JP4925299B2 - Discharge lamp fixtures - Google Patents

Description

  The present invention relates to a discharge lamp apparatus using a cold cathode discharge lamp as a light source.

  2. Description of the Related Art In recent years, various types of discharge lamp fixtures have been provided that use a cold cathode discharge lamp (cold cathode fluorescent lamp) that is smaller and has higher luminance than a hot cathode fluorescent lamp as a light source. For example, as a kind of discharge lamp fixture, a so-called high-intensity guide lamp using a cold cathode fluorescent lamp as a light source is provided.

  As this type of high-intensity guide lamp, as shown in FIGS. 8 to 12, a lamp body 10 holding a front-opening instrument body 10, a display unit 20 attached to the front face of the instrument body 10, and a cold cathode fluorescent lamp 3 is used. A light guide plate type (or panel type) provided with a holder unit 30 is provided (see, for example, Patent Document 1). Here, a lighting device 4 for turning on the cold cathode fluorescent lamp 3 is housed in the instrument main body 10. In addition, the display unit 20 includes a display panel 21 and a light guide plate (not shown) disposed on the rear surface side of the display panel 21, and the cold cathode fluorescent lamp 3 disposed opposite to the upper edge of the light guide plate. The light is incident on the light diffusion portion provided on the rear surface of the light guide plate while being guided to the lower edge of the light guide plate by total reflection in the light guide plate, and the light that is diffused by the light diffusion portion is directed toward the display panel 21. The light is emitted to the front of the display panel 21. The lamp holder unit 30 includes the cold cathode fluorescent lamp 3, the reflection plate 32, and a lamp holder 31 that is a unit main body for holding the cold cathode fluorescent lamp 3, and in the state where the display unit 20 is attached to the fixture main body 10, Is attached to the front surface of the instrument main body 10 in a detachable manner so as to cover the front opening of the instrument main body 10 together with the display unit 20 (see FIG. 9).

  The lamp holder unit 30 includes a front plate 31a located on the front side of the instrument body 10, an upper plate 31b formed integrally and continuously from the upper end edge of the front plate 31a toward the rear, and both side edges of the front plate 31a. A pair of side plates 31c projecting rearward and a pair of supports projecting downward at both ends of the upper plate 31b and supporting the metal (for example, aluminum) reflector 32 and the cold cathode fluorescent lamp 3 A lamp holder 31 is provided as a unit body made of synthetic resin, which is integrally formed with the bases 35 and 35. The lamp holder unit 30 has both ends of a cold cathode fluorescent lamp 3 that is a straight tube lamp supported by a pair of support bases 35 and 35 of the lamp holder 31, and electrodes (not shown) of the cold cathode fluorescent lamp 3. A synthetic resin holder block (not shown) in which connection terminals 36 and 36 connected to the lead wires 3b and 3b protruding from both ends are detachably coupled to the support bases 35 and 35 from the lower surface side. And protrudes rearward of the lamp holder 31. The reflecting plate 32 is supported by the support bases 35 and 35 so as to surround the cold cathode fluorescent lamp 3 and has a U-shaped cross section with an open lower surface. Here, the cold cathode fluorescent lamp 3 and the reflector 32 are held between the lamp holder 31 and the holder block by coupling a pair of holder blocks to the support bases 35 and 35 of the lamp holder 31. .

  On the other hand, on the inside of the upper part of both side walls in the fixture body 10, connectors 50, 50 are connected to the lighting device 4 via electric wires 53, 53, respectively, and the connection terminals 36, 36 of the lamp holder unit 30 are inserted and connected from the front. Is arranged. Each connector 50 has a terminal insertion port 50b opened at both ends in the longitudinal direction of an insulating cover 50a formed in a rectangular parallelepiped shape, and a terminal insertion port is formed in the cover 50a at a portion corresponding to the terminal insertion port 50b. A blade receiver 51 for receiving the connection terminal 36 inserted from 50b is housed. Each connector 50 is connected to the lighting device 4 via two electric wires 53, and the cold cathode fluorescent lamp 3 is electrically connected to the lighting device 4 via the electric wires 53 and the connector 50. And as shown in FIG. 12, the lead wire holding part 14 which hold | maintains in the state which separated the two electric wires 53 so that a leakage current may not be generated in the front side of the rear wall of the instrument main body 10 is provided suitably. Thus, the wiring position of the electric wire 53 connecting between the connector 50 and the lighting device 4 in the appliance body 10 can be standardized, and it is necessary to make the length of the electric wire 53 extra long in consideration of workability and the like. Since the electric wire 53 can be wired at the time of shipment from the factory, it is not necessary for the contractor to perform the wiring process when the lamp holder unit 30 is installed, and the installation is facilitated, and the leakage current varies depending on the contractor. Such a thing disappears.

  As shown in FIG. 13, the lighting device 4 smoothes the voltage conversion circuit 4 a that converts the pulsating voltage to a voltage lower than the power supply voltage (100 V) of the commercial AC power supply AC, and the pulsating voltage converted by the voltage conversion circuit 4 a. The smoothing circuit 4b, the charging circuit 4c for charging the secondary battery 4d with the DC voltage output from the smoothing circuit 4b, and the DC voltage output from the smoothing circuit 4b or the secondary battery 4d at a frequency higher than the commercial power supply frequency. Inverter circuit INV for converting to AC voltage, and normally, the input terminal of inverter circuit INV is connected to the output terminal of smoothing circuit 4b, and when the commercial AC power supply AC fails, the input terminal of inverter circuit INV is connected to smoothing circuit 4b. And a changeover switch portion S that is disconnected from the output end and connected to both electrodes of the secondary battery 4d.

  The inverter circuit INV is constituted by, for example, a self-pulsation type push-pull inverter circuit as shown in FIG. 14, and a high voltage (starting voltage) is supplied via a ballast capacitor C0 connected to the secondary side of the transformer T at the time of starting. Is applied to start the cold cathode fluorescent lamp 3, and after the start, the ballast capacitor C0 serves as a current limiting element, so that a substantially constant high-frequency alternating current can be supplied to the cold cathode fluorescent lamp 3. Further, the cold cathode fluorescent lamp 3 can be dimmed by adjusting the voltage of the DC voltage supplied to the inverter circuit INV or by intermittently switching the DC voltage at a frequency of several tens to several hundreds of Hz. However, since the self-pulsation type push-pull inverter circuit is well known in the art, a detailed configuration and description of the operation are omitted.

  By the way, in the circuit configuration shown in FIG. 14, a protection circuit 4e is provided that stops the inverter circuit INV when the electrical connection between the cold cathode fluorescent lamp 3 and the lighting device 4 is released. The protection circuit 4e monitors the current output from the inverter circuit INV. If the current does not flow because the cold cathode fluorescent lamp 3 is not connected, the protection circuit 4e controls the changeover switch S to control the direct current voltage to the inverter circuit INV. The inverter circuit INV is stopped by opening the power supply path. However, since a high voltage is applied to the connection terminal 36 and the connector 50 that electrically connect the cold cathode fluorescent lamp 3 and the lighting device 4, for example, the connection terminal 36 and the connector 50 are separated by a small distance. In a situation where they are separated from each other, an abnormal discharge such as a spark discharge or a glow discharge is generated between the connection terminal 36 and the connector 50, and the current continues to flow from the lighting device 4 to the cold cathode fluorescent lamp 3 for protection. There is a possibility that the circuit 4e does not operate.

On the other hand, Patent Document 2 focuses on the point that a pulsed high voltage, which is much higher than the open circuit voltage when a spark discharge occurs, is superimposed on the lamp voltage. A technique of detecting and stopping an inverter circuit is disclosed. Further, Patent Document 1 discloses that an executor indicates that the lamp holder unit 30 is completely attached to the instrument body 10 by generating a clicking sound when the lamp holder unit 30 is completely attached to the instrument body 10. It can be confirmed by clicking sound.
JP 2002-23657 A JP 2005-5059 A

  However, it is impossible to completely prevent the lamp holder unit 30 from being attached to the instrument body 10 in an incomplete state, that is, the connection terminal 36 and the connector 50 being in an incomplete connection state. Moreover, since the cold cathode discharge lamp does not have a filament unlike the hot cathode discharge lamp, for example, it is not possible to confirm the connection state based on whether or not a minute current flows through the filament before starting. Whether or not the connection is incomplete must be determined based on the later characteristics and changes. Then, when the lighting device 4 is started in a state where the connection terminal 36 and the connector 50 are incompletely connected, the cold cathode fluorescent lamp 3 may be lit, and it may not be noticed from the appearance that a connection abnormality has occurred. There is. Moreover, if such an incomplete connection state continues for a long time, problems such as abnormal heat generation occur. In the prior art described in Patent Document 2, a high voltage superimposed on the output voltage of the lighting device 4 is detected when an abnormal discharge such as a spark discharge occurs. Standards for judging whether or not the connection is incomplete because the variation including the temperature characteristics of the lighting voltage during normal lighting is very wide and varies depending on the location of the abnormal discharge and the gap distance. Setting the value is very difficult.

  The present invention has been made in view of the above circumstances, and its purpose is a defect caused by an incomplete connection state between a connection terminal connected to an electrode of a cold cathode discharge lamp and a connector connected to a lighting device. An object of the present invention is to provide a discharge lamp apparatus capable of preventing the occurrence of the above.

In order to achieve the above object, a first aspect of the present invention is a discharge lamp apparatus having a straight tube type cold cathode discharge lamp as a light source, a lamp holder for holding the cold cathode discharge lamp at both ends, a cold cathode discharge lamp, A lighting device that illuminates an electric lamp, a fixture main body that supports the lighting device and to which a lamp holder is detachably attached, and a pair of electrodes provided at both ends of the cold cathode discharge lamp, which are electrically connected to each other and the lamp holder The pair of first connection terminal portions supported by the lamp and the output side of the lighting device are electrically connected, and are electrically connected to the pair of first connection terminal portions when the lamp holder is attached to the fixture body. The lighting device includes: a pair of first connectors; and an electric circuit supported by the lamp holder and having an electric characteristic that changes according to a connection state between the first connection terminal portion and the first connector. The characteristic Comprising a circuit output, and a protection circuit that stops the output of the lighting device when the first connector and the first connection terminal portion is estimated to be in an incomplete connection state based on the detection result of the detection circuit, the electrical The circuit includes a plurality of impedance elements inserted in series between the pair of first connection terminal portions, and a second connection terminal electrically connected to any connection point of the plurality of impedance elements and supported by the lamp holder. And a second connector that is electrically connected to the second connection terminal when the lamp holder is attached to the instrument body .

According to a second aspect of the present invention, in the first aspect of the invention, the impedance element includes a reflector that is supported by the lamp holder and reflects light emitted from the cold cathode discharge lamp.

According to the first aspect of the present invention, if the first connection terminal portion and the first connector are in an incompletely connected state with the lamp holder being attached to the fixture body, the first connection terminal portion and the first connector are Since the electrical characteristics of the electrical circuit change compared to when it is in a completely connected state, the change in the electrical characteristics is detected by the detection circuit, and the protection circuit is connected to the first connection terminal portion based on the detection result of the detection circuit. If it is presumed that the first connector is in an incomplete connection state, the output of the lighting device is stopped to connect the connection terminal (first connection terminal portion) connected to the electrode of the cold cathode discharge lamp to the lighting device. It is possible to prevent the occurrence of defects due to an incomplete connection state with the connector (first connector). In addition, it is not necessary to make the structures of the first connection terminal portion and the first connector complicated.

According to the second aspect of the present invention, the structure of the lamp holder can be simplified and the cost can be reduced as compared with a case where an impedance element is separately provided by using the reflector as an impedance element.

  Hereinafter, an embodiment in which the technical idea of the present invention is applied to a guide light described in the prior art will be described in detail with reference to the drawings. However, the discharge lamp fixture according to the present invention is not limited to the guide lamp, and the technical idea of the present invention can be applied to all discharge lamp fixtures other than the guide lamp.

(Embodiment 1)
The basic structure of the guide light of this embodiment is the same as the conventional example shown in FIGS. Therefore, the same components as those in the conventional example are denoted by the same reference numerals, and illustration and description thereof are omitted as appropriate.

  In this embodiment, as shown in FIG. 1B, each of the connection terminal portions 36 and 36 has two contacts (a first contact 36a and a second contact 36b), and each connector 50 includes A pair of blade receivers (a first blade receiver 51a and a second blade receiver 51b) that selectively receive the two contacts 36a and 36b of the connection terminal portion 36 are provided. The two contacts 36 a and 36 b are arranged in a line along the axial direction of the cold cathode fluorescent lamp 3 (left and right direction in FIG. 1B), and the first contact 36 a is an electrode of the cold cathode fluorescent lamp 3. And the second contact 36 b is connected to the reflector 32. The pair of blade receivers 51 a and 51 b of the connector 50 are also arranged in a line along the axial direction of the cold cathode fluorescent lamp 3, and the first blade receiver 51 a is connected via the electric wire 53 as shown in FIG. Are electrically connected to the output terminal of the inverter circuit INV, and the second blade receiver 51 b is electrically connected to the detection circuit 70 via the electric wire 54. In other words, in the present embodiment, the metal reflector 32 corresponds to an impedance element, and the second contactors 36b and 36b and the impedance element (reflector 32) inserted between the second contacts 36b and 36b are electrically connected. A circuit is configured.

  As shown in FIG. 1A, the lighting device 4 includes a DC power source DC, a changeover switch unit S, an inverter circuit INV, a detection circuit 70, and a protection circuit 71. The DC power source DC is composed of the voltage conversion circuit 4a, the smoothing circuit 4b, the secondary battery 4d, and the charging circuit 4c in the circuit diagram of the conventional example shown in FIG. Further, the illustration of the changeover switch portion S is simplified. In the following description, the connector 50 connected to the output terminal on the high potential side of the inverter circuit INV is expressed as 50A, and the connector 50 connected to the output terminal on the low potential side of the inverter circuit INV is expressed as 50B. To do.

  The detection circuit 70 includes resistors R1, R2 connected in series between the second blade receiver 51b of the low-potential side connector 50B and the ground, and a high frequency connected between the connection point of the resistors R1, R2 and the ground. Voltage dividing resistors R3 and R4 for dividing the noise cutting capacitor C1, the control power supply Vcc (for example, a DC voltage of about 5V stabilized by a three-terminal regulator) to create the reference voltage Vref, and the resistor R1 , R2 and the comparator CP that compares the potential difference (detection voltage) Vi between the ground and the reference voltage Vref. If the detection voltage Vi is higher than the reference voltage Vref, the output of the comparator CP is set to the H level. If Vi is equal to or lower than the reference voltage Vref, the output of the comparator CP is set to L level. That is, if the connection state between the connection terminal portions 36 and 36 and the connectors 50 and 50 is normal (complete), a current is supplied from the control power source Vcc to the impedance element (reflector 32) via the pair of connection terminal portions 36 and the connector 50. Since the detection voltage Vi higher than the reference voltage is obtained by flowing, the output of the detection circuit 70 becomes H level. However, if the connection state between the connection terminal portions 36 and 36 and the connectors 50 and 50 is incomplete, a current is passed through the impedance element. Does not flow, the detection voltage Vi becomes substantially zero, so the output of the detection circuit 70 becomes L level.

  When the output of the detection circuit 70 (output of the comparator CP) becomes L level, the protection circuit 71 turns off the changeover switch section S to open the power supply path from the DC power source DC and stop the inverter circuit INV. When the output of 70 becomes H level, the selector switch S is turned on to close the power supply path from the DC power source DC and operate the inverter circuit INV.

  Therefore, when at least one of the pair of connection terminals 36 and 36 and the connectors 50 and 50 is in an incomplete connection state, the output of the detection circuit 70 becomes L level and the protection circuit 71 operates the inverter circuit INV. Since it stops, it is possible to prevent the cold cathode fluorescent lamp 3 from being continuously lit in an incompletely connected state.

  By the way, as shown in FIG. 2, the second contactor 36 b is shortened with respect to the first contactor 36 a and the second contactor 36 b is the first contactor along the longitudinal direction of the cold cathode fluorescent lamp 3. If the pair of contacts 36a and 36b are arranged in a row so as to be outside of 36a, when the lamp holder unit 30 is removed from the instrument main body 10, the first contact 36a having a long dimension becomes the first blade receiver 51a. Since the second contactor 36b having a short dimension is separated from the second blade support 51b in a state of being in contact with the detection circuit 70, the detection circuit 70 detects an incomplete connection state, and the protection circuit 71 stops the operation of the inverter circuit INV. It is possible to prevent abnormal discharge from occurring between the connection terminal portion 36 and the connector 50 during the period up to. Further, when the lamp holder unit 30 is removed from the fixture body 10, the connection terminal portions 36 at both ends are rarely removed from the respective connectors 50 at the same time. In general, one connection terminal portion 36 and the connector 50 are connected to each other. Since the other connection terminal portion 36 and the connector 50 are removed after being removed first, only the connection terminal portion 36 and the connector 50 on one side are often in an incompletely connected state. Therefore, as shown in FIG. 2, the second contactor 36b connected to the detection circuit 70 is located far from the cold cathode fluorescent lamp 3 with respect to the first contactor 36a (an outer position in the lamp holder unit 30). In this case, the incomplete connection state can be detected more quickly and reliably, and the operation of the inverter circuit INV can be stopped.

  In the present embodiment, the reflecting plate 32 is used as the impedance element constituting the electric circuit. However, a resistance element or the like built in the lamp holder unit 30 may be used as the impedance element. Further, if the resistance values of the resistors R1 and R2 of the detection circuit 70 are adjusted according to the equivalent resistance value of the impedance element, the current consumption of the detection circuit 70 can be suppressed. Furthermore, the circuit configuration of the detection circuit 70 is not limited to the present embodiment, and any circuit can be used as long as it can confirm conduction between the second blade supports 51b and 51b.

  Here, in this embodiment, since the electric circuit (the impedance element including the second contacts 36b and 36b and the reflector 32) and the cold cathode fluorescent lamp 3 are electrically independent from the lighting device 4, the lighting device Even when the cold cathode fluorescent lamp 3 is not supplied with power from 4, detection by the detection circuit 70 is possible. Moreover, since the voltage detected by the detection circuit 70 is a low voltage (about 5 V of the control voltage Vcc), the detection circuit 70 can be realized with a simple and inexpensive configuration. Miniaturization can be achieved.

(Embodiment 2)
In the first embodiment, it is necessary to change the structure of the pair of connection terminal portions 36 and 36 of the lamp holder unit 30 and the structure of the pair of connectors 50 and 50 of the instrument body 10 from the conventional example. On the other hand, in the present embodiment, a pair of connection terminal portions (hereinafter referred to as first connection terminal portions) 36 and 36 and a pair of connectors (hereinafter referred to as first connectors) 50 and 50 are provided. Is substantially the same as the conventional example, and separately, the second connection terminal portion 37 is provided in the lamp holder unit 30 and the second connector 52 detachably connected to the second connection terminal portion 37 is provided in the instrument body 10. However, since the basic configuration is the same as that of the first embodiment, the same reference numerals are assigned to the common components, and illustration and description thereof are omitted as appropriate.

  As shown in FIG. 3B, the first connection terminal portion 36 is composed of one contact, and the electrode of the cold cathode fluorescent lamp 3 and the reflection plate 32 as an impedance element are electrically connected. On the other hand, the first connector 50 has one blade receiver 51, and this blade receiver 51 is electrically connected to the output terminal of the inverter circuit INV via the electric wire 53. Although not shown, a second connection terminal portion 37 made of one contact is provided at the center in the longitudinal direction of the lamp holder unit 30 as well as the first connection terminal portion 36, Connected. On the other hand, the second connector 52 is provided at the center in the width direction of the fixture body 10 (the direction along the longitudinal direction of the lamp holder unit 30) and is electrically connected to the detection circuit 70 (see FIG. 3A). ).

  Here, since the pair of first connection terminal portions 36A and 36B are electrically connected to both ends of the reflection plate 32 and the second connection terminal portion 37 is electrically connected to the center of the reflection plate 32, FIG. As shown to (a), the equivalent circuit of the electric circuit in this embodiment includes an impedance element Z1 inserted between the first connection terminal portion 36A and the second connection terminal portion 37 on the high potential side, It is represented by a series circuit with an impedance element Z2 (= Z1) inserted between the connection terminal portion 37 and the first connection terminal portion 36b on the low potential side, and the output voltage of the inverter circuit INV is expressed by the impedance elements Z1 and Z2. The divided voltage is input to the detection circuit 70. However, since the output voltage of the inverter circuit INV reaches about several hundred V to 2,000 V (effective value), in order to keep the leakage current to the detection circuit 70 low, the impedance values of the impedance elements Z1 and Z2 may be set to several MΩ. desirable.

  The detection circuit 70 rectifies the potential difference between the connection point of the resistors R1 and R2 inserted between the second connector 52 and the ground and the ground by the diode D1 and smoothes the rectified voltage by the capacitor C1. The voltage Vi is obtained, and the detected voltage Vi is compared with the reference voltage Vref by the comparator CP.

  Thus, when the connection state between the first connection terminal portions 36 and 36 and the first connectors 50 and 50 is normal (complete), the output voltage of the inverter circuit INV is changed to the first connection terminal portions 36 and 36 and the first connector 50. , 50 to be applied to the impedance elements Z1, Z2 (reflecting plate 32) and a detection voltage Vi higher than the reference voltage Vref is obtained, so that the output of the detection circuit 70 becomes H level. , 36 and the first connectors 50, 50 are incompletely connected, the output voltage of the inverter circuit INV is not applied to the impedance elements Z1, Z2, and therefore the detection voltage Vi becomes substantially zero. L level. Therefore, if the low potential side first connection terminal portion 36B and the first connector 50B or the second connection terminal portion 37 and the second connector 52 are in an incompletely connected state, the output of the detection circuit 70 becomes L level for protection. Since the circuit 71 stops the operation of the inverter circuit INV, it is possible to prevent the cold cathode fluorescent lamp 3 from being continuously lit in an incompletely connected state.

  As described above, according to the present embodiment, the structure of the first connection terminal portions 36 and 36 and the first connectors 50 and 50 is substantially the same as that of the conventional example, so that the cost can be reduced as compared with the first embodiment. Moreover, since the 2nd connection terminal part 37 is arrange | positioned in the longitudinal direction center of the lamp holder unit 30, when providing the lamp holder unit 30 and the display unit 20 on both surfaces of the instrument main body 10, for example, as shown in FIG. Moreover, the structure of the lamp holder unit 30 in each surface can be made the same. In the configuration of the first embodiment, it is possible to share the lamp holder unit 30 in the double-sided type. However, in the first embodiment, the detection circuit 70 uses the control power source Vcc, so that the appliance is considered in consideration of leakage current and the like. It is necessary to pay attention to the arrangement method of the wires 54 and 54 on each surface of the main body 10.

  However, although the voltage dividing ratio of the impedance elements Z1 and Z2 is not particularly limited, it is desirable to set it to about one half in consideration of application to a double-sided type induction lamp as shown in FIG. Thus, the constant setting of the detection circuit 70 on each surface and the design of the lamp holder unit 30 can be made common on both surfaces. Further, the circuit configuration of the detection circuit 70 is not limited to the present embodiment, and any circuit can be used as long as conduction between the first connector 50 and the second connector 52 can be confirmed.

(Embodiment 3)
In the second embodiment, the pair of first connection terminal portions 36 are electrically connected to both longitudinal ends of the reflection plate 32 and the second connection terminal portions 37 are electrically connected to the center of the reflection plate 32 in the longitudinal direction. Although a series circuit of impedance elements Z1 and Z2 including a reflector 32 is connected in parallel with the electrode of the fluorescent lamp 3, in the present embodiment, the first connection terminal portion 36 and the reflector 32 are insulated to provide cold cathode fluorescence. A characteristic is that a potential difference generated between the reflector 32 and the ground due to the parasitic capacitance between the lamp 3 and the reflector 32 is taken out from the second connection terminal portion 37.

  As shown in FIG. 5, the first connection terminal portion 36 is connected only to the electrode of the cold cathode fluorescent lamp 3 and is insulated from the reflector 32. On the other hand, the second connection terminal portion 37 is electrically connected to the longitudinal center of the reflection plate 32. The first connector 50 is connected to the output end of the inverter circuit INV, and the second connector 52 is electrically connected to the input end of the detection circuit 70. Here, the contact length of the second connection terminal portion 37 is shorter than the contact length of the first connection terminal portion 36.

  Here, since the output voltage of the inverter circuit INV reaches about several hundreds V to 2,000 V (effective value), the impedance value of the cold cathode fluorescent lamp 3 is several tens kΩ to 100 kΩ, and the lighting frequency is several tens kHz. It is electrostatically induced by the parasitic capacitance between the fluorescent lamp 3 and the reflecting plate 32, and a potential difference is generated between the reflecting plate 32 and the ground. In particular, when the reflecting plate 32 is made of metal, a significant potential difference occurs.

  Thus, as shown in FIG. 5B, if the connection state between the first connection terminal portions 36 and 36 and the first connectors 50 and 50 is normal (complete), the output voltage of the inverter circuit INV is the first connection. When applied to the cold cathode fluorescent lamp 3 through the terminal portions 36 and 36 and the first connectors 50 and 50, a potential difference due to electrostatic induction occurs between the reflector 32 and the ground, and the detection voltage is higher than the reference voltage Vref. Vi is obtained and the output of the detection circuit 70 becomes H level, but the connection state between the first connection terminal portions 36 and 36 and the first connectors 50 and 50 is incomplete as shown in FIG. Since the output voltage of the inverter circuit INV is not applied to the cold cathode fluorescent lamp 3, a potential difference due to electrostatic induction does not occur between the reflector 32 and the ground, and the detection voltage Vi becomes substantially zero. Level (see FIG. 6). Accordingly, if the first connection terminal portion 36 and the first connector 50 are in an incompletely connected state, the output of the detection circuit 70 becomes L level and the protection circuit 71 stops the operation of the inverter circuit INV. It is possible to prevent the cold cathode fluorescent lamp 3 from being kept on in the connected state.

  As described above, according to the present embodiment, there is an advantage that safety can be improved since it is not necessary to apply the output voltage of the inverter circuit INV to the reflector 32 as in the second embodiment. Further, since the second connection terminal portion 37 is arranged at the center in the longitudinal direction of the lamp holder unit 30, even when the lamp holder unit 30 and the display unit 20 are provided on both surfaces of the fixture body 10 as in the second embodiment, respectively. The configuration of the lamp holder unit 30 on the surface can be the same. When the lamp holder unit 30 is removed from the fixture body 10, the contact of the first connection terminal portion 36 having a long dimension is in contact with the blade receiver of the first connector 51 and the second connection terminal portion 37 having a short dimension is removed. Since the contact is separated from the second connector 52, an incomplete connection state can be detected more reliably and promptly. Further, the circuit configuration of the detection circuit 70 is not limited to the present embodiment as long as it can detect the potential difference between the reflector 32 and the ground.

(Embodiment 4)
A circuit configuration of the present embodiment is shown in FIG. However, the present embodiment is characterized by the configuration of the detection circuit 70, and the other configurations are the same as the conventional example. Accordingly, the same components as those in the conventional example are denoted by the same reference numerals, and illustration and description thereof are omitted as appropriate.

  In the lamp holder unit 30, the impedance element Z is connected in parallel with the cold cathode fluorescent lamp 3 to the connection terminal portion 36A on the high potential side and the connection terminal portion 36B on the low potential side to constitute an electric circuit. However, the impedance element Z may be the reflection plate 32.

  The detection circuit 70 in the present embodiment includes a detection resistor Rs connected in series with a current detection resistor Rx between the secondary side of the transformer T constituting the inverter circuit INV and the low-potential side connector 50B, and a detection resistor An integrating circuit comprising a diode D1 having an anode connected to the connection point of Rs and the connector 50B, a capacitor C1 inserted between the secondary side of the transformer T and the connection point of the connector 50B and the cathode of the diode D1, and a resistor R2. And a comparator CP that compares the detection voltage Vi and the control voltage Vcc, which are input via the integration circuit, with a reference voltage Vref created by dividing the voltage by the voltage dividing resistors R3 and R4. Note that both ends of the detection resistor Rs can be short-circuited so as to be freely opened and closed by a switch SW1.

  On the other hand, in the protection circuit 71 in the present embodiment, the power supply voltage of the DC power supply DC is set to a voltage lower than normal before starting the cold cathode fluorescent lamp 3, so that a voltage sufficiently lower than the starting voltage is obtained from the inverter circuit INV. If the connection state between the connection terminal portions 36A and 36B and the connectors 50A and 50B is not incomplete, the inverter circuit INV, the connection terminal portion 36A, the impedance element Z, the connection terminal portion 36B, the detection resistor Rs, the resistance Rx, and the inverter A current is passed through the circuit INV. Here, since the impedance value of the impedance element Z is set to be very high compared to the impedance value of the cold cathode fluorescent lamp 3 at the time of lighting so that the leakage current flowing through the impedance element Z at the time of steady lighting is reduced. Since the current flowing through the path becomes very small, it is difficult to detect with the current detection resistor Rx whose resistance value is set low in order to suppress current consumption during steady lighting. Therefore, in the detection circuit 70 of the present embodiment, a detection resistor Rs having a resistance value sufficiently higher than that of the resistor Rx is connected in series with the resistor Rx, and a voltage drop generated between both ends of the resistor Rx and the detection resistor Rs is detected by the diode D1. The detected voltage Vi is rectified and smoothed by an integrating circuit, and this detected voltage Vi is compared with the reference voltage Vref by the comparator CP.

  Thus, before the cold cathode fluorescent lamp 3 is started, the protection circuit 71 sets the power supply voltage of the DC power supply DC to a voltage lower than the normal voltage so that the output voltage of the inverter circuit INV is sufficiently lower than the starting voltage. In this state, the detection circuit 70 compares the detection voltage Vi with the reference voltage Vref. If the connection state between the connection terminal portions 36A and 36B and the connectors 50A and 50B is complete, the detection voltage Vi becomes higher than the reference voltage Vref and the output voltage of the detection circuit 70 becomes H level. The power supply voltage of the DC power supply DC is increased to the normal voltage by judging that the connection state is normal, thereby raising the output voltage of the inverter circuit INV to the starting voltage, starting the cold cathode fluorescent lamp 3, and further switching the switch SW1. By closing and short-circuiting both ends of the detection resistor Rs, wasteful power consumption is suppressed. On the other hand, if the connection state between the connection terminal portions 36A and 36B and the connectors 50A and 50B is incomplete, the detection voltage Vi is equal to or lower than the reference voltage Vref, so that the output voltage of the detection circuit 70 becomes L level. Is incompletely connected, and the selector switch S is turned off to open the power supply path from the DC power source DC and stop the inverter circuit INV.

  As described above, according to the present embodiment, the connection state between the connection terminal portions 36A and 36B and the connectors 50A and 50B is detected before the cold cathode fluorescent lamp 3 is started. The operation of the inverter circuit INV can be stopped to improve safety. Moreover, a plurality of contacts 36a and 36b are provided on the connection terminal portion 36 as in the first embodiment, and at the same time a plurality of blade receivers 51a and 51b are provided in the connector 50, or the first connection as in the second and third embodiments. Since the second connection terminal portion 37 is provided in the lamp holder unit 30 in addition to the terminal portions 36A and 36B, it is not necessary to provide the second connector 52 in the fixture body 10 in addition to the first connectors 50A and 50B. Compatibility with the holder unit 30 and the instrument body 10 can be maintained. However, when the connection state between the connection terminal portions 36A and 36B and the connectors 50A and 50B is incomplete while the cold cathode fluorescent lamp 3 is lit, the current flowing through the resistor Rx is smaller than that during steady lighting. By detecting the protection circuit 71 and turning off the changeover switch section S, the power supply path from the DC power source DC is opened to stop the inverter circuit INV.

  In the first to fourth embodiments described above, the self-excited oscillation type push-pull inverter circuit common to the conventional example is illustrated as the inverter circuit INV. However, the present invention is not limited to this. For example, a half-bridge type or a full-bridge type It may be an inverter circuit.

1 shows Embodiment 1 of the present invention, in which (a) is a schematic circuit configuration diagram, and (b) is a cross-sectional view showing the main parts of a lamp holder unit and an instrument body. It is sectional drawing which shows the principal part of the lamp holder unit and instrument main body in another structure same as the above. Embodiment 2 of this invention is shown, (a) is a schematic circuit block diagram, (b) is sectional drawing which shows the principal part of a lamp holder unit and an instrument main body. It is sectional drawing which shows the principal part of the lamp holder unit and instrument main body in another structure same as the above. (A), (b) is sectional drawing which shows the principal part of the lamp holder unit and instrument main body in Embodiment 3 of this invention. It is a schematic circuit block diagram same as the above. It is a schematic circuit block diagram of Embodiment 4 of this invention. It is a disassembled perspective view of a prior art example. It is a disassembled perspective view which shows the principal part of a lamp holder unit and an instrument main body in the same as the above. It is sectional drawing which shows the principal part same as the above. It is sectional drawing which shows the principal part of a lamp holder unit and an instrument main body in the same as the above. It is a partially broken front view same as the above. It is a circuit diagram of the lighting device in the same as the above. It is a circuit diagram of the inverter circuit in the same as the above.

Explanation of symbols

3 Cold cathode fluorescent lamp (cold cathode discharge lamp)
4 lighting device 10 fixture body 30 lamp holder unit 36 connection terminal 36a first contact 36b second contact 50 connector 51a first blade support 51b second blade support 70 detection circuit 71 protection circuit S changeover switch INV Inverter circuit

Claims (2)

A discharge lamp apparatus having a straight tube type cold cathode discharge lamp as a light source, a lamp holder for holding the cold cathode discharge lamp at both ends, a lighting device for lighting the cold cathode discharge lamp, and a lamp that supports the lighting device and supports the lamp A fixture main body to which the holder is detachably attached, a pair of first connection terminal portions that are electrically connected to a pair of electrodes provided at both ends of the cold cathode discharge lamp and supported by the lamp holder, and a lighting device And a pair of first connectors electrically connected to the pair of first connection terminal portions when the lamp holder is attached to the fixture body, and supported by the lamp holder, An electrical circuit whose electrical characteristics change according to the connection state between the connection terminal portion and the first connector;
The lighting device is turned on when it is estimated that the first connection terminal portion and the first connector are in an incompletely connected state based on a detection circuit that detects an electrical characteristic of the electric circuit and a detection result of the detection circuit. A protection circuit for stopping the output of the device ,
The electrical circuit includes a plurality of impedance elements inserted in series between a pair of first connection terminal portions, and a second electrically connected to any connection point of the plurality of impedance elements and supported by the lamp holder. A discharge lamp device comprising a connection terminal portion, and a second connector electrically connected to the second connection terminal portion when the lamp holder is attached to the device body . 2. The discharge lamp apparatus according to claim 1 , wherein the impedance element comprises a reflector that is supported by the lamp holder and reflects light emitted from the cold cathode discharge lamp .

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