JP2012169178A - Lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the life of a lighting device by reducing application of an excessive load to a lighting circuit even when a halogen lamp is in the end-of-life state.SOLUTION: A lighting device 1 comprises a halogen lamp 2 as a light source, and a lighting circuit 10 which supplies lighting power to the halogen lamp 2. The lighting circuit 10 is connected with a life detection circuit 11 and a current application circuit 12. When the end-of-life state of the halogen lamp 2 is detected by the life detection circuit 11, the current application circuit 12 feeds a current required for disconnecting the filament of the halogen lamp 2 to the halogen lamp 2 to disconnect the filament. Consequently, driving of the lighting circuit 10 is stopped, and overcurrent flowing into the lighting circuit 10 subsequently can be reduced to prolong the life of the lighting device 1.

Description

  The present invention relates to a lighting device mainly using a halogen lamp as a light source.

  2. Description of the Related Art Conventionally, apparatuses using a halogen lamp as a light source have been provided in illumination apparatuses and copying apparatuses. In this type of apparatus, in order to enable the halogen lamp to be used stably until the end of its life, it is proposed to provide a soft start mechanism that reduces the inrush current flowing in the filament of the halogen lamp at the start of lighting (for example, , See Patent Document 1).

  The halogen lamp control device described in Patent Document 1 incorporates a soft start circuit that gradually increases the supply voltage to the halogen lamp until the temperature of the filament of the halogen lamp reaches a predetermined set value. Accordingly, it is possible to reduce an excessive load applied to the filament at the start of lighting and to use the halogen lamp stably until the end of the life of the halogen lamp.

  By the way, there are mainly four types of halogen lamp lifetimes, namely, a decrease in illuminance due to blackening of the bulb, a break in the filament, a coil short in the filament, and a failure in the lamp seal portion. Conventionally, tungsten halide evaporated from the filament gathers at a low temperature portion, and the high temperature portion of the filament is thinned and the filament is disconnected, and in most cases, the lifetime is reached. However, in recent years, there has been an increase in the number of cases where a lighting device using a halogen lamp as a light source is used continuously for a long period of time without being turned on and off, and the number of cases where the life of the lighting device is shortened due to the coil coil shorting.

  The coil short circuit of the filament is caused by the fact that the tungsten halide of the filament repeatedly evaporates and adheres so that the shape of the filament is rough and the pitch of the coiled filament is short-circuited. When the pitch of coiled filaments is short-circuited, the resistance value of the filament decreases and the load increases, resulting in an overload exceeding the rating of the halogen lamp, causing overcurrent to flow through the lighting circuit, and the components that make up the lighting circuit Excessive stress will be added.

  Therefore, in this kind of lighting device and copying machine, a thermal protector is provided in the lighting circuit, and when the temperature of the lighting circuit or the halogen lamp exceeds a predetermined set temperature, a device that cuts off the power supply to the halogen lamp is proposed. (For example, see Patent Document 2).

JP-A-63-250091 JP 59-156968 A

  By the way, in the above-mentioned thermal protector, there are a return type that supplies power to the halogen lamp again when the temperature is lowered by shutting off the power supply to the halogen lamp, and a non-return type that does not supply power even if the temperature is lowered. . In the above-described lighting apparatus and copying apparatus, a resettable thermal protector is often used because of its convenience and manufacturing cost.

  However, when a resettable thermal protector is used, the apparatus can be used for a predetermined period without replacing the halogen lamp, and the replacement time of the halogen lamp tends to be delayed. When the overloaded halogen lamp is not replaced, an overcurrent flows through the lighting circuit, and there is a problem that an excessive load is applied to the lighting circuit and the life of the device itself is shortened.

  The present invention has been made in view of the above-mentioned freedom, and the object of the present invention is to reduce the excessive load applied to the lighting circuit at the end of the life of the halogen lamp, thereby extending the life of the device. It is to provide a lighting device that can be used.

  In order to achieve the above object, in the lighting device of the present application, the halogen lamp is configured to supply the lighting power to the halogen lamp, the end-of-life detection means for detecting the end-of-life condition of the halogen lamp, and the end-of-life detection means. When it is detected that the terminal state is in an end state, it is provided with a disconnection means for supplying a current necessary for disconnecting the filament of the halogen lamp from the lighting means to the halogen lamp.

  Further, the lighting device of the present application includes a lighting means for supplying lighting power to the halogen lamp, a life end detection means for detecting the end of life state of the halogen lamp, and a life end detection means that the halogen lamp is in the end of life state. When detected, the lighting power supplied from the lighting means to the halogen lamp is reduced below the rated value.

  In the lighting device described above, it is preferable to provide notification means for notifying that the lamp life of the halogen lamp has elapsed based on the output from the life detection means.

  According to the lighting device of the present application, it is possible to reduce the excessive load applied to the lighting circuit at the end of the life of the halogen lamp, thereby extending the life of the device.

It is a schematic circuit diagram which shows the lighting device concerning Embodiment 1 of this application. (A), (b) is a schematic circuit diagram which shows an example of the lighting circuit, the end-of-life detection circuit, and current application circuit which comprise the lighting device. It is the schematic for demonstrating the arrangement method of the thermal protector in the lighting device. It is a schematic circuit diagram which shows the lighting device concerning Embodiment 2 of this application. It is a schematic circuit diagram which shows an example of the lighting circuit which comprises the lighting device.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
The lighting device 1 according to the present embodiment will be described with reference to FIGS. As shown in FIG. 1, the lighting device 1 according to the present embodiment includes a lighting circuit 10 to which a halogen lamp 2 serving as a light source is connected and power is supplied from a commercial power source AC to supply lighting power to the halogen lamp 2. Prepare. The lighting circuit 10 includes a life detection circuit 11 for detecting the end of life of the halogen lamp 2 and a current necessary for breaking the filament (not shown) of the halogen lamp 2 when the life detection circuit 11 detects the end of life. A current application circuit 12 that flows through the halogen lamp 2 is connected.

  The lighting circuit 10 has a soft start function, reduces the inrush current to the halogen lamp 2 at the start of lighting, and reduces the load on the filament of the halogen lamp 2. In addition, the lighting circuit 10 detects overheating / overcurrent of the halogen lamp 2 or the lighting circuit 10 in order to suppress the overcurrent from flowing to the halogen lamp 2 or the lighting circuit 10, and stops the power supply to the halogen lamp 2. It has a function to make it.

  The life detection circuit 11 detects whether or not the halogen lamp 2 is in an end-of-life state based on the cumulative lighting time of the halogen lamp 2, the current value of the current flowing through the halogen lamp 2, and the like. When it is determined that the halogen lamp 2 is at the end of its life, the life detection circuit 11 outputs a detection signal indicating that to the current application circuit 12. The current application circuit 12 operates so that a current sufficient to break the filament of the halogen lamp 2 flows through the halogen lamp 2 in response to the detection signal.

  Accordingly, when the halogen lamp 2 reaches the end of its life, for example, when the shape of the filament is rough and the pitch between the filaments is short-circuited, an excessive current is supplied for a short time by the current application circuit 12. it can. As a result, it is possible to reduce an excessive load applied to the lighting circuit 10 a plurality of times, thereby extending the life of the lighting device 1 and prompting the user to replace the halogen lamp 2.

  Here, a specific electric circuit of each circuit (the lighting circuit 10, the life detection circuit 11, and the current application circuit 12) will be described with reference to FIGS. 2 (a) and 2 (b).

  The lighting circuit 10 is a self-excited lighting circuit as shown in FIG. 2A, and the AC input terminal of the full-wave rectification diode bridge DB1 is connected to the commercial AC power supply AC via the line filter choke LF1. ing. A surge absorber AV1, a filter capacitor C1, and a fuse F1 are connected to the front stage of the line filter choke LF1. A series circuit of capacitors C2 and C3 and a series circuit of transistors Q1 and Q2 are connected in parallel on the DC output terminal side of the diode bridge DB1, and a halogen is connected between connection points of each series circuit via an output transformer T1. The lamp 2 is connected (see FIG. 2 (b)). Note that one end of the primary winding and the secondary winding of the output transformer T1 are connected to each other via capacitors C7 and C8.

  The lighting circuit 10 includes a starter circuit 13 and a self-excited oscillation control circuit 14 as its constituent elements. The starting circuit 13 includes resistors R3, R5, and R6, capacitors C4 and C9, a voltage response element Q3, and a diode D2, and is set so that the transistor Q2 is turned on immediately after the power is turned on.

  The self-excited oscillation control circuit 14 includes a current transformer CT1, resistors R1, R2, and R4, capacitors C5 and C6, and a diode D1. When the transistor Q2 is set to an on state by the activation circuit 13, the transistors Q1 and Q2 Is self-oscillated.

  The current transformer CT1 is for current feedback, and is provided between the connection point of the transistors Q1 and Q2 and the primary winding side of the output transformer T1. One end of each of the pair of secondary windings provided in the current transformer CT1 is connected to the emitter side of the transistors Q1 and Q2, and the other end is connected to the base side of the transistors Q1 and Q2 via the base resistors R1 and R2. It is connected. The pair of secondary windings provided in the current transformer CT1 are wound so as to have opposite polarities, and operate to alternately turn on / off the transistors Q1 and Q2.

  When the lighting circuit 10 is powered on, charging of the capacitor C9 is started. When the charging voltage reaches the breakover voltage of the voltage response element Q3, the voltage response element Q3 is turned on. As a result, the charge of the capacitor C9 flows between the base and emitter of the transistor Q2, so that the transistor Q2 is turned on. When the transistor Q2 is turned on, a current flows through the path of the diode bridge DB1, the capacitor C3, the output transformer T1, the current transformer CT1, the transistor Q2, and the diode bridge DB1. At this time, the current is fed back by the current transformer CT1, and the transistor Q2 is biased in the ON state and the transistor Q1 is biased in the OFF state.

  Thereafter, when the current flowing to the primary winding side of the current transformer CT1 increases and reaches a predetermined limit value, the direction of the electromotive force of the secondary winding of the current transformer CT1 is reversed, and the transistor Q1 is turned on. Q2 is biased in the direction of turning off.

  Thereby, the self-excited oscillation operation in which the transistors Q1 and Q2 are alternately turned on / off at a predetermined cycle is continued, and high-frequency lighting power set to a predetermined voltage value (for example, AC12V) is supplied to the halogen lamp 2. The halogen lamp 2 is turned on. After the lighting circuit 10 starts the self-oscillation operation, when the transistor Q2 is turned on, the charge of the capacitor C9 is discharged through the diode D1, and the starter circuit 13 stops its operation. .

  FIG. 2B shows a life detection circuit 11 and an application circuit 12 connected to the halogen lamp 2, and includes a transistor Q4, a DC power source DC1, resistors Rx, Ry, Rz, and a thermal protector TP. As prepared. A DC power source Vcc set to a predetermined voltage value is connected to the resistor Rz.

  The direct current power source DC1 is connected between both ends of the halogen lamp 2 via the transistor Q4, and is set so that the current from the direct current power source DC1 flows to the halogen lamp 2 when the transistor Q4 is turned on. In the DC power source DC1, the current value flowing through the halogen lamp 2 is set to a current value that can cut the filament of the halogen lamp 2.

  The thermal protector TP is disposed in the vicinity of the transistor Q1 or the transistor Q2. In this embodiment, as shown in FIG. 3, it is arranged in the vicinity of the transistor Q2, the value of the current flowing through the transistor Q2 increases, and the thermal protector TP is turned off when the transistor Q2 becomes higher than a predetermined temperature. Become.

  Here, the DC power source Vcc is divided by the resistance ratio of the combined resistance of the resistors Rx and Ry and the resistor Rz when the thermal protector TP is on, and the resistor Ry when the thermal protector TP is off. And the resistance Rz. Accordingly, the resistance values of the resistors Rx, Ry, and Rz are such that the transistor Q4 is turned on when the thermal protector TP is off, and the transistor Q4 is turned off when the thermal protector TP is on. Is set to Therefore, when the thermal protector TP is turned off, the transistor Q4 is turned on based on the resistance ratio of the resistors Ry and Rz, and power is supplied to the halogen lamp 2 from the DC power source DC1. As a result, a current sufficient to break the filament flows in the halogen lamp 2, and the filament breaks.

  That is, when the halogen lamp 2 reaches the end of life state, an overcurrent flows through the transistors Q1 and Q2 of the lighting circuit 10 and the temperature rises. The thermal protector TP detects this temperature rise, whereby the filament of the halogen lamp 2 is Disconnected. Thereafter, the lighting circuit 10 stops operating, and even if the temperature of the thermal protector TP decreases and returns, the lighting circuit 10 is not driven again because the filament of the halogen lamp 2 is disconnected. Accordingly, it is possible to reduce the frequency of overcurrent flowing through the lighting circuit 10 as in the conventional case, and even when the halogen lamp 2 is in the end of life state, the lighting circuit 10 is reduced from being overloaded and turned on. The life of the device 1 can be extended.

  In this embodiment, the lighting circuit 10 is a self-excited lighting circuit, but may be a separately excited lighting circuit. Further, as the end-of-life detection circuit 11, a thermal protector TP is used to detect the end-of-life of the halogen lamp 2 based on the overcurrent flowing through the lighting circuit 10. It may be.

(Embodiment 2)
The lighting device 3 according to the present embodiment will be described with reference to FIGS. As shown in FIG. 4, the lighting device 3 according to the present embodiment includes a lighting circuit 20, a life detection circuit 21, and an output reduction circuit 22 as its constituent elements. The lighting circuit 20 is a lighting circuit for supplying lighting power to the connected halogen lamp 2, similarly to the lighting circuit 10 of the first embodiment. Similarly to the life detection circuit 11 of the first embodiment, the life detection circuit 21 detects whether or not the halogen lamp 2 is in the end-of-life state. A detection signal indicating that is output. In response to this detection signal, the output reduction circuit 22 controls the lighting circuit 20 so that the lighting power supplied from the lighting circuit 20 to the halogen lamp 2 is lower than the rated power of the halogen lamp 2. Thereby, even if the halogen lamp 2 is in the end-of-life state, it is possible to reduce overcurrent from flowing through the lighting circuit 10.

  Here, the specific electric circuit of each circuit (the lighting circuit 20, the life detection circuit 21, and the current application circuit 22) will be described with reference to FIG. The lighting circuit 20 is a separately-excited lighting circuit as shown in FIG. 5, and the drive controller IC1 continuously switches on / off the transistors Q5 and Q6 to drive the output transformer T1, Supply high-frequency lighting power.

  Further, a resistor R7 for measuring the value of the current flowing through the transistor Q5 is connected, and the voltage across the resistor R7 is received by the capacitor C0 and fed back to the controller IC1. Based on this feedback input, the controller IC1 changes the frequency at which the transistors Q5 and Q6 are switched on / off. Specifically, when the current flowing through the transistor Q5 increases and the feedback input becomes larger than a predetermined threshold value, the lighting power supplied to the halogen lamp 2 is controlled to be smaller than the rated power of the halogen lamp 2. Yes. Thereby, even if the halogen lamp 2 is in the end of life state, it is possible to reduce an excessive load on the halogen lamp 2 and the lighting circuit 10. Further, since the current continues to flow through the halogen lamp 2, the filament of the halogen lamp 2 is finally disconnected. Therefore, the filament of the halogen lamp 2 can be disconnected without imposing an excessive load on the lighting circuit 10, and the life of the lighting device 3 can be extended.

  In the first and second embodiments described above, when an indicator lamp such as a light emitting diode is connected to the life detection circuits 10 and 20, and the halogen lamp 2 is in the end of life state, the indicator lamp is turned on. You may make it let it. In this case, the user can know that the halogen lamp 2 is in an end-of-life state by turning on the indicator lamp, and expect the halogen lamp 2 to be replaced at an early stage.

DESCRIPTION OF SYMBOLS 1 Lighting device 2 Halogen lamp 10 Lighting circuit (lighting means)
11 Life detection circuit (End of life detection means)
12 Current application circuit (disconnection means)

Claims (3)

  A lighting means for supplying lighting power to the halogen lamp, an end-of-life detection means for detecting an end-of-life state of the halogen lamp, and when the end-of-life detection means detects that the halogen lamp is in an end-of-life state, the halogen lamp And a disconnecting means for supplying a current necessary for disconnecting the filament from the lighting means to the halogen lamp.   Lighting means for supplying lighting power to the halogen lamp, end-of-life detection means for detecting the end-of-life state of the halogen lamp, and when the end-of-life detection means detects that the halogen lamp is in the end-of-life state, the lighting A lighting device characterized in that lighting power supplied from the means to the halogen lamp is reduced below a rated value.   3. The lighting device according to claim 1, further comprising a notification unit configured to notify that a lamp life of the halogen lamp has elapsed based on an output from the life detection unit.

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