JP2003217886A - Discharge lamp lighting device and image reader built-in device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device and an image reader built-in device using the same, capable of surely improving the balance of white color in the light received by an image reading means by adjusting the number of voltage waves generated during one-reading period and having the repeated waveform, to a specific value. <P>SOLUTION: This discharge lamp lighting device comprising a triangular wave generating circuit including a capacitor C2 and a resistance value variable resistor R3 wherein the transmitted frequency is adjusted to generate the predetermined number of triangular waves in one period of a synchronous signal mentioned below, by the operation, a control part CC1 comprising a drive signal generating circuit generating a drive signal PWM controlled on the basis of the triangular waves, a synchronous signal receiving part SYC1 for temporarily stopping the operation of the control part every receiving the synchronous signal, a lighting circuit part OC1 wherein a switching element Q1 driven by the drive signal, and an output transformer T are connected in series to a DC power source DC1, and outputting the output voltage of repeated waveform, and a discharge lamp DDL forming a phosphor layer mainly composed of three-band phosphor as its main component. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for lighting a discharge lamp containing a discharge medium mainly containing a rare gas, and an image reading device built-in apparatus using the discharge lamp lighting device.

[0002]

2. Description of the Related Art When reading a document in a color scanner or the like, a rare gas discharge type fluorescent lamp using a three-wavelength light emitting phosphor is used so that the document can be illuminated with white light without color unevenness. . This three-wavelength type phosphor is formed by mixing a red light emitting phosphor, a green light emitting phosphor and a blue light emitting phosphor. Further, a rare gas discharge type fluorescent lamp is generally turned on by applying a voltage having a repetitive waveform such as a high frequency pulse voltage between electrodes.

However, there is a difference in afterglow time between the phosphors of each color. That is, the red light emitting phosphor and the green light emitting phosphor have a long afterglow time, so that the change in the amount of light emission that occurs during one cycle of the applied voltage of the repetitive waveform is relatively small. On the other hand, the blue light emitting phosphor has a short afterglow time, and therefore the change in the amount of light emission occurring during the one cycle is large. Therefore, the integrated light amount of blue light emission during the reading cycle of the reading CCD sensor greatly changes depending on the number of voltage waves having a repetitive waveform applied during the cycle. On the other hand, the integrated light amounts of the red light emission and the green light emission during the above period have relatively little change. As a result, when the number of voltage waves of a repetitive waveform applied during the reading cycle of the reading CCD sensor changes, the white balance of the light received by the reading CCD sensor is lost and the color reproducibility is deteriorated. There is.

In order to solve the above-mentioned problem, Japanese Patent Laid-Open No. 312596/1999 receives a light receiving period signal of a reading CCD sensor, lights a fluorescent lamp in a driving period synchronized with the reading period, and A discharge lamp lighting device is described in which the rising time of a voltage having a repetitive waveform is determined based on the drive signal. (Prior art)

However, in the prior art, even if the inverter control IC that determines the driving cycle of the lighting circuit is turned on and off in synchronization with the reading cycle, the transmission of the inverter control IC is performed. The frequency is determined regardless of the reading cycle. That is, the oscillation frequency of the inverter control IC is determined by various factors such as the circuit constants of the oscillation capacitor and resistor externally connected to the inverter control IC, and the operating conditions of the oscillation transistor. As a result, the actual oscillation frequency fluctuates due to fluctuations in the constants of circuit components despite the intention of circuit design. Then, the variation of the oscillation frequency directly affects the number of repetitive waveform voltage waves applied to the fluorescent lamp during one period of the reading CCD sensor. As a result, even in the conventional technique, the reading C
The white balance of the light received by the CD sensor cannot be made sufficiently good.

According to the present invention, a discharge lamp lighting device and a discharge lamp lighting device which surely improve the white balance of the light received by the image reading means by setting the number of voltage waves having a repetitive waveform generated during one reading cycle to a predetermined value are used. An object is to provide a device incorporating an image reading device.

[0006]

According to another aspect of the present invention, there is provided a discharge lamp lighting device having a capacitor and a variable resistance resistor, wherein the variable resistance resistor is operated during one cycle of a sync signal described below. A control unit including a triangular wave generating circuit whose oscillation frequency is adjusted so that a predetermined number of triangular waves are generated, and a drive signal generating circuit which generates a PWM-controlled drive signal based on the triangular wave generated from the triangular wave generating circuit; A synchronization signal receiving unit for temporarily stopping the operation of the control unit each time a synchronization signal is received; a DC power supply; a switching element whose switching is controlled by a drive signal generated from the control unit; and a primary winding And 2
It is equipped with an output transformer having a secondary winding, and the switching element and the primary winding of the output transformer are connected in series to a DC power supply. With the switching of the switching element, the secondary winding of the output transformer has a repetitive waveform. A lighting circuit section that outputs an output voltage; a translucent airtight container, a phosphor layer formed on the inner surface of the translucent airtight container, containing three-wavelength emission type phosphor as a main component, and enclosed in the translucent airtight container And a discharge lamp having a pair of electrodes, and a discharge lamp that is lit by applying an output voltage of a lighting circuit unit between the pair of electrodes. There is.

In the present invention and the following inventions, the definitions and technical meanings of terms are as follows unless otherwise specified.

First, the control section will be described. The control unit includes a triangular wave generation circuit and a drive signal generation circuit. The triangular wave generation circuit has a capacitor and a variable resistance resistor, and its oscillation frequency is adjusted by operating the variable resistance value resistor so that a predetermined number of triangular waves are generated during one period of a synchronization signal described later. ing. The variable resistance resistor may be either a semi-fixed resistor or a variable resistor. The drive signal generation circuit generates a PWM-controlled drive signal based on the triangular wave generated by the triangular wave generation circuit. The PWM control can be used when the output is made constant or a protection operation is performed at the time of abnormality as described later. In order to perform PWM control of the drive signal, the peak value-phase angle conversion may be performed by utilizing the property that the instantaneous value of the triangular wave changes in proportion to the phase.
Then, the generated drive signal drives the switching element of the lighting circuit section to cause switching.

Further, the control section can be configured by a switching regulator IC as a main part of the triangular wave generating circuit and the drive signal generating circuit except for the required components such as the capacitor and the variable resistance resistor. In this case, the capacitor and the variable resistance resistor are externally connected to a predetermined terminal of the regulator IC.

Further, if necessary, the control unit can have a feedback control function in order to make the output of the lighting circuit unit constant. In this case, the output detection means of the lighting circuit section is provided, and when the output detection signal is at the first level, it is determined that the time is normal, and feedback control is performed during normal time. In the feedback control, the voltage, current or power of the output of the lighting circuit unit that is supplied to the discharge lamp and energizes the discharge lamp is fed back, and the voltage of the switching circuit of the lighting circuit unit is PWM-controlled by PWM control. The current or power is controlled to be constant.

Furthermore, the control unit can have an abnormal condition control function for the switching means of the lighting circuit unit in order to perform the protection operation in the abnormal condition as described above.
For example, in the control unit, the output detection signal of the lighting circuit unit is the second
When it changes to the level of, it is determined that it is an abnormal time and the protection operation control is performed. In addition, "first
"Level" means a level other than the second level described later. In addition, "protection operation control" means to stop the generation of high frequency, to generate high frequency intermittently, or to generate high frequency with low voltage, so as to protect from danger due to abnormal condition. Means to control.
Furthermore, "at the time of abnormality" means a no-load state in which the discharge lamp is not normally connected to the lighting circuit section even though the lighting circuit section is operating, or an overcurrent state in which an overcurrent flows due to, for example, a short circuit. And so on. When the control unit is made to perform the protection operation at the time of an abnormality, if the switching regulator IC having the shutdown function is used to configure the main part of the control unit and the shutdown function is activated at the time of the abnormality, the circuit configuration will be improved. Will be easier.

Furthermore, the control unit can be configured to stop the protection operation for a predetermined time when the discharge lamp is started. As a result, this type of discharge lamp requires a very high voltage to be applied at the time of starting, and an abnormal discharge that is not the main discharge through the discharge medium is likely to occur for a short time, so avoiding such a transient state at the time of starting. The reliable protection operation can be performed.

Next, the synchronizing signal receiving section will be described.
The synchronization signal receiving section acts so as to temporarily stop the operation of the control means each time the synchronization signal is received from the outside such as the image reading means. When the inverter IC is used for the control unit as in the above-mentioned conventional technique, the ON / O
A synchronization signal receiver can be connected to the FF terminal. In this case, it is necessary to invert the sync signal using an inverting circuit. On the other hand, as will be described later, the synchronization signal receiving section can be connected so as to temporarily short-circuit the resistor or the capacitor of the time constant circuit of the triangular wave generating circuit. In this case, it is not necessary to use the inverting circuit.

Next, the DC power source will be described. The DC power supply supplies DC power to the lighting circuit section described later. However, in addition to this, the DC power supply can also supply power to the control unit and other circuit elements. The DC power supply may be either a rectified DC power supply or a battery power supply. The former is preferably smoothed, but may be a non-smoothed DC power supply.

Next, the lighting circuit section will be described. The lighting circuit unit converts the DC power supply voltage into an output voltage having a repetitive waveform and supplies the discharge lamp with a required voltage and electric energy of a required power, thereby performing a dielectric barrier discharge on the discharge lamp. It is a means to make. Therefore, the lighting circuit unit includes a switching element and an output transformer. The switching of the switching element is controlled by a drive signal generated from the control unit, and a voltage having a repetitive waveform is formed. The output transformer boosts the voltage of the repetitive waveform as needed to generate the output voltage of the repetitive waveform. In order to perform the above operation,
The switching element and the primary winding of the output transformer are connected in series to the DC power supply. As a result, the switching element switches the DC voltage to form a voltage having a repetitive waveform, preferably a high frequency.
The voltage of the repetitive waveform is boosted by the output transformer and output between the secondary windings. The term "high frequency" means a frequency of 1 KHz or higher, preferably 4 to 10
Refers to MHz.

The output voltage of the lighting circuit section may be in either pulse or AC form as long as it has a repetitive waveform. The "AC voltage" refers to a mode in which positive and negative waveforms are applied alternately and continuously without a rest period,
Besides positive / negative symmetrical alternating current, positive / negative asymmetric alternating current may be used. For example, harmonics can be superimposed on the fundamental wave of a sine wave to make the rising and falling portions of the voltage waveform relatively steep, or a DC voltage can be superimposed to form a positive / negative asymmetric waveform. The waveform is adjusted so that the high-frequency AC voltage will flow through the lamp current with a sufficient rest period, so that afterglow occurs in the discharge lamp during the rest period of the lamp current, as in the case of applying pulse voltage. Can be made.

Further, the lighting circuit section is a flyback type,
A switching regulator or inverter of various circuit types such as a forward type, a half bridge type or a push-pull type can be configured. However, the present invention is not limited to this, and it may be a high frequency generating means composed of, for example, an oscillator and a power amplifier.

The switching means acts to generate a high frequency by switching, and the number thereof may be single or plural depending on the circuit system. As the switching means, a semiconductor switch such as MOSFET or bipolar transistor can be used.

The output transformer acts so as to electrically insulate the primary winding and the secondary winding from each other, and if at least the primary winding and the secondary winding are provided, the tertiary winding and a plurality of windings are provided. It is allowed to have a primary winding or a secondary winding of Further, the discharge lamp performs dielectric barrier discharge by applying an output voltage induced to the secondary winding of the output transformer.

Next, the discharge lamp will be described. The discharge lamp includes at least a translucent airtight container, a phosphor layer, a discharge medium, and a pair of electrodes.

The light-transmissive airtight container may be any material as long as it is a dielectric having airtightness and heat resistance against operating temperature, but is usually soft glass, hard glass or Semi-hard glass is used. When using visible light for illumination, the discharge container needs to transmit only visible light to be used. The shape of the translucent airtight container is
Not limited. Therefore, the translucent airtight container is allowed to have a desired shape depending on the purpose of its illumination. For example, it can be tubular, flat, or the like. It may be tubular, straight pipe, or curved pipe. In addition, the curved tube is circular, semicircular, U-shaped, W-shaped,
It can be saddle-shaped or spiral-shaped. Further, even when the discharge lamp has a tubular shape, the thickness and length of the tube are arbitrary, and a size suitable for the application may be selected.

The phosphor layer is formed on the inner surface side of the translucent airtight container. And, it is composed mainly of a three-wavelength light emitting phosphor. As described above, this three-wavelength light emitting phosphor is used by combining the red light emitting phosphor, the green light emitting phosphor and the blue light emitting phosphor at a predetermined ratio. The red light emitting phosphor and the green light emitting phosphor have a relatively long afterglow time, whereas the blue light emitting phosphor has a relatively short afterglow time. The term "inner surface of the discharge vessel" means that not only the phosphor layer is directly formed on the inner surface of the discharge vessel, but also a protective film is first formed on the inner surface of the discharge vessel, and the phosphor layer is formed thereon. This means that the phosphor layer can be indirectly formed. The three-wavelength light-emitting phosphor can be mixed to form a single phosphor layer, or can be formed into a plurality of phosphor layers for each color-emitting phosphor.

The discharge medium is mainly composed of a rare gas. As the rare gas, xenon is preferable, but if necessary, any one kind of krypton, argon, neon and helium or any plural kinds thereof can be mixed and used. The phrase "mainly composed of a rare gas" means that halogen or the like is allowed to be contained in addition to the rare gas, and the main body of discharge may be a rare gas.

The pair of electrodes are arranged inside the transparent airtight container so that discharge of the discharge medium occurs. In addition, the pair of electrodes may be arranged on either the inside or the outside of the translucent airtight container. Hereinafter, for convenience, the electrode provided on the outer surface of the transparent airtight container will be referred to as “external electrode”, and the electrode provided inside the transparent airtight container will be referred to as “internal electrode”. As a mode of the paired electrodes, both of the paired electrodes may be external electrodes, one may be an external electrode and the other may be an internal electrode, and both of the paired electrodes may be internal electrodes. . If at least one of the paired electrodes is an external electrode, a capacitance having a wall of the light-transmitting hermetic container as a dielectric is interposed between the electrodes, so that a dielectric barrier discharge can be generated. Further, in the case where the pair of electrodes are both internal electrodes, the discharge is directly generated regardless of the wall of the translucent airtight container.

The external electrode is disposed so as to substantially contact the outer surface of the discharge vessel. Then, it is preferably made of a conductive film. The conductive film is a conductive metal foil such as aluminum, silver or copper, a conductive metal vapor deposition film adhered to a translucent resin sheet described later, a plating film or a conductive metal foil, and a screen printing conductive paste. Formed coating film, ITO film, NES
A film or the like can be used. When the external electrode is made of a conductive thin film, the external electrode may be formed in a ribbon shape or may be formed in a deformed shape such as a meandering shape.

However, the external electrode is not limited to the conductive film, and is made of a conductive material such as a coil or a mesh structure, if necessary, and is disposed so as to be substantially in contact with the outer surface of the discharge vessel. It can be in the form. In addition, the external electrode is "almost disposed in contact with the outer surface of the discharge vessel", it is desirable that the entire external electrode is in contact with the outer surface of the surface of the discharge vessel, but this is not an essential requirement. In general, it means that the external electrode should be in contact with the outer surface of the discharge vessel. Furthermore, the external electrode may have a size such that at least a part thereof extends in the longitudinal direction, that is, the axial direction of the discharge vessel. And, in the outer peripheral direction of the discharge vessel, it can be arranged within the angular range forming the entire circumference or a part of the outer circumference. Furthermore, when the external electrode is composed of a coil, a mesh structure and a transparent conductive film, these structures transmit the external electrode or pass through the gap between the external electrodes to guide the light to the outside. Therefore, it can be arranged around the entire circumference of the discharge vessel.
On the other hand, when the external electrode is made of a metal foil, and when the external electrode is made of a metal foil, the metal foil is previously attached to one surface of a translucent resin sheet described below and applied to the transparent resin sheet. It can be arranged by adhering it to the outer surface of the discharge vessel with the adhesive. However, it is also possible to attach the metal foil directly to the outer surface of the discharge vessel. Furthermore, the width of the external electrode may change in the axial direction of the discharge vessel.

Next, in order to bring the external electrode into contact with the outer surface of the discharge vessel, an adhesive may be applied to the contact surface of the external electrode in advance, and the external electrode may be attached to the discharge vessel with the adhesive. However, an adhesive may be applied to a portion of the discharge container where the external electrode is to be contacted, and the external electrode may be attached thereon. Further, without using a pressure sensitive adhesive or an adhesive, the external electrode may simply be brought into contact with the planned contact portion, and the translucent resin sheet to which the pressure sensitive adhesive is applied may be wound on the outer electrode over the entire circumference of the discharge vessel.

Further, the arrangement of the pair of electrodes will be described. That is, the electrode arrangement can be arbitrarily selected from the following various modes. 1 Inner / Outer Electrode Type Arrangement The inner / outer electrode type arrangement is an electrode arrangement in which one or a plurality of inner electrodes and one or a plurality of outer electrodes are combined. In addition, this arrangement is divided into a short internal electrode and a long internal electrode extending along the longitudinal direction of the discharge vessel. (1) Electrode Arrangement Using Short Internal Electrodes In this electrode arrangement, short electrodes similar to those used for a normal internal electrode type fluorescent lamp are used. (1-1) Arrange a single internal electrode at one end of the discharge vessel,
Electrode arrangement in which a single external electrode is arranged on the outer surface of the discharge vessel (1-2) A pair of internal electrodes is arranged at both ends of the discharge vessel,
Electrode arrangement in which a single external electrode is arranged on the outer surface of the discharge vessel
In the case of this electrode arrangement, both the pair of internal electrodes are connected to one pole of the lighting circuit, and the external electrodes are connected to the other pole of the lighting circuit, and a pair of lighting circuits are prepared and one pole of each lighting circuit is prepared. Is separately connected to the internal electrode, and the external electrode is connected to the other pole of the pair of lighting circuits with the same potential. (1-3) Electrode arrangement in which internal electrodes are arranged at both ends of the discharge vessel and a pair of external electrodes are arranged on the outer surface of the discharge vessel In the case of this electrode arrangement, the internal electrodes and the external electrodes face each other in a one-to-one relationship. (1-4) Arrangement of internal electrodes at both ends and middle of the discharge vessel, and arrangement of facing a single external electrode in common (1-5) Arrangement of internal electrodes at both ends and middle of the discharge vessel to perform discharge Electrode arrangement for arranging the external electrode facing the internal electrode on the outer surface of the container (2) Electrode arrangement using a long internal electrode. In this electrode arrangement, a length of the electrode extending over substantially the entire length of the discharge vessel in the longitudinal direction is used. Internal electrodes are used. Both ends of the internal electrode are airtightly penetrated both ends of the discharge vessel and led out to the outside, and only one end of the internal electrode is airtightly passed through one end of the discharge vessel and led out to the outside. Is located inside the other end of the discharge vessel. 2 External electrode type arrangement In this arrangement, a pair of external electrodes are arranged on the outer surface of the discharge vessel so as to face each other. One or more pairs of external electrodes can be arranged along the longitudinal direction of the discharge vessel. In the case of the aperture type, the external electrodes must be arranged so as not to substantially block the light projection from the aperture. The pair of electrodes may be inside or outside the discharge vessel as long as at least one of them is arranged inside the discharge vessel so as to generate a discharge through the discharge medium. 3 Internal electrode type arrangement In this arrangement, a pair of short internal electrodes are generally sealed inside both ends of a light-transmitting hermetic container.

Other Configurations Although not essential to the present invention, the performance of the discharge lamp lighting device may be improved or functions may be added by adding the following configuration. 1 Output Detection Means The output detection means is used when the control section performs negative feedback control in order to obtain a stable repetitive waveform output from the lighting circuit section. Then, the output of the repetitive waveform of the lighting circuit unit is negatively fed back to control the switching of the switching element of the lighting circuit unit. The output detection signal is selected from the following signal formats according to the negative feedback control format. That is, when constant voltage control is performed, the output voltage having a repetitive waveform is detected. The constant current control detects a load current, and the constant power control detects a load power or a current or power proportional thereto. Both the output voltage and the load current can be detected on the primary or secondary side of the output transformer. However, since a boosting transformer is generally used for these detections, it is preferable to detect them on the primary side in consideration of insulation.

When the output voltage and the load current are detected for constant power control, they may be detected separately, or the voltage and the current may be pseudo-detected by a single detection circuit. Good. It should be noted that the specific configuration of the detection circuit is not particularly limited because various known means can be appropriately adopted. 2 Overcurrent Detection Means When an overcurrent flows in the load circuit, the overcurrent detection means detects the overcurrent and stops the drive signal generation or narrows the output to a safe level. In the former case, the shutdown function of the switching regulator IC of the control unit can be activated. Also,
In the latter case, the output can be reduced by PWM control. 3 No-load detection means No-load detection means detects a no-load state on the secondary side of the output transformer and forcibly changes the output operation detection signal control-input to the control unit to the second level. Is. Whether the secondary side of the output transformer is loaded or unloaded when the lighting circuit section is operating depends on the voltage, current or load of the secondary side of the output transformer of the discharge lamp. It can be detected by an operating state such as temperature or light, but it may be detected by the deviation thereof.

To forcibly change the output detection signal controlled and input to the control unit to the second level when the no-load state is detected, for example, a switch is provided and a part of the output detection signal or All can be short-circuited or open to reduce the level. Alternatively, conversely, the output detection signal may be amplified to increase its level. Therefore, the “second level” may be a level that is electrically different from the level of the output detection signal that is normally present and that is clearly different from the level of the output detection signal.

Finally, the operation of the present invention will be described.
In the present invention, since the variable resistance type resistor is used for part or all of the resistors that determine the time constant of the triangular wave in the triangular wave generation circuit of the control unit, it is necessary to operate this variable resistance type resistor. Thus, the oscillation frequency of the triangular wave can be adjusted so that a predetermined number of triangular waves are generated in one cycle of the synchronization signal. To adjust the oscillation frequency,
For example, by monitoring the triangular wave appearing at both ends of the capacitor of the triangular wave generating circuit using a frequency counter and operating the variable resistance resistor so that the repeating frequency of the triangular wave becomes a predetermined value, it can be easily realized. it can. In this case, in order to monitor the triangular wave without affecting the operation of the triangular wave generating circuit, it is preferable to interpose an impedance conversion circuit between the capacitor of the triangular wave generating circuit and the frequency counter.

In this way, the control section generates a PWM-controlled drive signal based on the triangular wave. The drive signal switches the switching element of the lighting circuit unit. As a result, the lighting circuit section outputs an output voltage having a repetitive waveform and applies it between the paired electrodes of the discharge lamp. As a result of the output voltage having a repetitive waveform being applied between the paired electrodes, the discharge lamp is lit by the discharge, and visible light is emitted from the phosphor layer. Each time the output voltage is applied, it is generated in pulse form. However, since the number of voltage waves having a repetitive waveform applied to the discharge lamp during one reading cycle becomes a predetermined number, the integrated light amount of blue emission of the discharge lamp received by the image reading means becomes substantially constant.

According to a second aspect of the present invention, there is provided an image reading apparatus built-in apparatus main body having an image reading apparatus for reading an original image at a predetermined cycle and having an image reading means for generating a synchronizing signal; The discharge lamp according to claim 1, wherein the discharge lamp is arranged in the main body of the image reading device built-in device so as to illuminate the original image so that the sync signal receiving section receives the sync signal generated by the image reading means of the main body of the image reading device built-in device. And a lighting device.

In the present invention, the "image reading device" means
This is an apparatus for reading an original image illuminated by a discharge lamp with an image reading means and performing an image forming process to form image data. In addition, “image reading device built-in equipment” means
This is a concept including all devices incorporating the image reading device, and corresponds to, for example, a copying machine, a facsimile, a scanner, or the like. The "image reading device built-in device main body" refers to the remaining part of all the elements constituting the image reading device built-in device except the discharge lamp lighting device. further,
The "image reading unit" is a reading unit that reads an original image line by line during a synchronization signal, such as a CCD line sensor.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show a first embodiment of a discharge lamp lighting device of the present invention. FIG. 1 is a circuit diagram, FIG. 2 is a cross sectional view of the discharge lamp, and FIG. 3 is an external electrode of the discharge lamp. FIG. 4 is a development view of the translucent resin sheet, FIG. 4 is a circuit block diagram for explaining a triangular wave oscillation frequency adjusting method, and FIG. 5 is a waveform diagram for explaining a relationship between the synchronizing signal and the triangular wave.

In FIG. 1, DC1 and DC2 are a pair of DC power supplies, CC1 and CC2 are a pair of control units, and SYC1 and S.
YC2 is a pair of synchronization signal receiving units, OC1 and OC2 are a pair of lighting circuit units, OPD1 and OPD2 are a pair of output detection means, OCD1 and OCD2 are a pair of overcurrent detection means, and DD.
L is a discharge lamp. Hereinafter, each component will be described.

Each of the pair of DC power supplies DC1 and DC2 rectifies and smoothes commercial AC, and the negative electrode is grounded. In FIG. 2, C11 and C12 are smoothing capacitors. Although not shown, a start switch is inserted between the DC power supplies DC1 and DC2 and a load-side circuit connected to the DC power supplies DC1 and DC2, and receives a start signal coming from the outside to turn on the start switch.

The pair of control units CC1 and CC2 are respectively for switching regulator I having a shutdown function.
C and a capacitor C2 and resistors R1, R2 and R3 external to the triangular wave generating circuit. In the regulator IC, terminals 8 and 7 are connected to both poles of DC power supplies DC1 and DC2, and a capacitor C2 and a resistor R1 are provided inside.
The remaining part of the triangular wave generating circuit excluding R2 and R3 and the drive signal generating circuit are provided. The above I
The terminal 7 of C is grounded. The resistor R1 is connected between the terminal 6 of the regulator IC and the ground. The resistor R3 is a variable resistance value resistor including a semi-fixed capacitor, and is connected in series with the resistor R2 to form a regulator I
It is connected between terminal 5 of C and ground. Capacitor C
2 is connected between the terminal 4 of the regulator IC and the ground. Then, the resistors R1, R2, R3 and the capacitor C2 form a time constant circuit of the triangular wave generating circuit, and when the resistor R3 is operated, the oscillation frequency of the triangular wave generating circuit changes. Since the oscillation frequency is adjusted in advance as described later, the triangular wave generation circuit operates so as to generate a predetermined number of triangular waves in one cycle of the synchronization signal described later.

A pair of synchronization signal receivers SYC1 and SYC2
Are each mainly configured by a transistor switch Q2, and have a synchronization signal receiving terminal t1. The transistor switch Q2 includes control units CC1 and C.
It is connected in parallel to the resistor R1 of C2, and the synchronization signal receiving terminal t
When the synchronization signal arrives at 1, the resistor R1 is temporarily short-circuited to temporarily stop the operation of the triangular wave generation circuit.

The pair of lighting circuit units OC1 and OC2 respectively include a switching element Q1 and an output transformer T, and the switching element Q1 and the primary winding pw of the output transformer T are connected in series so that both poles of the DC power supplies DC1 and DC2 are connected. Connected in between. The switching element Q1 is a MOSFET
Control unit CC1, C between its gate and source.
It turns on when the drive signal output from the terminal 1 of C2 is applied. Then, the secondary winding s of the output transformer T
An output voltage composed of the high frequency pulse voltage boosted to w is obtained.

A pair of output detection means OPD1, OPD2
Is composed of a voltage divider VD1, resistors R4 and R5, a diode D1 and capacitors C3 and C4,
The outputs of the pair of lighting circuit units OC1 and OC2 are detected. The voltage divider VD1 is connected between the connection point of the primary winding wp of the output transformer T and the switching means Q1 and the ground point. The divided voltage of the voltage divider VD1, that is, the voltage drop of the resistor R7 is applied to the parallel circuit of the resistor R5 and the capacitor C3 via the resistor R4 and the diode D1 in series. The capacitor C4 is connected in parallel with a part of the resistor R6 of the voltage divider VD. Then, the high frequency voltage appearing in the primary winding wp of the output transformer T is taken out as a divided voltage of the voltage divider DV1, rectified by the diode D1, integrated by the resistor R5 and the capacitor C3, and the control unit. C
C1 and CC2 regulator ICs have their terminals 3 and 7
A negative feedback control is performed by PWM control of the drive signal. Since the capacitor C4 is connected as described above, the voltage drop across the resistor R7 of the voltage divider VD1 is approximately proportional to the output power of the lighting circuit units OC1 and OC2. Power control can be performed.

A pair of overcurrent detecting means OCD1 and OCD2
Is composed of a current detecting element R8, resistors R9 and R10, and a beard removing capacitor C5.
1. Detect overcurrent flowing through OC2. Current detection element R
8 is composed of a resistor having a small value, the lighting circuit section OC1,
It is inserted in series between the source of each switching means Q1 of OC2 and the ground point. Resistors R9, R
Reference numeral 10 divides the voltage drop of the current detection element R8 between both ends of the resistor R10 to extract a current detection signal. The beard removing capacitor C5 absorbs and removes the beard when the current detection signal voltage obtained across the resistor R10 includes the beard. Then, the beard-removed current detection signal is control-inputted to the terminal 2 of the regulator IC of the control means CC1 and CC2.

The discharge lamp DDL is a transparent airtight container 1.
1, phosphor layer 12, two pairs of external electrodes 13A, 13A, 1
3B, 13B, aperture 14, translucent resin sheet 1
5. The transparent insulating tube 16 is provided.

The translucent airtight container 11 is made up of a glass bulb 11a which is elongated and hermetically sealed at both ends, has an exhaust tip-off portion at one end, and has xenon sealed therein as a discharge medium.

The phosphor layer 12 is formed on the inner surface of the translucent airtight container 1 except for the slit-shaped portion along the longitudinal direction.

Two pairs of external electrodes 13A, 13A, 13B,
13B each are made of aluminum foil and meander in a wavy shape as shown in FIG. 3, but as a whole, as shown in a simplified form in FIG. It is arranged by being attached to the outer surface in the longitudinal direction of the container 11. That is, one pair 13A, 13A
1 are arranged in the upper half of the transparent airtight container 11 in the longitudinal direction in FIG. 1, and the other pair 13B, 13B are arranged in the lower half as well. Then, one pair 13B, 13B of the external electrodes is connected to the secondary winding of the output transformer T of the lighting circuit section OC1. Also, the other pair 13
B and 13B are connected to the same portion of the output transformer T of the lighting circuit unit OC2. As a result, the discharge lamp DDL shares the translucent airtight container 11, but operates like two discharge lamps connected in parallel. Therefore, the amount of light increases and the uniformity of the brightness in the tube axis direction improves.

As shown in FIG. 3, each external electrode 13 is attached in advance to one surface of a transparent resin sheet 15 which will be described later, and the transparent resin sheet 15 is attached to the outer periphery of the transparent airtight container 11. By wrapping, it is arranged at a predetermined position on the outer surface of the translucent airtight container 11. In addition, each external electrode 13 includes a corrugated electrode main portion 13a, a terminal connecting portion 13b, and a terminal 13.
It consists of c. The electrode main portion 13a is configured to have a wavy shape and extend over most of the length of the translucent airtight container 11. The terminal connecting portion 13b is the electrode main portion 13
It is connected to one end of a and is formed in a rectangular shape so that the contact area with the terminal 13c is increased. Terminal 13
c is adhered to the terminal connecting portion 13b with a conductive adhesive and protrudes from the translucent resin sheet 15 and the translucent heat shrinkable tube 16 to the outside.

The aperture 14 is formed by a portion in which the phosphor layer 12 is not formed in a slit shape along the longitudinal direction of the translucent airtight container 11. Therefore, the portion of the aperture 14 of the translucent airtight container 11 looks transparent to the inside of the translucent airtight container 11 through the glass bulb 11a.

The translucent resin sheet 15 is made of transparent PET, has a length substantially over the entire length of the translucent airtight container 11, and is located above the aperture 14 in the circumferential direction of the translucent airtight container 11. It has such a width as to cover from. As described above, the pair of external electrodes 13 and 13 are attached to one surface at a predetermined interval, and an acrylic adhesive is further applied onto the external electrodes 13 to be attached to the outer surface of the translucent airtight container 11. As a result, the pair of external electrodes 13, 13 are arranged on both sides of the aperture 14 with the aperture 14 sandwiched therebetween, and the translucent resin sheet 15 is also adhered onto the aperture 14.

The translucent insulating tube 16 is made of transparent fluororesin, and has external electrodes 13A, 13A, 13B, 13B.
Also, the entire circumference of the translucent airtight container 11 is covered from above the aperture 14.

Next, the circuit operation will be described. When the synchronizing signal arrives from the image reading means, the control units CC1 and CC
Each of the triangular wave generation circuits 2 of 2 temporarily stops its operation, but then restarts its operation to generate a PWM-controlled drive signal. As will be described later, since the oscillation frequency of the triangular wave generation circuit is adjusted to a predetermined value, the frequency of the drive signal is also restricted to a predetermined value. The pair of lighting circuit units OC1 and OC2 have respective switching means Q.
1 operates as a switching regulator as a result of being switched by the drive signal, so that the boosted high-frequency pulse voltage is induced in the secondary winding ws of the output transformer T and output. Then, the output high frequency pulse voltage is applied to the two pairs of external electrodes 13A, 1A of the discharge lamp DDL.
Since it is applied between 3A, 13B, and 13B, the discharge lamp DDL is lit like two lamps. Discharge lamp DD
When L is turned on, ultraviolet rays are radiated by the dielectric barrier discharge of xenon in the translucent airtight container 11,
Since the phosphor layer 12 is irradiated, the phosphor is excited to generate visible light. Since the number of triangular waves in one cycle of the synchronization signal is the predetermined number as described above, the lighting frequency of the discharge lamp DDL is constant, and thus the difference in afterglow time between the phosphors is small. Even if there is, the white balance of the received light is favorably maintained when the image is read.

Further, as a result of the generation of the drive signal in which the triangular waves of the control units CC1 and CC2 are PWM-controlled according to the detection output obtained by the output detection means OPD1 and OPD2, the discharge lamp DDL is subjected to constant power control. Further, when the load circuit is short-circuited, overcurrent detection means OCD1 and OCD2
The switching regulator IC shuts down due to the detection output of 1 to perform a protective operation.

Next, referring to FIG. 4, control units CC1 and C1
A method of adjusting the oscillation frequency of the triangular wave generating circuit in C2 will be described. Note that FIG. 4 shows a configuration in which the oscillation frequency is adjusted for one of the pair of triangular wave generation circuits for convenience. In the figure, the same parts as those in FIG. 21 is a mounting board of the discharge lamp lighting circuit device, 22 is a start signal line, 2
3 is a synchronizing signal line, 24 is an impedance conversion circuit, 25
Is a frequency counter.

The mounting board 21 is mounted with the circuit portion of the discharge lamp lighting device shown in FIG.
N1, an output side connector CN2, a ground terminal t2, a DC constant voltage terminal t3 and a triangular wave output terminal t4 are provided. The input side connector CN1 has input terminals CN1-1 to CN-4.
Is equipped with. A DC power supply DC is connected to the input terminals CN-1 and CN-3. The activation signal line 22 is connected to the input terminal CN-2. The sync signal line 23 is connected to the input terminal CN-4. The output side connector CN2 has an output terminal C.
Equipped with N-1 and CN-9, these have a discharge lamp DDL
The external electrodes 13, 13 forming a pair are connected. Ground terminal t
2, DC constant voltage terminal t3 and triangular wave output terminal t4,
The wiring board can be constructed by lands of a corresponding potential, but if necessary, a special terminal can be arranged. The terminal voltage of the capacitor C2 in FIG. 1 appears at the triangular wave output terminal t4.

The impedance conversion circuit 24 is mainly composed of a voltage divider VD2 and an operational amplifier OP, and the voltage divider VD2 is connected between a ground terminal t2 and a DC constant voltage terminal t3. The operational amplifier OP has its inverting input terminal connected to the output of the voltage divider VD2, and its non-inverting input terminal connected to the triangular wave output terminal t4. Then, the pulse voltage output from the impedance conversion circuit 24 is obtained at the output terminal of the operational amplifier OP.

The output of the impedance conversion circuit 24 is input to the frequency counter 25.

Next, description will be made with reference to FIGS. 4 and 5. 4 and 5, waveform A is a synchronization signal, waveform B is a triangular wave, waveform C is a waveform after impedance conversion,
Are shown respectively. The waveforms B and C have different waveforms but have the same frequency.

When one cycle of the synchronizing signal is 238 μs and the time width of the synchronizing signal is 3 μs, the quiescent period is 235 μs. Therefore, the oscillation frequency of the triangular wave is adjusted so that the number of triangular waves during the quiescent period is constant, for example 16. To do. The oscillation frequency at this time is 68.2 kHz, and the resistor R3 in FIG. 1 may be adjusted so that the value of the frequency counter becomes 68.2 kHz. However, since the drive signal generated in the control unit CC based on the triangular wave is generated intermittently for each triangular wave including the peak, the time width t of about one triangular wave is generated.
Can afford. When converted into an oscillation frequency, the maximum is ± 2 kHz. Therefore, in the above case, 68.
Within the range of 2 ± 2 kHz, the number of triangular waves generated during the pause period of the synchronizing signal can be set to 16. However, in practice, it is preferable to manage within a narrower range in consideration of variations.

FIG. 6 is a longitudinal sectional view and a lateral sectional view showing a discharge lamp in a second embodiment of the discharge lamp lighting device of the present invention. In the figure, the same parts as those in FIG. In this embodiment, the pair of electrodes is composed of the outer electrode 13C and the inner electrode 13D, and the pair of electrodes is one set. Therefore, although not shown, in order to light the discharge lamp of the present embodiment, a DC power supply, a control unit, a synchronization signal receiving unit, a lighting circuit unit, and the like are respectively configured.

The external electrode 13C is formed by winding a conductive metal wire around the outer circumference of the transparent airtight container 1 in a coil shape. On the other hand, the internal electrode 13D is composed of a pair of short cold cathodes, and is sealed inside both ends of the translucent airtight container 1.
These cold cathodes are commonly connected to one pole of the lighting circuit unit. The external electrode 13C is similarly connected to the other pole. Further, in the figure, reference numerals 15 and 15 denote a pair of lead wires that are sealed by penetrating both ends of the translucent airtight container 11,
An internal electrode 13D of a cold cathode is supported inside the transparent airtight container 11.

FIG. 7 is a conceptual cross-sectional view showing a scanner as an embodiment of the image reading device incorporated equipment of the present invention. In the figure, 21 is a movable image reading mechanism, 22 is a signal processing device, 23 is an original image mounting surface, 24 is a lighting circuit section,
25 is a case.

In the present embodiment, the movable image reading mechanism 21 mainly includes a discharge lamp 21a, a mirror 21b, an integrated lens 21c, a CCD line sensor 21d and a drive mechanism (not shown). Although not shown, the discharge lamp, the self-phonic lens and the C
The CD line sensor can also be the main component.
The discharge lamp 21a has the structure shown in FIGS. Then, the light emitted from the aperture 14 is applied to the original image such as a document (not shown) through the original image mounting surface 23. The reflected light from the original image is reflected by the mirror 21.
It is arranged so that it is reflected in a predetermined direction by b, condensed by the integrated lens 21c, and received by the CCD line sensor 21d, that is, the image reading means.

The movable scanning mechanism 21 moves with respect to the original image draft placement surface 23 to scan and read the original image.

The signal processing device 22 processes the output signal of the CCD line sensor 21d by the signal processing device 22 to form an image signal.

The lighting circuit section 24 is arranged at a fixed position,
The discharge lamp 21a is turned on by applying a high frequency pulse voltage.

The case 25 accommodates the above-mentioned components inside.

Then, the movable CCD line sensor 21
d receives and scans the reflected light from the original image in the direction perpendicular to the moving direction.

[0070]

According to the first aspect of the present invention, the variable resistance type resistor having the capacitor and the variable resistance type resistor is operated to generate a predetermined number of triangular waves during one period of the synchronizing signal described later. Based on the triangular wave generated by the triangular wave generating circuit and the triangular wave generating circuit whose oscillation frequency is adjusted.
A control unit including a drive signal generation circuit for generating a drive signal subjected to WM control, a synchronization signal reception unit that temporarily stops the operation of the control unit each time a synchronization signal is received, a DC power supply, and the drive described above. Equipped with a switching element whose output is controlled by a signal and an output transformer, the primary windings of the switching element and the output transformer are connected in series to a DC power supply, and a repetitive waveform output voltage is output to the secondary winding of the output transformer A lighting circuit section that
A phosphor layer containing a three-wavelength light-emitting phosphor as a main component is formed on the inner surface side of a translucent airtight container, a discharge medium containing a rare gas as a main component is enclosed, and a pair of electrodes is provided between the electrodes. The discharge lamp that is lit by applying the output voltage of the lighting circuit section is lit, so that the number of voltage waves having a repetitive waveform generated in one reading cycle is set to a predetermined value, and the light receiving unit of the image reading unit receives light. It is possible to provide a discharge lamp lighting device that reliably improves the white balance.

According to the second aspect of the present invention, the main body of the image reading apparatus incorporating the image reading apparatus, which is equipped with the image reading means for performing the reading operation of the original image in a predetermined cycle and generating the synchronizing signal, and the main body of the image reading apparatus incorporating the apparatus. 2. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device is provided in the main body of the device incorporating the image reading device to illuminate the original image so that the synchronizing signal receiving section receives the synchronizing signal generated by the image reading means. By doing so, it is possible to provide an image reading device built-in device having the effect of the first aspect.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a discharge lamp lighting device of the present invention.

FIG. 2 is a cross-sectional view of the same discharge lamp.

FIG. 3 is a development view of the external electrodes of the discharge lamp and the translucent resin sheet.

FIG. 4 is a circuit block diagram which similarly illustrates a method of adjusting the oscillation frequency of a triangular wave.

FIG. 5 is a waveform diagram that also illustrates the relationship between the synchronization signal and the triangular wave.

FIG. 6 is a vertical sectional view and a horizontal sectional view showing a discharge lamp in a second embodiment of a discharge lamp lighting device of the present invention.

FIG. 7 is a conceptual cross-sectional view showing a scanner as one embodiment of an image reading device built-in device of the present invention.

[Explanation of symbols]

11 ... Translucent airtight container, 13A ... Electrode, 13B ... Electrode,
C2 ... Capacitor, CC1 ... Control unit, CC2 ... Control unit,
DC1 ... DC power supply, DC2 ... DC power supply, DDL ... Discharge lamp, OC1 ... Lighting circuit section, OC2 ... Lighting circuit section, R3
... Variable resistance resistor, SYC1 ... Synchronous signal receiver, S
YC2 ... Sync signal receiver

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H109 AA02 AA15 AA23                 3K072 AA10 AC01 AC11 BB01 BC02                       CA16 GA02 GB03 HA09 HA10                 5C051 AA01 BA03 DA03 DB07 DB28                       DC05 DE29 EA01 FA00                 5C072 AA01 BA19 CA04 CA11 EA05                       XA10

Claims (2)

[Claims] 1. An oscillation frequency is adjusted so as to have a capacitor and a variable resistance resistor, and the variable resistance resistor is operated so that a predetermined number of triangular waves are generated during one period of a synchronizing signal described later. A control unit having a triangular wave generating circuit and a drive signal generating circuit for generating a PWM-controlled drive signal based on the triangular wave generated from the triangular wave generating circuit;
A synchronization signal receiving unit that temporarily stops the operation of the control unit each time a synchronization signal is received; a DC power supply; a switching element whose switching is controlled by a drive signal generated from the control unit; Equipped with an output transformer having a secondary winding, the switching element and the primary winding of the output transformer are connected in series to a DC power supply, and the repetitive waveform is applied to the secondary winding of the output transformer as the switching element switches. A lighting circuit section for outputting an output voltage of a transparent transparent airtight container, a phosphor layer formed on the inner surface of the transparent airtight container having a three-wavelength emission type phosphor as a main component, and inside the transparent airtight container. A discharge lamp containing a sealed rare gas as a main component, and a pair of electrodes, and a discharge lamp that is lit by applying an output voltage of a lighting circuit unit between the pair of electrodes; Discharge lamp lighting apparatus, characterized in that there. 2. A source image is read in a predetermined cycle, and
An image reading device built-in device main body having an image reading device for generating a synchronizing signal; and an image reading device set so that the synchronizing signal receiving unit receives the synchronizing signal generated by the image reading device of the image reading device built-in device body. An apparatus incorporating an image reading apparatus, comprising: the discharge lamp lighting device according to claim 1, which is disposed in the main body of the embedded device to illuminate an original image.