document 1 stops the oscillation of the circuit at regular intervals by a synchronization signal. Further, the period of the synchronization signal is changed by the image reading means. When the discharge lamp is driven based on this change, there is a problem that the lamp current pulse number fluctuates and the lamp light quantity changes.

  An object of the present invention is to provide a discharge lamp lighting device capable of stabilizing the lamp light amount substantially constant even when different synchronization signals are input.

  In order to solve the above-described problems, a discharge lamp lighting device according to the present invention is disposed on the inner or outer surface of a transparent glass bulb in which a discharge medium mainly containing a rare gas is enclosed. An external electrode type discharge lamp having a pair of electrodes, first and second synchronizing signals having rectangular waves with different intervals, a voltage conversion circuit for converting a DC voltage of the DC power source into a high voltage, and the first A control circuit for controlling a conversion voltage of the voltage conversion circuit based on the first and second synchronization signals, and a voltage generated by the voltage conversion circuit based on the switching signal generated from the control circuit. And drive voltage generating means for generating a drive voltage for making the light quantity of the discharge lamp constant irrespective of the second synchronization signal.

  According to the present invention, even when synchronization signals having different periods are input, it is possible to realize stabilization of the lamp light amount by suppressing a change in the lamp light amount.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a circuit configuration diagram for explaining an embodiment of a discharge lamp lighting device according to the present invention. FIG. 2 is a sectional view showing a cutout part of an outer surface electrode type discharge lamp which is a dielectric barrier discharge lamp, and FIG. 3 is a longitudinal sectional view thereof. FIG. 4 is a development view of main components, and FIG. 5 is an equivalent circuit diagram of an outer electrode type discharge lamp.

Before describing FIG. 1, the structure of an outer surface electrode type dielectric barrier discharge lamp will be described first with reference to FIGS.
The discharge lamp 100 has a pair of electrodes 121 and 122 for causing discharge on the outer surface of the light-transmitting bulb 11. At least one of the electrodes 121 and 122 may be provided on the inner surface of the bulb 11.

  As shown in the sectional view of FIG. 3, the bulb 11 includes a phosphor layer 13, a pair of electrodes 121 and 122, an aperture 14, a translucent resin sheet 15, and a translucent insulating tube 16.

  The bulb 11 is elongated, for example, quartz glass having a diameter of 10 mm and an effective length of 370 mm, for example, hermetically sealed at both ends, and has an exhaust tip-off portion 111 at one end. For example, xenon is enclosed in the bulb 11 as a discharge medium. The phosphor layer 13 is formed on the inner surface of the bulb 11 at a portion other than the slit-shaped portion along the longitudinal direction.

  The electrodes 121 and 122 are each made of, for example, aluminum foil, and are attached to the outer surface of the bulb 11 so as to be spaced apart from each other in parallel as shown in FIG. The electrodes 121 and 122 are previously adhered to one surface of a translucent resin sheet 15 described later, and the translucent resin sheet 15 is wound around the outer periphery of the valve 11 to be disposed at a predetermined position on the outer surface of the valve 11. ing.

  As shown in FIG. 4 in which the translucent resin sheet 15 is developed, the electrodes 121 and 122 are formed with wave-shaped electrode main portions 41 and 42 on the translucent resin sheet 15, and the electrode main portions 41 and 42. Terminal connecting portions 43 and 44 are integrally formed at one end in the same direction. The electrode main portions 41 and 42 are configured to extend over most of the longitudinal direction of the bulb 11. Terminals 45 and 46 are electrically connected to the terminal connection portions 43 and 44, respectively, using a conductive adhesive, for example. The terminal connection portions 43 and 44 are formed in a rectangular shape so that the contact area with the terminals 45 and 46 is increased. Moreover, the terminals 45 and 46 protrude outside from the translucent resin sheet 15 and the translucent insulating tube 16 which is a translucent heat shrinkable tube.

  The aperture 14 is a slit-like portion in which the phosphor layer 13 is not formed along the longitudinal direction of the bulb 11. Therefore, the portion of the aperture 14 of the valve 11 can be seen through the valve 11 through the valve 11.

  The translucent resin sheet 15 is made of, for example, transparent PET (Polyethylene Terephthalate), has a length that covers the substantial length of the bulb 11, and has a width that covers the aperture 14 with respect to the circumferential direction of the bulb 11. Have. As described above, the pair of electrodes 121 and 122 are attached to one surface at a predetermined interval. Furthermore, an acrylic adhesive material is applied thereon and adhered to the outer surface of the bulb 11. As a result, the electrodes 121 and 122 are disposed at positions on both sides of the aperture 14, and the translucent resin sheet 15 is stuck on the aperture 14.

  The translucent insulating tube 16 is made of a transparent fluororesin and covers the entire circumference of the bulb 11 from above the electrodes 121 and 122 and the aperture 14.

  As shown in FIG. 5, the equivalent circuit of the discharge lamp 100 is constituted by a series circuit including a capacitor Cin1, a load resistor RL and a capacitor Cin2, and a parallel circuit of capacitors Cout1 and Cout2. Capacitors Cin1 and Cin2 are capacitances formed between the electrodes 121 and 122 and the inner surface of the bulb 11. Therefore, the capacitances of the capacitors Cin1 and Cin2 are determined by the areas of the electrodes 121 and 122, the relative dielectric constant and the thickness of the glass that is the constituent material of the bulb 11. Thus, the discharge lamp 100 has at least a capacity.

  Here, the discharge lamp lighting device of the present invention will be described with reference to FIG.

  In FIG. 1, reference numeral 21 denotes a DC power supply of 24V, for example. Connected to one end of the choke coil L to be constructed.

  The voltage conversion circuit 23 connects the other end of the choke coil L to the anode of the diode D1 and to the drain of the switching MOS FET Q1 whose source is grounded. The gate of the transistor Q1 is connected to the control circuit 22 via the resistor R1, and is connected to the source of the transistor Q1 via the resistor R2. The cathode of the diode D1 is grounded via the capacitor C2.

  A connection point between the diode D1 and the capacitor C2 which is the output terminal of the voltage conversion circuit 23 is connected to one end of the resistor R3 of the feedback voltage control circuit 24, and an inverter circuit 25 which is a means for generating a driving voltage of the discharge lamp 100 is provided. It connects with the connection point of primary side coil L1, L2 of the transformer TR to comprise.

  The feedback voltage control circuit 24 is connected to the other end of the resistor R3 by connecting the resistor R4 in series. The connection point of the resistors R3 and R4 is grounded via the capacitor C3, and is connected to the collector of the NPN transistor Q2 whose emitter is grounded via the resistor R5. The transistor Q2 has a resistor connected between the base and the emitter, and is connected to a control terminal CR to which a synchronizing signal supplied also from the base to the control circuit 22 is supplied via the resistor. A connection point between the resistors R3 and R4 is connected to the control circuit 22. The synchronization signal is for switching the discharge lamp 100 to monochrome / color correspondence.

  The control circuit 22 outputs a drive signal for switching control of the MOS type FET transistors Q3 and Q4, and supplies this drive signal to the gates of the transistors Q3 and Q4. The sources of the transistors Q3 and Q4 are grounded, the drain of the transistor Q3 is connected to the other end of the coil L1 whose one end is connected to the output end of the voltage conversion circuit 23, and the drain of the transistor Q4 is connected to the other end of the voltage conversion circuit 23. Connected to the other end of the coil L2 connected to the output end. Both ends of the secondary coil L3 of the transformer TR whose one end is grounded are connected to the electrodes 121 and 122 of the discharge lamp 100 described in FIG. The coil L3 has a larger number of windings than the primary side coils L1 and L2, and is set to induce a high voltage.

  Next, the operation of the lighting device of FIG. 1 will be described with reference to the timing charts of FIGS.

  When the drive signal a shown in FIG. 6A output from the control circuit 22 is supplied to the gate of the transistor Q1, the transistor Q1 is turned on / off. Energy is stored in the choke coil L when the transistor Q1 is turned on, and at the moment when the transistor Q1 is turned off, the stored energy is transferred to the load side, and the voltage output is boosted by, for example, about five times as shown in FIG. b is obtained. The transferred energy is rectified by the diode D1 and the capacitor C2, and a DC output voltage Vd shown in FIG. The output voltage Vd varies depending on the duty of the voltage output b in FIG. That is, the output voltage Vd is large when the pulse width of the voltage output b is narrow, and the output voltage Vd is small when the pulse width is wide. FIG. 6C shows the current waveform of FIG.

  When the color synchronization signal e shown in FIG. 7E having a voltage of about 10 V and a frequency of about 1 KHz is supplied to the control terminal CR of the control circuit 22 to the base of the control circuit 22 and the transistor Q2, the transistor Q2 is When the synchronizing signal e to be turned on is at the Hi level, the resistance R4 and R5 that are in parallel connection with the resistor R3 connected in series are divided by the voltage dividing ratio with the resistors R3 and R4. The output voltage of f) is obtained. This voltage is smoothed by the capacitor C3 to obtain the DC voltage v1 shown in FIG. 7G and supplied to the connection point of the primary side coils L1 and L2 of the same number of turns of the transformer TR.

  The duty of the drive signal a for turning on / off the transistor Q1, that is, the duty of the voltage output b is determined by the control circuit 22 based on the frequency of the synchronization signal e. The synchronization signal e is supplied to the control circuit 22, and based on this information, the transistor Q2 is turned on / off, and the DC voltage v1 is fed back to the control circuit 22, thereby setting the duty of the drive signal a and the DC voltage Vd. The value of is determined.

  In addition, the control circuit 22 supplies the inverted drive signals h1 and h2 shown in FIGS. 7 (h1) and (h2) to the gates of the transistors Q3 and Q4, and alternately switches the transistors Q3 and Q4 to thereby switch the transistors TR3 and Q4. Based on the voltage Vd at the connection point of the primary side coils L1 and L2, the secondary side coil L3 generates a rectangular wave high voltage Va shown in FIG.

  By the way, the drive signals h1 and h2 are reset at the timing when the synchronization signal e becomes the Hi level, and become signals for alternately turning on and off the transistors Q3 and Q4 again after the time t has elapsed due to the delay of the circuit operation of the control circuit 22. (FIG. 7 (h2)). This is due to a delay in the circuit configuration of the control circuit 22.

  Next, consider a case where the monochrome synchronization signal e 'shown in FIG. 8 (e') is supplied to the control circuit 22 and the base of the transistor Q2.

  The synchronization signal e 'is set to a frequency that is, for example, three times that of the color synchronization signal e. During the period when the synchronization signal e ′ in which the transistor Q2 is turned on is in the Hi level, the voltage is divided between the resistors R4 and R5 in the parallel connection state and the resistance R3 in the series connection, and the resistance R3 and R4 are divided in the period during the Lo level. The output voltage of FIG. 7 (f ′) is obtained by the pressure ratio. This voltage is smoothed by the capacitor C3 to obtain the DC voltage v2 shown in FIG. 7 (g ') and supplied to the connection point of the primary side coils L1 and L2 of the same number of turns of the transformer TR.

  The DC voltage v2 is lower than v1, and the control circuit 22 supplied with the DC voltage v2 increases the on-duty of the drive signal a and increases the value of the DC voltage Vd.

  When the synchronization signal e is supplied, the value of the direct-current voltage Vd serving as the power source of the inverter circuit 15 is lower than when the synchronization signal e ′ is supplied, and the voltage Va for driving the discharge lamp 100 is lower.

  Conversely, when the synchronization signal e 'is supplied, the DC voltage Vd increases, but the drive voltage Vb increases. The drive voltage Va is low, but in the oscillation suspension period due to the synchronization signal, the lamp current is not lost (broken line) as shown in FIG. 7J, and the drive voltage Vb is high, but the oscillation suspension period due to the synchronization signal is not. In many cases, as shown in FIG. 7 (j ′), there are many lamp current omissions (broken lines). By this control, the light quantity of the discharge lamp 100 can be made constant.

  Thus, by changing the feedback signal fed back from the feedback voltage control circuit 24 to the control circuit 22 based on the synchronization signal, the output voltage of the voltage conversion circuit 23 is changed, and the discharge lamp 100 of the discharge lamp 100 due to the difference in the synchronization signal is changed. The amount of light can be made almost constant.

  In this embodiment, the light quantity of the discharge lamp can be stabilized substantially constant by setting the voltage for driving the discharge lamp to the same value for both color and monochrome.

  FIG. 9 is a circuit configuration diagram for explaining another embodiment of the present invention. In this embodiment, even when a synchronization signal corresponding to monaural / color having a different period is input based on software, the lamp light amount of the discharge lamp suitable for monaural / color is stably lit. In this embodiment, the feedback voltage control circuit 24 is deleted and the control circuit 22 is a microcomputer. The description will be made assuming that the frequency relationship between the synchronization signals e and e ′ is the same as that in the above embodiment.

  The operation of FIG. 9 will be described below with reference to the operation flowcharts shown in FIGS.

  First, the control circuit 22 determines whether the frequency supplied to the control terminal CR is the synchronization signal shown in FIG. 7 (e) or the synchronization signal shown in FIG. 8 (e '). When the synchronization signal e is determined, the drive signal a in FIG. 6A corresponding to the synchronization signal e is supplied to the gate of the transistor Q1, and the transistor Q1 is on / off controlled. A DC voltage Vd based on the duty of the synchronization signal e is supplied to the primary side coils L1 and L2 of the transformer TR of the inverter circuit 25 as an output of the voltage conversion circuit 23.

  When it is determined that the signal is the synchronization signal e ', the drive signal a of FIG. 6A corresponding to the synchronization signal e' is supplied to the gate of the transistor Q1, and the transistor Q1 is turned on / off. A DC voltage Vd based on the duty of the synchronization signal e ′ is supplied to the primary side coils L <b> 1 and L <b> 2 of the transformer TR of the inverter circuit 25 as an output of the voltage conversion circuit 23.

  The DC voltage Vd supplied to the transformer TR is high in the case of the synchronization signal e when the synchronization signal is e and e ′.

  When the synchronization signal e is supplied to the control terminal CR of the control circuit 12, the drive signals shown in FIGS. 7 (h1) and (h2) are supplied to the transistors Q3 and Q4, and the synchronization signal e ′ is supplied. The drive signals shown in FIGS. 8 (h1 ′) and (h2 ′) are supplied to the transistors Q3 and Q4. When the synchronization signal e is supplied, the value of the DC voltage Vd serving as the power source of the inverter circuit 15 is lower and the drive voltage Va is lower than when the synchronization signal e ′ is supplied. On the other hand, when the synchronization signal e 'is supplied, the DC voltage Vd increases and the drive voltage Vb also increases.

  Thus, the value of the drive voltage for driving the discharge lamp 100 can be controlled in the same way when the synchronization signal e is supplied and when the synchronization signal e 'is supplied. As a result, the light quantity of the discharge lamp 100 can be made substantially constant regardless of the synchronization signal e or the synchronization signal e ′.

  In this embodiment, even when different synchronization signals for color and monochrome are supplied to the control circuit, the feedback voltage control circuit is omitted by controlling the drive voltage for driving the discharge lamp based on the software processing of the control circuit. It is possible to stabilize the light quantity of the discharge lamp almost constant with a simple configuration.

The circuit block diagram for demonstrating one Embodiment of the discharge lamp lighting device of this invention. FIG. 3 is a cross-sectional view showing a partially cutout outer electrode type discharge lamp. The longitudinal cross-sectional view of FIG. FIG. 3 is a development view of main components in FIG. 2. The equivalent circuit diagram of an outer surface electrode type discharge lamp. FIG. 2 is an operation waveform diagram for explaining the operation of FIG. 1. FIG. 2 is an operation waveform diagram for explaining the operation of FIG. 1. FIG. 2 is an operation waveform diagram for explaining the operation of FIG. 1. The circuit block diagram for demonstrating other embodiment of the discharge lamp lighting device of this invention. The flowchart for demonstrating the operation | movement of FIG.

Explanation of symbols

100 discharge lamp 21 power supply 22 control circuit 23 voltage conversion circuit 24 feedback voltage control circuit 25 inverter circuit Q1, Q3, Q4 FET transistor Q2 transistor CR control terminal L choke coil R1-R5 resistance TR transformer C1, C3 electrolytic capacitor C2 capacitor

Claims (2)

A transparent glass bulb in which a discharge medium mainly composed of a rare gas is enclosed, and an external electrode type discharge lamp having a pair of electrodes disposed on the inner surface or outer surface of the bulb;
First and second synchronization signals having differently spaced rectangular waves;
A voltage conversion circuit for converting a DC voltage of the DC power source into a high voltage;
A control circuit for controlling a conversion voltage of the voltage conversion circuit based on the first and second synchronization signals;
Based on the switching signal generated from the control circuit, the voltage generated by the voltage conversion circuit is a driving voltage that generates a driving voltage that makes the light quantity of the discharge lamp constant regardless of the first and second synchronization signals. A discharge lamp lighting device comprising: a generating unit. A discharge lamp for lighting a discharge lamp of an outer surface electrode type comprising a transparent glass bulb in which a discharge medium mainly composed of a rare gas is enclosed, and a pair of electrodes disposed on the inner surface or the outer surface of the bulb. In the lighting device,
Control means for supplying first and second synchronization signals having rectangular waves of different intervals to convert a DC voltage of a DC power source into a high voltage corresponding to the first and second synchronization signals;
Drive voltage generation means for generating a drive voltage for making the light quantity of the discharge lamp constant regardless of the first and second synchronization signals based on the switching signal generated from the control means. A discharge lamp lighting device characterized by.

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