JP2003151786A - Lighting circuit of electric discharge lamp, light source device using lighting circuit, lighting circuit of optical device electric discharge lamp provided with light source device, light source device using lighting circuit of optical device electric discharge lamp, and optical apparatus provided with light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a lighting method of an electric discharge lamp which can prevent roughness of a surface of an electric discharge lamp electrode which occurs during DC/AC lighting and causes flicker, and prevent gradual reduction of luminance which occurs because deposit attributable to a halogen cycle is accumulated to tips of electrodes and a distance between the electrodes decreases. SOLUTION: During lighting of a DC electric discharge lamp 3a, an operating current in which a pulse current P is superposed at a constant interval to a DC current successively supplied to the DC electric discharge lamp 3a is applied to the DC electric discharge lamp 3a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of lighting a discharge lamp, a circuit thereof, a light source device using the circuit, and an optical apparatus equipped with the light source device.

[0002]

2. Description of the Related Art A DC discharge lamp lighting circuit is basically shown in FIG.
As shown in, the discharge lamp (103), which is composed of a DC ballast (101) and an igniter (102), is turned on. DC ballast (101)
Detects the lighting current of the discharge lamp (103) as a sense voltage (sense voltage of the sense resistor (107) = lighting current x sense resistance value) with the sense resistor (107) and senses with the sense resistor (107). In response to the pulse width signal output from the pulse width control circuit (108) corresponding to the voltage, the FET switching unit (1
04) is operated for switching, the lighting current output from the FET switching unit (104) is pulse-width controlled by this, and then this switching pulse current is smoothed by the smoothing capacitor unit (105) and necessary for lighting the discharge lamp. Electricity
(Lighting current x lighting voltage) is stably supplied to the discharge lamp (103).

The igniter (102) has its output transformer (106).
Are connected in series to the output circuit of the ballast (101),
It has a function of superimposing on the output of the ballast (101) at the time of starting (103) and supplying a high-voltage pulse to the discharge lamp (103) to start the discharge lamp (103).

After starting the discharge lamp (103), the electrodes of the discharge lamp (103)
Since the voltage between (E1) and (E2) decreases, the trigger circuit (10T) stops and the igniter (102) stops its operation. Thereafter, the discharge lamp (103) is applied with a direct current voltage determined by the operation of the discharge lamp (103) and a current controlled by the ballast (101) and is lit with a constant power (see FIGS. 1 and 24).

Although the discharge lamp (103) continues to light in this state, a large lighting current continuously flows through the electrodes (E1) and (E2) of the discharge lamp (103). The surface of the electrodes (E1) (E2), which was initially smooth as shown in 2, gradually became rough as the lighting time became longer, and the protrusions (e1) (e2) were formed on the surfaces of the electrodes (E1) (E2). ... occurs frequently (see FIG. 3). Then, the starting point movement in which the starting point of the discharge (F) moves from the place (e1) (e2) where the discharge is currently being made to another protrusion (e3) or (e4) is likely to occur. When the starting point movement occurs, it means that the state of the light source has changed, and flicker (shaking or fluctuation of the screen) occurs in the optical device using the discharge lamp (103) as the light source.

As another problem, the discharge lamp electrodes (E1) (E2)
Precipitates due to the halogen cycle may accumulate on the surface of the electrode, causing the distance (L) between the electrodes (E1) and (E2) to become narrower than the initial state, and the discharge lamp (103) continues to light. Lighting voltage gradually decreases. When the lighting voltage decreases, a larger current needs to be supplied from the ballast (101) in order to maintain constant power, and heat generation of the ballast (101) increases. In general, the ballast (101) is equipped with a circuit that limits the current as a protection circuit, so if the limit value of the supply current is exceeded, constant power cannot be maintained and the discharge lamp (1
The output to 03) decreases. As a result, it becomes impossible to maintain the required brightness in an optical device using the discharge lamp (103) as a light source.

The same applies to the AC discharge lamp lighting circuit shown in FIG. 25. The AC ballast (201) and the igniter (20
It is composed of 2) and turns on the discharge lamp (203). AC ballast
(201) detects the lighting current of the discharge lamp (203) as the lighting voltage with the sense resistor (207) (previously mentioned), and similarly with the above, the FET switching unit (204) controls the pulse width, and further the FET
The switching pulse current output from the switching unit (204) is smoothed by the smoothing capacitor unit (205) and converted to AC by the full bridge circuit (20F) to stably discharge the power required for lighting the discharge lamp. It is designed to supply to the electric lamp (203) (see FIG. 26).

In such a conventional AC discharge lamp lighting circuit, the AC current is controlled according to the lighting voltage, and the discharge lamp is driven at a constant power.
The method of lighting the (203) is used, but the discharge lamp (203)
As in the case of direct current lighting, the surface of the discharge lamp electrode (E1) (E2) becomes rough and the electrode surface (E1) (E2) is raised.
(e1) and (e2) occur, which makes it easier for the discharge (F) to move to the starting point, causing flicker (shaking or fluctuation of the screen) in optical equipment that uses this as the light source. It becomes an obstacle to the operation. Furthermore, as in the case of DC lighting, there is also the accumulation of precipitates due to the halogen cycle, and the discharge lamp (20
There is a decrease in brightness due to a decrease in output to 3).

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above conventional problems and is caused by the surface roughness of the discharge lamp electrode and the halogen cycle which occur during DC / AC lighting and cause flicker. Method of lighting a discharge lamp and a circuit thereof and a light source device using the circuit, which can eliminate the cause of gradually reducing the inter-electrode distance by gradually depositing a deposit that deposits on the tips of the electrodes. Another object is to develop an optical device equipped with the light source device.

[0010]

The method of lighting a discharge lamp according to the present invention (FIGS. 4 and 5) described in "Claim 1" is based on the basic concept of the present invention for solving the flicker problem. While operating the discharge lamp (3a), apply an operating current to the discharge lamp (3a) in which a pulse current (P) is superimposed on the DC current continuously supplied to the DC discharge lamp (3a) at regular intervals. "To do".

That is, in addition to the conventional method of maintaining a constant power by supplying a constant supply DC current to the DC discharge lamp (3a) at the time of steady lighting by the DC ballast (1a), a constant supply DC is intermittently provided at regular intervals. It is characterized in that the pulse current (P) is superimposed on the current. As described above, since a large current continues to flow through the electrodes (Ea1) (Ea2) of the discharge lamp (3a), the surface of the electrodes (E1) (E2) that was initially smooth as shown in FIG. However, as the lighting time becomes longer, it gradually becomes rough as shown in Fig. 3,
Many protrusions (e1) (e2) ... Are generated on the surfaces of the electrodes (E1) (E2).
The protrusions (e1) (e2) ... Often serve as discharge starting points, and as the number of the protrusions (e1) (e2) increases, the discharge starting point easily moves. This is considered to be the cause of flicker.

Therefore, it has become possible to suppress the movement of the discharge starting point by superimposing the pulse current (P) at regular intervals. It is considered that when the discharge starting point moves to another position, the current discharge point is fixed again as the most effective electron emission position due to the instantaneous pulse energy. That is, the fluctuation of the discharge point is suppressed or the discharge point is fixed.
Further, the electrodes (E1) and (E2) are instantaneously further heated by the superposition of the pulse current (P), and the protrusions (e1) (e2) on the surface of the electrodes (E1) (E2) ...
It is conceivable that the surface layers of the electrodes (E1) (E2) may be microscopically melted at the initial stage of the occurrence of the ridges to eliminate the protrusions (e1) (e2). As a result, the starting point movement is mainly fixed, and additionally, the protrusions (e1) (e2) ... Of the surface of the electrodes (E1) (E2), which cause the starting point movement, are suppressed from occurring and flicker-free and stable. The generated discharge (F) can be maintained for a long time.
Figure 5 shows the DC current waveform of the operating current with the pulse current (P) superimposed. Optimal values are set for the pulse width, pulse height, and pulse frequency of the superimposed pulse current (P) according to the discharge lamp (3a) applied in the method described later.

The method of lighting a discharge lamp (3b) according to the present invention as defined in claim 2 is a means for solving the above problems in an AC ballast (1b). Operation of superimposing a pulse current (P) of a certain width at the same time as the half cycle of the alternating current continuously supplied to the discharge lamp (3b) or at a position delayed by a certain time from the rising while the The current is supplied to the discharge lamp (3b) ”.

In the case of alternating current lighting, as in the case of direct current lighting, by superimposing a pulse current (P) at regular intervals, the same as above.
When the discharge starting point moves to another position, it is considered that the current discharge point is fixed again as the most influential point as the electron emission position due to the instantaneous pulse energy. Then, the protrusions (e1) on the surface of the electrodes (E1) (E2)
It is considered that (e2) ... may be microscopically melted by the pulse current (P) at the initial stage of its generation, and the protrusions (e1) (e2)
This prevents the occurrence of ..., As a result, the starting point movement is mainly fixed, and additionally the protruding points (e1) (e2) on the surface of the electrodes (E1) (E2) that cause the starting point movement ... It is possible to maintain stable discharge with no occurrence of flicker and no flicker. Fig. 8 shows the AC current waveform with the pulse current (P) superimposed. Optimal values are set for the pulse width and pulse height of the superimposed pulse current (P) according to the electrodes of different types of discharge lamps (3b) by the method described later. It is desirable that the timing of superimposing the pulse current (P) be off the falling edge of the half cycle.

"Claim 3" is an improvement of the method of lighting any one of the discharge lamps (3a) (3b) according to "Claim 1 or 2", "The lighting voltage drops below a certain value during steady lighting. In that case, the height of the superposed pulse current (P) is changed to a high value '', so that the movement of the starting point is mainly fixed, and the electrodes (E1) and (E2) are considered to be additionally generated. In addition to eliminating surface protrusions (e1) (e2) ..., narrowing the interelectrode distance (L) due to deposition of precipitates (S) on the surfaces of electrodes (E1) (E2) due to the halogen cycle It is possible to prevent a decrease in lighting voltage based on the above. That is, when the lighting voltage drops below a certain value during steady lighting, in addition to the operation of claim 1 or 2, the pulse current (P
a) is superimposed and the pulse (Pa) with a high pulse height is used to melt the precipitate (S) on the electrode surface, especially the precipitate (S) deposited on the tip of the electrodes (E1) (E2) to dissolve the electrode (E1 ) (E2) prevent the distance (L) from narrowing. As a result, it is possible to prevent the lighting voltage from falling below a certain value during steady lighting, and to maintain a stable discharge (F).

"Claim 4" is another improvement method of "Claim 3""When the lighting voltage drops below a certain value during steady lighting, the width of the superimposed pulse current (Pb) is changed widely". It is characterized in that the pulse height is constant and the pulse current (Pb) is made wider by further widening the pulse width by one step to heat the electrodes (E1) (E2) for a longer period of time to generate mainly. By fixing the movement of the starting point, the precipitates (S) are melted together with the surface protrusions (e1) (e2), which are considered to be additionally generated, to prevent the inter-electrode distance (L) from narrowing. is there.
As a result, it is possible to prevent the lighting voltage from dropping below a certain value and maintain stable discharge. Claims 3 and 4 can be applied to both direct current and alternating current.

"Claim 5" is a lighting circuit (FIG. 4) for realizing the DC lighting method of the discharge lamp (3a) according to "Claim 1".
, `` A DC ballast (1a) for supplying constant power to the DC discharge lamp (3a) by the pulse width control circuit (8a), and the DC ballast (1a)
a) connected in series to the DC discharge lamp (3a) for applying a starting voltage to the igniter (2a), and connected to the pulse width control circuit (8a) of the DC ballast (1a), and the DC ballast generated by the pulse generation. And a pulse generation circuit (9a) for superposing a pulse current (P) on the output current of (1a) ”.

"Claim 6" is a circuit for realizing the AC lighting method of the discharge lamp (3b) described in "Claim 2" (Fig. 7).
, `` The AC ballast (1b) for supplying constant power to the AC discharge lamp (3b) by the pulse width control circuit (8b) and the AC ballast (1
An igniter (2b) that is connected in series to b) and applies a starting voltage to the AC discharge lamp (3b), and is connected to the pulse width control circuit (8b) of the AC ballast (1b), and an AC ballast (1b). Pulse current (P) is generated at the same timing as when the AC current waveform is switched or at a certain time later than that, and at the same time as or during the rising of a half cycle of the AC current continuously supplied to the discharge lamp (3b). And a pulse generation circuit (9b) that superimposes the pulse current (P) having a constant width at a position delayed by a predetermined time.

"Claim 7" is a voltage maintaining circuit (30a) (3) which realizes the method of "Claim 3" (increasing the pulse height).
0b) is added to the circuit (Figs. 11 and 14), "In the pulse generation circuit (9a) (9b) of the lighting circuit of the discharge lamp (3a) (3b) of claim 5 or 6, (3a) (3b) lighting current is detected as a sense voltage by the sense resistor (7a) (7b), if the sense voltage is less than the set value during steady lighting, the pulse current (Pa) to be superimposed is high. The pulse high voltage maintaining circuits (30a) and (30b) are connected to the pulse width control circuits (8a) and (8b) ”.

The "claim 8" is a voltage maintaining circuit (40a) (40) for realizing the method of claim 4 (widening the pulse width).
In the circuit (FIGS. 17 and 19) with the addition of b), "In the pulse generating circuit (9a) (9b) of the lighting circuit of the discharge lamp (3a) (3b) of claims 5 to 7, (3a) (3b) lighting current is detected as a sense voltage by the sense resistor (7a) (7b), if the sense voltage is less than or equal to the set value during steady lighting, the width of the pulse current (Pb) to be superimposed Is connected to the pulse width control circuits (8a) and (8b) ”.

"Claim 9" relates to a light source device using the "discharge lamp lighting circuit according to claims 5 to 8," wherein "the discharge lamp lighting circuit according to claims 5 to 8 and the center of the concave reflection surface portion (r1) are provided. A reflector (R) provided with a discharge lamp mounting part (r2) and a discharge lamp in which the seal part (m) is mounted on the discharge lamp mounting part (r2).
(3a) (3b) ", and" claim 1
The optical device of "0" is composed of "the light source device according to claim 9 and an optical system for irradiating the screen in front with light from the discharge lamps (3a) (3b) mounted on the light source device". And

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to Examples. Example 1 [FIGS. 4 to 6] is a DC discharge lamp lighting circuit including a pulse generation circuit (9a) for preventing flicker. The ballast (1a) is for DC, and the ballast (1a) is connected in series with the igniter (2a).
The discharge lamp (3a) for DC is connected to a).

The DC ballast (1a) is connected to a DC power source (Da) and a ground side between a pair of smoothing capacitors (5a) described later, and a sense resistor (7a) for detecting a lighting current and the sense resistor ( 7a) detects the lighting current of the discharge lamp (3a) as a sense voltage and controls the switching unit (4a) described below based on this sense voltage to supply the pulse current to the current supplied from the DC power supply (Da). A pulse width control circuit (8a) for controlling, a switching unit (4a) for performing pulse width control of the current supplied from the DC power supply (Da) by performing a switching operation according to a control signal from the pulse width control circuit (8a). ), Is connected to a pair of smoothing capacitors (5a) and a pulse width control circuit (8a) for smoothing the switching waveform output from the switching unit (4a), and superimposes the pulse current (P) on the steady supply DC current. It is composed of a pulse generation circuit (9a).

The pulse width control circuit (8a) includes a sense resistor
The voltage signal based on the discharge lamp current signal from (7a) and the pulse signal from the DC pulse generation circuit (9a) are input, and pulse width control is performed in a form that combines them, and the result is supplied to the discharge lamp (3). As the current, an operating current having a waveform in which a pulse current (P) is superimposed as shown in FIG. 5 is output.

FIG. 6 shows the details of the DC pulse generating circuit (9a). The DC pulse generator circuit (9a) is
0a), an amplifier (11a) for amplifying the lighting current signal, a voltage dividing circuit (12a) having a function to be described later, and a pulse oscillation circuit (10a) are connected to divide the pulse signal from the pulse oscillation circuit (10a). It is composed of a transistor (13a) to be added to the voltage circuit (12a). The pulse oscillating circuit (10a) is a circuit that oscillates a rectangular wave, and its oscillating waveform is a waveform in which the pulse generation time is short and the pulse interval is long and the duty is different. The pulse oscillator circuit (10a) has a variable resistor (14
a), a variable resistor (15a) that determines the pulse interval is provided, and a variable resistor (16a) that determines the pulse height is provided in the collector of the transistor (13a) in the next stage, and each is separately provided. The pulse width, pulse interval, and pulse height of the pulse current (P), which is the adjustment, can be freely changed. The emitter of the transistor (13a) is connected to ground (17a).

The current signal amplification amplifier (11a) is an amplifier for raising the lighting current signal to a level at which a voltage dividing process described later can be performed. Voltage dividing circuit (12a) connected in series between the current signal amplification amplifier (11a) and the pulse width control circuit (8a)
Is a resistor (121a) (123a) (123a) connected in series on both sides of the connection point (C1).
a), a variable resistor (16a) for determining the aforementioned pulse height connected between the collector of the transistor (13a) whose collector side is connected to the earth (17) and the connection point (C1),
It is composed of a voltage dividing resistor (122a) connected between the output side connection point (C3) of the resistor (123a) and the ground (17a ').

When the lighting operation of the DC discharge lamp (3a) is performed, a high voltage is required before lighting, and therefore the igniter (2a) is activated at the time of starting to apply the high voltage to the DC discharge lamp (3a). .
After lighting, the voltage drops, the igniter (2a) stops, the lighting state becomes steady, and the voltage gradually rises. This also applies to the AC discharge lamp (3b) described later. In the steady lighting state, as described above, the surfaces of the electrodes (E1) and (E2) gradually become rough, and the protrusions (e1) (e2) ... Occur. In the circuit of the first embodiment, during steady lighting, the pulse generator (9a) operates to superimpose a pulse current (P) having an optimum pulse width, pulse interval, and pulse height on the supplied DC current at regular intervals to generate DC. When the discharge starting point is supplied to the discharge lamp (3a) and the starting point of the discharge tries to move to another position, the current discharge point is fixed again as the most influential point as the electron emission position due to the instantaneous pulse energy. Then, a phenomenon that is considered to occur additionally, that is, the surface of the electrodes (E1) (E2) is pulsed with current (P)
Is microscopically melted to eliminate the roughness of the electrode surface.

That is, when the pulse oscillating circuit (10a) of the pulse generating circuit (9a) generates a pulse, the transistor (13a) performs a switching operation according to the pulse, and the variable resistor of the voltage dividing circuit (12a) is operated for the pulse generating time. Connect (16a) to ground (17a). As a result, the lighting current signal amplified by the current signal amplification amplifier (11a) is shunted at the connection point (C1), and the resistance (123a) (1
22a) and the variable resistor (16a) to generate voltage values according to the resistance values of the resistor (122a) and the variable resistor (16a), respectively.
The voltage of (122a) is applied to the pulse width control circuit (8a).

Now, the lighting current signal flowing through the resistor (121a) is
(i0), the current flowing through the resistor (122a) is (i1), the resistor (16a)
The current flowing through is (i2), and the resistance value of each is (R0) (R1)
Assuming that (R2), the transistor (13a) is off between the pulse (p0) and the pulse (p0) output from the pulse oscillation circuit (10a), so the current flowing through the resistor (122a) is ( i0)
And the voltage generated in the resistor (122a) becomes (i0). (R1). This voltage is equal to the voltage (standard voltage during steady lighting = (V)) based on the lighting current signal value before input to the amplifier (11), and the steady supply DC current of Fig. 5 (pulse current (P) is superimposed). (Nothing) Output from DC ballast (1a).

On the other hand, when the pulse (p0) is output from the pulse oscillation circuit (10a), the transistor (13a) is turned on during the pulse generation time, and the current (i) is supplied from the connection point (C1).
2) is branched and flows into the variable resistor (16a), a current (i1 = i0-i2) flows through the resistor (122a), and the voltage (i1
R1 <i0 · R1 or (V) decreases. As a result, the pulse width control circuit (8a) determines that the lamp current value has decreased, and increases the supply current by the amount of voltage decrease for the pulse output time.
This is superimposed on the steady supply DC current as a pulse current (P). The current (i1) (i2) flowing through each resistor (122a) (16a) is proportional to each resistance value (R1) (R2) .Therefore, by changing the resistance value of the variable resistor (16a), (122
The voltage generated in a) can be changed, and the amount of supply current at the pulse generation time by the pulse width control circuit (8a) can be changed, that is, the pulse height can be changed.

In this way, the amount of electric power (here, the amount of current) supplied to the DC discharge lamp (3a) is temporarily increased for the pulse generation time, and the current discharge point is changed to the discharge point by this instantaneous pulse energy. To fix as. At this time, the electrodes (E1) (E2) are rapidly heated by the pulse width to instantaneously melt the electrode surface, and the protrusions (e1) (e2) ... It may be microscopically smooth. As a result, the starting point movement is suppressed mainly by the pulse superposition, and the protrusions (e1) on the surface of the electrodes (E1) (E2), which are considered to be one of the causes of the starting point movement additionally generated.
(e2) ... is suppressed and stable discharge without flicker
(F) can be maintained for a long time. Figure 5 shows the DC current waveform with the pulse current (P) superimposed.

Second embodiment of the present invention (in the case of alternating current lighting)
Will be described. FIG. 7 shows an AC discharge lamp lighting circuit having a pulse generation circuit (9b) for preventing flicker according to this embodiment. The ballast (1b) is for AC, and the igniter (2b) is connected in series as in the case of DC, and the AC discharge lamp (3b) is connected to the igniter (2b).

The structure of the ballast (1b) is a full bridge circuit.
It is basically the same as for DC only with (F) added. The AC ballast (1b) is connected to the DC power supply (Db) and the negative side between the pair of smoothing capacitors (5b) described later,
A sense resistor (7b) for detecting a lighting current, the sensing resistor (7b) detects the lighting current of the discharge lamp (3b) as a sense voltage, and based on this sense voltage, a switching unit described below (4b Pulse width control circuit (8b) that controls the pulse width of the current supplied from the DC power supply (Db) by controlling
The switching section (4b) that performs switching operation according to the control signal from (8b) and controls the pulse width of the supply current from the DC power source (Db) as described above, and the switching waveform output from the switching section (4b) A pulse generator circuit (9b) that is connected to a pair of smoothing capacitors (5b) and a pulse width control circuit (8b) for smoothing, and that superimposes a pulse current on a steady supply DC current, to convert the smoothed DC current to AC. The full bridge circuit (F) and an AC pulse generation circuit (9b) for superimposing a pulse current on a steady supply AC current.

Pulse width control circuit (8b) as in the case of direct current
A voltage signal based on the discharge lamp current signal from the sense resistor (7) and a pulse signal from the AC timing control pulse generation circuit (9b) are connected as input signals to the. The AC pulse generation circuit (9b) receives a signal from the full bridge control circuit (F) and synchronizes with the full bridge circuit (F) during the inverting operation of the full bridge circuit (F) (the edge portion of the waveform) or this. Avoid it, and generate a pulse at the required timing in the flat part of the rectangular wave AC current waveform. That is, the pulse is generated at the same time as the rising of the supplied alternating current of the rectangular wave or with a slight delay from this.

As a result of the pulse width control circuit (8b) performing pulse width control in a combined form, the current supplied to the discharge lamp (3b) has a waveform in which the pulse current (P) is superimposed as shown in FIG. Become. That is, as described above, when a pulse current (P) is generated at the same time as the rising of the rectangular-wave AC supply current and is superimposed, a short-time pulse current (P) is generated at the rising portion of the rectangular-wave AC current as indicated by the broken line. ) Is observed, and when a slight delay time is provided in the pulse generation timing, the pulse current (P) indicated by the solid line is superimposed on the central portion of the flat portion of the rectangular wave AC current. However, due to the time constant of the delay circuit, the superposition of the pulse current (P) is not superposed on the latter half of the rectangular wave alternating current. FIG. 9 shows the details of the AC pulse generation circuit (9b).

The AC pulse generation circuit (9b) receives the full-bridge control signal from the full-bridge control circuit (F) and generates a pulse delayed by a certain time (t) from the time of switching the waveform (it may be simultaneous). Delay circuit (21b) for delaying
A trigger circuit (22b) that outputs a trigger signal by a signal input from (21b), a single pulse generation circuit (10b) that generates a pulse by the trigger signal from the trigger circuit (22b), and an amplifier that amplifies the lighting current signal (11b) Similarly to the above, when the pulse is not generated, the level of the amplified lighting current signal is returned to the original level before amplification and output to the pulse width control circuit (8b), and when the pulse is generated, the apparent lighting current signal value is output. A voltage dividing circuit (12b) that lowers and outputs to the pulse width control circuit (8b), the pulse signal from the single pulse generating circuit (10b) is added to the voltage dividing circuit (12b), and the apparent lighting when the pulse is generated. And a transistor (13b) for reducing the current signal value.

The single pulse generation circuit (10b) is a so-called one-shot multi-circuit, and has a resistor (1
4b) is provided, and a resistor (16b) for determining the pulse height is connected to the collector of the transistor (13b) at the next stage, and can be adjusted separately. When the pulse is generated at the same timing as when switching, the delay circuit (21b) is unnecessary.

The current signal amplification amplifier (11b) and the voltage dividing circuit (12
Since the configuration and operation of b) are the same as in the case of direct current (11a) (12a), the description thereof will be omitted by citing the case of direct current.

In the above case, when the pulse is generated with a delay of a fixed time (t) from the time of switching the waveform, the delay circuit (21b) receives the full bridge control signal from the full bridge control circuit (F), The ON / OFF operation is repeated when the set time (t) has elapsed since the bridge control signal was input. The trigger circuit (22b) turns on the delay circuit (21b).
The trigger signal is output to the single pulse generation circuit (10b) in synchronization with the OFF timing, and the single pulse generation circuit (10b) receives this and outputs the pulse signal. The width of the pulse signal can be adjusted with the pulse width setting variable resistor (14b) (Fig.
10).

When the pulse signal is output from the single pulse generation circuit (10b) to the transistor (13b) and the state between the pulse signals is the same as the case of direct current, the pulse generation circuit (9b)
When the single pulse oscillator circuit (10b) of generates a pulse, the transistor (13b) performs switching operation according to the pulse, and the variable resistor (16b) of the voltage dividing circuit (12b) is generated for the pulse generation time.
Is connected to the ground (17b) and the amplified lighting current signal is at the connection point.
It splits at (C1) and flows to the resistor (122b) and the variable resistor (16b).

Now, the lighting current signal flowing through the resistor (121b) is
(i0), the current flowing through the resistor (122b) is (i1), the resistor (16b)
The current flowing through is (i2), and the resistance value of each is (R0) (R1)
(R2), between the pulses output from the single pulse oscillator (10b), the resistance (1
Voltage (i0) ・ (R1) equal to the lighting current signal value (standard voltage during steady lighting) before being input to the amplifier (11) is generated at 22a) and is input to the pulse width control circuit (8b). As a result, the steady supply AC current (the portion where the pulse current (P) is not superimposed) is output from the AC ballast (1b).

On the other hand, when a pulse is output from the single pulse oscillator circuit (10b), the transistor (13b) is turned on during the pulse generation time, and the current (i) is supplied from the connection point (C1).
2) branches and flows into the variable resistor (16b), a current (i1 = i0−i2) flows in the resistor (122b), and the voltage (i1
R1 <i0 · R1 or (V) decreases. As a result, the pulse width control circuit (8b) determines that the lamp current value has decreased, and increases the supply current for the pulse output time from the single pulse oscillation circuit (10b). This is superposed on the steady supply alternating current as a pulse current (P). As in the case of DC, the pulse height can be changed by changing the resistance value of the variable resistor (16b). The timing of superimposing the pulse current (P) can be freely selected by operating the delay circuit (21b). When the delay circuit (21b) is omitted or the delay time (t) is set to 0, the pulse current (P) is superimposed on the steady supply AC current at the same timing as the switching timing of the full bridge control signal. Here, the falling portion of the rectangular steady supply AC current is avoided as the superposition timing of the pulse current (P).

In this way, as in the case of DC, the amount of electric power (here, the amount of current) supplied to the DC discharge lamp (3b) is temporarily increased for the pulse generation time, and this instantaneous pulse energy is used. The current discharge point is fixed as the discharge point. At this time, the electrodes (E1) (E2) are rapidly heated to melt the electrode surface, and the protrusions (e1) (e2) ... Generated on the electrode surface are microscopically melted to smooth the electrode surface. It is thought that this also happens additionally. As a result, similarly to the above, it is considered that the starting point movement is suppressed by the pulse superposition and that the additional starting point is caused, and the protrusions (e1) (e2) ... of the surface of the electrodes (E1) (E2) that cause the starting point movement. It is possible to maintain a stable discharge for a long time without generation of flicker with suppressed generation. Figure 10 shows the DC current waveform with the pulse current (P) superimposed.

Next, a third embodiment of the present invention will be described. FIG. 11 shows the pulse generator circuit (9a) of the first embodiment "see FIG. 6"
Voltage maintenance circuit (30a) to increase the pulse height
In addition to the pulse generation circuit (9a) for preventing flicker of [Example 1], the electrode (E
1) The voltage maintenance circuit to prevent the voltage drop of the discharge lamp (3a) due to the narrowing of the interelectrode distance (L) due to the deposition of precipitate (S) on the surface of (E2), especially on the tip part ( 30a) is added. The broken line portion (Pa) of the pulse current (P) in FIG. 13 is the pulse current of the pulse high voltage maintenance circuit (30a) of the third embodiment.
This is a part of the effect of raising the height of (P).

The pulse high voltage maintaining circuit (30a) includes an amplifier (11
Timer circuit (31a) connected to the output side of a), comparison circuit (32a) having a sustain voltage setting function (33a), pulse oscillation circuit
(10a) and the output of the comparison circuit (32a) to connect the resistor (34
a), the base is connected to the comparison circuit (32a), the collector is connected to the connection point (C2) of the voltage dividing circuit (12a) through the resistor (35a), and the emitter is ground (17a ''). And a transistor (36a) connected to.

When the DC discharge lamp (3a) is lit, as described above, the voltage is low initially and gradually rises with the passage of time, and then the DC discharge lamp (3a) is lit at a constant voltage determined by the DC discharge lamp (3a). This also applies to the AC discharge lamp (3b) described later. As an example, FIG. 22 shows the relationship between the output current of the DC ballast (1a) and the 200 W lighting voltage.

When the lighting voltage is within a certain range (steady lighting), the DC ballast (1a) controls the output current in order to maintain constant power. That is, the lighting voltage can be known from the output current of the DC ballast (1a). Pulse high voltage maintenance circuit (30
In a), the timer circuit (31a) is a timer to wait until the voltage becomes constant after lighting the discharge lamp.
~ N), the output voltage (n times the sense voltage) of the current signal amplifier (11a) is compared with the comparison circuit (32
tell a). The comparison circuit (32a) compares the output voltage (n times the sense voltage) based on the lighting current signal with the sustain voltage setting value (that is, the reference voltage) at that time, and outputs the current signal amplifier (11a) based on the current signal. Voltage is the maintenance voltage setting value (reference voltage)
If it exceeds, it means that the sense voltage is high, which means that the lighting current flowing through the sense resistor (7a) is increasing. Since the electric power supplied to the DC discharge lamp (3a) is controlled to be constant, an increase in lighting current means a decrease in lighting voltage.

That is, the current signal amplifier (11a) is supplied from the reference voltage.
It is determined that the lighting voltage has decreased when the output voltage of the device has increased (that is, the distance (L) between the electrodes has become narrower due to the precipitate (S)), and the transistor (36a) in the next stage can be turned on. The pulse oscillator circuit (10a) pulse (p0) as described below.
At the timing of transmission, turn on the transistor (36a),
A voltage dividing resistor (35a) is added to the voltage dividing circuit (12a). In addition, here, "the next stage transistor (36a) is the comparison circuit (32a)
It means that the base of the transistor (36a) is not connected to the ground (not shown) when the output voltage of the current signal amplifier (11a) is higher than the reference voltage. On the contrary, when the output voltage of the current signal amplifier (11a) is lower than the reference voltage, it means that the base of the transistor (36a) is connected to the ground (not shown). As a result, the resistance (3
When the pulse (p0) is applied to the base of the transistor (36a) through 4a), the transistor (36a) is activated in the former case and is not activated in the latter case.

This will be described in more detail. Voltage divider (12
Let (i0) be the amplified lighting current signal that flows through the resistor (121a) in a),
When the transistor (36a) is off, the current flowing through the resistor (122a) is (i1), the current flowing through the variable resistor (16a) is (i2),
When the transistor (36a) is on, the current flowing through the resistor (122a) is (i4), the current flowing through the variable resistor (16a) is (i5),
The current flowing through the resistor (35a) is (i3), and each resistance value is
(R0) (R1) (R2) (R3) Now, in the steady lighting state, the timer circuit (31a) operates and the comparison circuit (32a) starts the comparison operation. Pulse generator circuit (9a)
When (a) generates a pulse (p0), the transistor (13a) performs switching operation according to the pulse (p0), and the variable resistor (16a) of the voltage dividing circuit (12a) is connected to the earth (17a) for the pulse generation time. The pulse current (P)
Superimpose.

On the other hand, the amplified voltage of the lighting current signal is applied to one input terminal of the comparison circuit (32a) via the timer circuit (31a).
(n × sense voltage) is applied and compared with the reference voltage of the sustain voltage setting function (33a) connected to the other input terminal. The voltage (n) of the amplified lighting current signal input to the one input terminal from the reference voltage of the sustain voltage setting function (33a)
× sense voltage) is low, the lighting current is also small and therefore the lighting voltage is judged to be sufficiently high, and the comparison circuit (32a)
Connects the base of the transistor (36a) to ground, and the pulse (p0) output from the pulse oscillation circuit (10a) is the resistor (34a).
Even if it flows through to the base of the transistor (36a), it will be grounded and the transistor (36a) will remain off. As a result, the amplified lighting current signal (i
0) is shunted at the connection points (C1) (C3) to become currents (i1) (i2),
It flows through the variable resistor (16a) and the resistor (122a), and the pulse current (P) is superimposed on the steady supply DC current as in the case of the first embodiment. This fixes the discharge point and eliminates flicker. At this time, the electrodes (E1) and (E2) are intermittently heated and the protrusions (e1) (e1) (e1)
2)… It is also possible that intermittent melting disappears.

On the other hand, when the voltage (n × sense voltage) of the amplified lighting current signal input to the one input terminal is higher than the reference voltage of the sustain voltage setting function (33a), the lighting current is high. Therefore, it is determined that the lighting voltage is low, and the comparison circuit (32a) cuts off the base of the transistor (36a) from the ground to enable the transistor (36a) to be turned on. Pulses (p0) are transmitted from the pulse oscillation circuit (10a) at regular intervals.The pulse (p0) is applied to the base of the transistor (36a) via the resistor (34a), and only the pulse (p0) width is applied. Turn on the transistor (36a). When the transistor (36a) is turned on, a current (i3) flows from the connection point (C2) to the resistance (35a) in addition to the connection points (C1) and (C3), and the variable resistance (16a) and the resistance (122a) are Current (i1) (i2) is current (i4) (i5)
Fall to. As a result, the voltage [current (i4) ・
The resistance value (R1) <(i1) · (R1)] is applied to the pulse width control circuit (8a). As a result, the pulse width control circuit (8a) causes the switching circuit (4a) to superimpose a larger amount of electric power (current amount) than the above case in proportion to the further reduced voltage (i4) and (R1).
To control. Note that the transistors (13a) and (36a) are turned on at the same timing and for the same width, so that the addition shown by the broken line is added, and a higher pulse current (Pa) is superimposed on the steady supply DC current. Will be.

As described above, the pulse current for flicker prevention
In addition to (P), a pulse current (Pa) for melting the precipitate (S) on the electrode surface is further superimposed, and as a result, the protrusions (e1) (e2) ... The precipitate (S) also melts and spreads on the electrode surface, and the distance between electrodes (E1) and (E2) (L)
Spreads. When the distance (L) between the electrodes increases, the lighting voltage increases (that is, the lighting current decreases), which causes the timer circuit (3
Input to one input terminal of the comparison circuit (32a) through 1a),
When the lighting voltage becomes higher than the reference voltage of the sustain voltage setting function (33a), the comparison circuit (32a) causes the transistor (36a) to operate as described above.
Is turned off, the shunting of the current (i3) to the resistance (35a) is stopped, and the superposition of the pulse current increase (Pa) for melting the precipitate (S) on the electrodes (E1) and (E2) is stopped. , [Embodiment 1] Return to the operation of superimposing only the pulse (P) for flicker prevention.

Next, a fourth embodiment of the present invention will be described. FIG. 14 shows a pulse generation circuit of the fourth embodiment. My goal is
As in the case of [Example 3], the discharge points are fixed and the protrusions (e1) (e2) ... and the precipitates (e1) (e2) ... S)
The pulse height is changed to eliminate it. Figure 1
5 shows details of the pulse high voltage maintaining circuit (30b) of this embodiment. The configuration is a pulse high voltage maintaining circuit (30b) added to the second embodiment, and the pulse height changing action is the same as that of the direct current of the third embodiment. In addition to the pulse current (P) for flicker prevention, The pulse current (Pa) for melting the precipitate (S) on the electrode surface is further superimposed, and as a result, the precipitate (S) disappears at the same time that the protrusions (e1) (e2) ... Also melts and spreads on the electrode surface, and the inter-electrode distance (L) between the electrodes (E1) and (E2) expands.

When the distance (L) between the electrodes increases, the lighting voltage rises as described above, and this is input to one input terminal of the comparison circuit (32b) through the timer circuit (31b) to maintain the sustain voltage setting function ( When the lighting voltage becomes higher than the reference value of (33b), the comparison circuit (32b) turns off the transistor (36b), and the resistance (3
5b) to stop the shunt of the current (i3), to stop the superposition of the pulse current increase (Pa) for melting the precipitate (S) to the electrodes (E1) (E2), The operation returns to the operation of superimposing only the pulse (P) for flicker prevention, and the configuration and the function and effect thereof will be replaced with the description of the fourth embodiment with reference to the third embodiment. The superimposing timing of the pulse current (P) and its increment (Pa) is the same as in the second embodiment.
The description of Example 4 is incorporated and replaced with the description of Example 4.

Next, a fifth embodiment will be described. In this case, different from the third embodiment, the width of the superimposed pulse current (P) is expanded, and its waveform is shown in FIG. (Pb) shows the increment. FIG. 17 shows details of the pulse width voltage maintenance circuit (40b) of the fifth embodiment. In this case, as compared with the third embodiment of FIG. 12, a capacitor (14a) for changing the pulse width is used instead of the variable resistor (14a) provided for the pulse generating circuit (10a) for changing the pulse width. ') Is used, a resistor (35a) connected to the collector of the transistor (36a) and a resistor (34a) connecting the output of the pulse oscillation circuit (10a) and the comparison circuit (32a) are taken, Instead, a capacitor (14a ') for adjusting the pulse width and a pulse oscillation circuit (10a)
And a collector (35a ') between the transistor (36a) and the collector of the transistor (36a), except that the capacitor (35a') is connected. The description of the third embodiment is applied to the configuration of the matching portion.

Next, the operation of the fifth embodiment will be described.
When the discharge lamp (3a) is turned on and the steady state is reached, the timer circuit (31a) operates as described above, and the comparison operation of the comparison circuit (32a) starts. In this state, the resistance of the voltage divider circuit (12a) (12
The amplified lighting current signal flowing through (1a) is (i0), and the resistor (122a)
The current flowing through (i1) is the current flowing through the variable resistor (16a)
2) and the respective resistance values (R0) (R1) (R2). When the pulse oscillating circuit (10a) of the pulse generating circuit (9a) generates a pulse (p0), the transistor (13a) performs switching operation according to the pulse (p0), and the voltage dividing circuit (12a) only for the pulse generation time.
Connect the variable resistor (16a) of the
Superimpose (P) on the steady-state DC current.

On the other hand, the amplified voltage of the lighting current signal is applied to one input terminal of the comparison circuit (32a) via the timer circuit (31a).
(n × sense voltage) is applied and compared with the reference voltage ratio of the sustain voltage setting function (33a) connected to the other input terminal. Amplified voltage of the lighting current signal input to the one input terminal from the reference voltage of the sustain voltage setting function (33a)
When (n × sense voltage) is high (that is, the sense current is high), it is determined that the lighting voltage is low, and in this case, unlike the case described above, the comparison circuit (32a) includes the transistor (36a).
A voltage is applied to the base of a) to turn on the transistor (36a).

In this state, when pulses (p0) are transmitted from the pulse oscillation circuit (10a) at regular intervals, the transistor (13a)
When the transistor (36a) is on, the capacitors (14a ') and (35a') are connected in parallel, and the capacitance of the capacitor increases. Therefore, the width of the pulse (p0) oscillated from the pulse oscillating circuit (10a) is widened by the time corresponding to the increased capacitor capacity. As a result, the on time of the transistor (36a) becomes longer, and the time of the current (i1) flowing through the resistor (122a) becomes longer. In accordance with this energization time, the pulse current output time of the pulse width control circuit (8a) is also expanded, the addition (Pb) shown by the broken line is added, and the wider pulse current (Pb
b) will be superimposed.

As described above, the pulse current for flicker prevention
In addition to (P), a pulse current extension (Pb) for melting the precipitate (S) on the electrode surface is further superimposed, and as a result, the discharge point is mainly fixed and additionally generated on the electrode surface. Disappearance and precipitation of microscopic projections (e1) (e2)…
(S) also melts and spreads on the surface of the electrodes, causing an increase in the inter-electrode distance (L) between the electrodes (E1) and (E2). When the distance (L) between the electrodes increases, the lighting voltage rises, which is the timer circuit (31a).
Input to one of the input terminals of the comparator circuit (32a), and when the lighting voltage becomes higher than the set value of the sustain voltage setting function (33a), the output of the comparator circuit (32a) becomes 0 and the transistor (36a)
Turns off, charging and discharging of the condenser (35a ') also stops,
Stopping the superposition of the pulse current increase (Pb) for melting the precipitate (S) on the electrodes (E1) and (E2), and returning to the operation of superimposing only the flicker prevention pulse (P) in [Example 1]. . In this case, the pulse interval is governed by the resistance value of the pulse interval adjusting resistor (15a) provided in the pulse oscillation circuit (10a).

On the other hand, when the amplified voltage (n × sense voltage) of the lighting current signal input to the one input terminal is lower than the voltage of the sustain voltage setting function (33a) (= the sense current is low), the lighting voltage is Is determined to be high, the comparison circuit (32
Transistor (36a) is turned off by a), and transistor (36a) does not operate. Therefore, the capacitor (35a ') does not operate, therefore, only the capacitor (14a') connected to the pulse oscillation circuit (10a) operates, and the pulse current (pulse current ( P) will be superimposed on the steady-state DC current. This mainly fixes the discharge point. In addition, the electrodes (E1) (E
It is considered that the heating of 2) may cause intermittent melting and disappearance of the protrusions (e1) (e2) on the electrode surface that cause flicker.

Finally, the sixth embodiment will be briefly described. In this case, Example 4 is changed according to Example 5, and the difference in configuration from Example 4 is Example 4 in FIG.
In comparison with the single pulse generation circuit (10b) is provided with a capacitor (15b ') instead of the variable resistor (14b) for changing the pulse interval, the transistor (36a)
A resistor (34a) that connects between the resistor (35a) connected to the collector of the pulse oscillator circuit (10a) and the output of the comparison circuit (32a)
Instead, a capacitor (35b ') is connected between the capacitor (15b') for adjusting the pulse interval and the pulse oscillator circuit (10a) and the collector of the transistor (36b). They are the same except that they are different. The description of the fourth embodiment is cited for the configuration of the matching portion.

Next, the operation of the sixth embodiment will be described.
When the discharge lamp (3b) is turned on and the steady state is reached, the timer circuit (31b) operates as described above, and the comparison operation of the comparison circuit (32b) starts. In this state, the resistance of the voltage divider circuit (12) (121
The amplified lighting current signal flowing through b) is (i0), the current flowing through the resistor (122b) is (i1), and the current flowing through the variable resistor (16b) is (i2).
And the respective resistance values (R0) (R1) (R2). When the pulse oscillating circuit (10b) of the pulse generating circuit (9b) generates a pulse, the transistor (13b) performs switching operation according to the pulse, and the variable resistor of the voltage dividing circuit (12b) for the pulse generation time.
Connect (16b) to ground (17b).

Here, the amplification point voltage of the lamp current signal is applied to one input terminal of the comparison circuit (32b) through the timer circuit (31b).
(n × sense voltage) is applied and compared with the reference voltage of the sustain voltage setting function (33b) connected to the other input terminal. The amplified voltage (n of the lighting current signal input to the one input terminal from the reference voltage of the sustain voltage setting function (33b)
× sense voltage) is high (sense current is large),
It is determined that the lighting voltage is low, the transistor (36b) is turned on by the output from the comparison circuit (32b), and the capacitor (35b ') is charged and discharged.

As described above, in this case, the capacitor (35b ')
Is connected in parallel with the capacitor (15b ') of the pulse oscillator circuit (10b) and its capacity increases, so that the pulse width of the pulse (p0) output from the pulse oscillator circuit (10b) is expanded. Therefore, the on-time of the transistor (13b) connected to the single pulse oscillation circuit (10b) becomes long, and as a result, the resistance (122b)
The time of the current (i1) flowing through is long. In accordance with this energization time, the pulse current output time of the pulse width control circuit (8b) is also expanded, the addition (Pb) shown by the broken line is added, and a wider pulse current (Pb) is added to the steady supply DC current. Will be superimposed.

Thus, the pulse current for flicker prevention
In addition to (P), a pulse current extension (Pb) for melting the precipitate (S) on the electrode surface is further superimposed, and as a result, the protrusions (e1) (e2) ... Precipitate upon disappearance
(S) also melts and spreads on the electrode surface, and the inter-electrode distance (L) between the electrodes (E1) and (E2) expands. When the inter-electrode distance (L) increases, the lighting voltage rises, which is input to one input terminal of the comparison circuit (32a) through the timer circuit (31a) and lights up from the set value of the sustain voltage setting function (33a). When the voltage becomes low, the comparison circuit (32
The output of a) becomes 0, the transistor (36a) turns off, the charging and discharging of the capacitor (35a ') stops, and the electrodes (E1) (E
Pulse current increase (Pb) to dissolve precipitate (S) in 2)
Pulse for preventing flicker in [Example 1]
Return to the operation of superimposing only (P). In this case, the pulse interval is governed by the capacity of the pulse interval adjusting capacitor (15a ') provided in the pulse oscillation circuit (10a).

On the contrary, when the amplified voltage (n × sense voltage) of the lighting current signal input to the one input terminal is smaller than the reference voltage of the sustain voltage setting function (33b) (the sense current is small), the lighting is performed. The voltage is judged to be high enough and the comparison circuit (32
No output from b), transistor (36b) remains off, capacitor (35b ') is not charged and voltage divider (12b)
The amplified lighting current signal (i0) of is shunted at the connection points (C1) and (C3) to become currents (i1) and (i2), which flow to the variable resistor (16b) and the resistor (122b). Pulse current with the same pulse width as
(P) will be superimposed on the steady-state DC current. As a result, the electrodes (E1) and (E2) are intermittently heated, and the discharge point is mainly fixed. In some cases, the electrodes (E1) and (E2) are intermittently heated to cause intermittent melting and disappearance of the protrusions (e1) (e2) on the electrode surface that cause flicker. Conceivable.

The discharge lamps (3a), (3b) according to the present invention are used by being mounted on a reflector (R), mounted on an optical device such as a projector, and used as a light source thereof.

[0068]

As described above, according to the present invention, not only the flicker at the time of lighting can be significantly reduced as compared with the conventional lighting method, but also the prevention of the narrowing of the inter-electrode distance due to the precipitates. However, it is still effective, and it has started to be used in optical devices such as projectors that require long-term arc stability (that is, flicker does not occur) and brightness maintenance in order to maintain excellent image quality for a long time. It is especially effective for existing short arc type discharge lamps.

[Brief description of drawings]

FIG. 1 is a sectional view of a discharge lamp to which the present invention is applied.

FIG. 2 is an enlarged cross-sectional view of the electrode tip portion of FIG.

FIG. 3 is an enlarged cross-sectional view showing a state in which flicker is generated by a protrusion generated at the electrode tip portion of FIG.

FIG. 4 is a lighting circuit diagram for a DC discharge lamp according to a first embodiment of the present invention.

5 is a drawing of an output waveform generated by the circuit of FIG.

6 is a pulse generator circuit diagram of FIG. 4;

FIG. 7 is a lighting circuit diagram for an AC discharge lamp according to a second embodiment of the present invention.

FIG. 8 is a drawing of an output waveform generated by the circuit of FIG.

FIG. 9 is a pulse generator circuit diagram of FIG. 7.

10 is a timing chart drawing of FIG. 9;

FIG. 11 is a lighting circuit diagram for a DC discharge lamp according to a third embodiment of the present invention.

FIG. 12 is a pulse generator circuit and voltage maintenance circuit diagram of FIG. 11.

FIG. 13 is a drawing of an output waveform generated by the circuit of FIG.

FIG. 14 is a lighting circuit diagram for an AC discharge lamp according to a fourth embodiment of the present invention.

FIG. 15 is a pulse generator circuit and voltage maintenance circuit diagram of FIG.

16 is a drawing of the output waveform generated by the circuit of FIG.

FIG. 17 is a diagram of a pulse generation circuit and a voltage maintenance circuit according to a fifth embodiment of the present invention.

FIG. 18 is a drawing of an output waveform generated by the circuit of FIG.

FIG. 19 is a pulse generator circuit and voltage maintenance circuit diagram of Embodiment 6 of the present invention.

FIG. 20 is a drawing of an output waveform generated by the circuit of FIG.

FIG. 21 is a graph showing the relationship between the discharge lamp voltage and the ballast output current.

FIG. 22 is a graph showing the relationship between the discharge lamp voltage and the ballast output power.

FIG. 23 is a conventional lighting circuit diagram for a DC discharge lamp.

FIG. 24 is a drawing of an output waveform generated by the circuit of FIG.

FIG. 25 is a conventional lighting circuit diagram for an AC discharge lamp.

26 is a drawing of an output waveform generated by the circuit of FIG. 25.

[Explanation of symbols]

(3a) DC discharge lamp

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nao Furukawa             Hyogo Prefecture Himeji City Tomicho Gakage Takamaru 703 Fe             Knicks Electric Co., Ltd. F-term (reference) 3K014 AA01 NA03                 3K072 AA11 AC11 AC20 BA05 BB01                       CA03 CA16 CB07 DD03 DD08                       DD10 DE02 DE04 DE06 EA07                       EB01 EB05 EB07 GA02 GB01                       GB03 GB18 HA10 HB03                 3K083 AA45 AA65 BA25 BA26 BA33                       BA41 BC16 BC37 BC42 BC47                       BD03 BD04 BD16 BD22 CA32

Claims (10)

[Claims] 1. A discharge lamp characterized in that, while the DC discharge lamp is being lit, an operating current obtained by superposing a pulse current at a constant interval on a DC current continuously supplied to the discharge lamp is supplied to the discharge lamp. Lighting method. 2. While the AC discharge lamp is being lit, a pulse current of a certain width is superposed at the same time as the half cycle of the alternating current continuously supplied to the discharge lamp or at a position delayed by a certain time from the rising. A method of lighting a discharge lamp, characterized in that the operating current is supplied to the discharge lamp. 3. The method for lighting a discharge lamp according to claim 1, wherein when the lighting voltage during steady lighting falls below a set value, the height of the superimposed pulse current is changed to a high value. A method of lighting a discharge lamp, characterized by: 4. The method of lighting a discharge lamp according to claim 1, wherein when the lighting voltage during steady lighting falls below a set value, the width of the superimposed pulse current is changed widely. A characteristic method of lighting a discharge lamp. 5. A DC ballast for supplying a constant power to a DC discharge lamp by a pulse width control circuit, an igniter connected in series to the DC ballast, for applying a starting voltage to the DC discharge lamp, and the DC ballast for the DC ballast. A lighting circuit for a discharge lamp, comprising a pulse generation circuit connected to a pulse width control circuit and configured to superimpose a pulse current on a DC ballast output current by generating a pulse. 6. An AC ballast for supplying constant power to an AC discharge lamp by a pulse width control circuit, an igniter connected in series to the AC ballast and applying a starting voltage to the AC discharge lamp, It is connected to a pulse width control circuit, generates a pulse current at the same timing as the switching of the AC current waveform of the AC ballast or at a certain time later than that, and starts up a half cycle of the AC current continuously supplied to the discharge lamp. A lighting circuit for a discharge lamp, comprising: a pulse generation circuit that superimposes the pulse current having a constant width at the same time or at a position delayed by a predetermined time from the rising. 7. The pulse generation circuit of the discharge lamp lighting circuit according to claim 5 or 6, wherein the lighting current of the discharge lamp during steady lighting is detected as a sense voltage by a sense resistor, and the sense voltage is detected during steady lighting. A lighting circuit for a discharge lamp, wherein a voltage maintaining circuit for increasing a pulse current to be superimposed is connected to a pulse width control circuit if the value is equal to or less than a set value. 8. The pulse generation circuit of the discharge lamp lighting circuit according to claim 5, wherein the lighting current of the discharge lamp during steady lighting is detected as a sense voltage by a sense resistor, and the sense voltage is detected during steady lighting. If it is less than the set value,
A lighting circuit of a discharge lamp, wherein a pulse width voltage maintaining circuit for increasing a width of a pulse current to be superimposed is connected to a pulse width control circuit. 9. The discharge lamp lighting circuit according to claim 5, a reflector having a discharge lamp mounting portion provided at the center of a concave reflecting surface portion, and a seal portion thereof mounted on the discharge lamp mounting portion. A light source device composed of a discharge lamp that is installed. 10. An optical device comprising: the light source device according to claim 9; and an optical system for irradiating a screen in front with light from a discharge lamp mounted on the light source device.