JPH04296496A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To efficiently use a lamp, prevent the reduction of light flux of the lamp, and increase the dimming ratio even in high temperature area. CONSTITUTION:An oscillating circuit 7 for determining the oscillating frequency of an inverter circuit 4 for lighting a discharge lamp 5 is provided. A temperature detecting means 8 for detecting the tube wall temperature of the discharge lamp 5 is provided. According to the output of the temperature detecting means 8, the oscillating circuit 7 is controlled by a control circuit 9 so as to increase the supplied power from the inverter circuit 4 to the discharge lamp 5 at the time of low temperature. At the time of high temperature, it is controlled in the direction of lowering the tube wall temperature of the lamp so as to increase the luminescent efficiency. Therefore, the higher the temperature, the more the supplied power from the inverter circuit 4 to the discharge lamp is reduced.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention supplies DC power obtained by rectifying and smoothing a commercial power source to an inverter circuit including switching elements, and supplies high-frequency power from the inverter circuit to a discharge lamp such as a fluorescent lamp. The present invention relates to a discharge lamp lighting device that supplies power to light a discharge lamp.

0002

[Prior Art] Conventionally, in the field of lighting equipment, particularly in the field of lighting equipment equipped with discharge lamps, high-frequency lighting using an inverter circuit has been used as a discharge lamp lighting device for lighting a discharge lamp to improve the efficiency of light output and control the output. Since this is effective in terms of ease of operation, many discharge lamp lighting devices using inverter circuits have been developed.

However, no matter how easy the inverter circuit is in terms of output control, the current situation is that it is not possible to fully control the characteristics of the discharge lamp itself. As a characteristic of a discharge lamp, the light output when the current flowing through the discharge lamp is constant, regardless of the temperature of the tube wall of the discharge lamp, or in other words, the luminous efficiency, as shown in Figure 5, the luminous efficiency is plotted on the vertical axis. , when the tube wall temperature is plotted on the horizontal axis, the characteristic is a negative quadratic curve with respect to changes in the tube wall temperature.

As is clear from FIG. 5, the luminous efficiency decreases at both low and high temperatures compared to room temperature. In addition, in terms of startability, when the current of the discharge lamp is small, there is a problem in that starting at low temperatures becomes difficult. In order to solve these problems, for example, Japanese Patent Application No. 1983-245276 discloses improvements such as improving startability at the time of starting and ensuring good output.

[0005] Even if the lighting equipment has good startability, the internal temperature rises after the discharge lamp is turned on, and the light output until it stabilizes follows the course shown in Fig. 6. In FIG. 6, the solid line A1 shows the change in light output when the light is fully lit, and the solid line A2 shows the change in the light output when the light is dimmed. When the discharge lamp is started when the lamp is fully lit, the temperature of the tube wall of the discharge lamp has not yet risen, so as shown by the solid line A1 in Figure 6, the output becomes high, and then as the temperature inside the lighting equipment rises, the tube wall temperature of the discharge lamp increases. The wall temperature also rises due to the heat generated by the discharge lamp, and as shown in Figure 5, as the temperature increases, the luminous efficiency decreases, so the light output gradually decreases and reaches a constant value at a certain stable point. becomes.

However, when lighting is dimmed, the current applied to the discharge lamp is reduced, so the temperature rise of the discharge lamp itself is small, and the output remains constant with an increasing curve as shown by the solid line A2 in FIG. . In other words, when all lights are on, point A in FIG. 5 is the stable luminous efficiency point,
This is because during dim lighting, point B is the luminous efficiency point during stable lighting.

[0007]

[Problems to be Solved by the Invention] Recently, however, due to the diversification of lighting fixture designs, lighting fixtures in which the discharge lamp is not exposed at all are on the market. In such lighting equipment, the temperature inside the lighting equipment rises compared to conventional lighting equipment, so the temperature of the tube wall of the discharge lamp rises, and the temperature of the tube wall of the discharge lamp is high both when the lamp is fully lit and when it is dimmed. becomes stable.

[0008] At this time, the luminous efficiency when the lamp is fully lit deteriorates further, resulting in a reduction in lamp light output. On the other hand, when the lighting is dimmed, the luminous efficiency improves,
This results in an increase in the lamp light output, and as a result, the dimming ratio (dimmer lighting output in stable mode/total lighting output in stable mode) during stable conditions becomes larger, and the difference between full lighting and dimming lighting increases. A problem arises in that the amount of light does not change.

The present invention has been provided in view of the above points, and provides a discharge lamp that can efficiently use the lamp, prevent a decrease in the luminous flux of the lamp, and further increase the dimming ratio even in a high temperature region. The purpose is to provide a lighting device.

0010

[Means for Solving the Problems] The present invention provides a direct current power supply,
An inverter circuit that converts this DC power into high-frequency power, a discharge lamp that is powered by the inverter circuit, a temperature detection means that detects the temperature inside the lighting equipment, and a control unit that controls the oscillation state of the inverter circuit. According to
Switching between full lighting and dimming lighting of the discharge lamp, and
and a control circuit that reduces the output of the inverter circuit by controlling the oscillation state of the inverter circuit in response to a temperature rise within the lighting fixture based on the output of the temperature detection means.

[0011] Furthermore, when the control circuit reduces the output of the inverter circuit in response to a rise in temperature within the lighting equipment, the output of the inverter circuit is reduced more when the lighting is dimmed than when the lighting is fully lit. There is.

0012

[Operation] The control circuit reduces the output of the inverter circuit by controlling the oscillation state of the inverter circuit in response to a rise in temperature within the lighting fixture. Also, when the control circuit reduces the output of the inverter circuit in response to a rise in temperature within the lighting equipment,
The output of the inverter circuit is controlled to be reduced more when the lamp is dimmed than when the lamp is fully lit.

[0013]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. Generally, in a fluorescent lamp, as described above (FIG. 5), the luminous efficiency reaches its maximum when the tube wall temperature is around 45° C., and the luminous efficiency decreases whether the tube wall temperature becomes low or high. Therefore, first, when the temperature is low, the temperature of the tube wall of the lamp is controlled to be high in order to increase the luminous efficiency.

Therefore, the lower the temperature becomes, the more power is supplied from the inverter circuit to the discharge lamp. or,
At high temperatures, the lamp tube wall temperature is controlled to be lower in order to increase luminous efficiency. Therefore, as the temperature increases, the power supplied from the inverter circuit to the discharge lamp is reduced. By controlling in this manner, the lamp can be used more efficiently, and a decrease in light output due to a decrease in lamp luminous efficiency at low and high temperatures can be prevented. Furthermore, during dimming lighting, by further reducing the power supplied from the inverter circuit to the discharge lamp at high temperatures, the dimming ratio at high temperatures can be reduced.

[0015] A detailed explanation will be given below. FIG. 1 shows a discharge lamp lighting device according to an embodiment of the present invention. In FIG. 1, a DC power supply 1 includes, for example, a commercial power supply 2 and a rectification/smoothing circuit 3 that rectifies and smoothes the voltage of the commercial power supply 2. The inverter circuit 4 is configured to include a switching element and a resonant circuit, and its internal configuration may be of any configuration as long as it can change the oscillation frequency.

The discharge lamp 5 such as a fluorescent lamp is supplied with power from the inverter circuit 4 and is lit at high frequency.
The oscillation frequency of the inverter circuit 4 is determined by the oscillation frequency of the oscillation circuit 7. Further, the drive circuit 6 drives the switching elements of the inverter circuit 4 based on the oscillation output of the oscillation circuit 7. The temperature detection means 8 detects the temperature inside the lighting fixture, for example, the temperature of the tube wall of the discharge lamp 5.

The control circuit 9 controls the oscillation state of the inverter circuit 4 by supplying a signal to the oscillation circuit 7 to switch between full lighting and dimmed lighting of the discharge lamp 5, and also controls the temperature detection means 8. Depending on the output, similarly to the above, a signal is given to the oscillation circuit 7 to control the oscillation state of the inverter circuit 4 and change the output of the inverter circuit 4.

In this case, the control circuit 9 specifically switches the oscillation frequency of the oscillation circuit 7 using full lighting/dimming lighting switching means (not shown) such as a switch, so that the discharge lamp 5 can be turned on or off. The output of the inverter circuit 4 is changed by switching the dimmed lighting and changing the oscillation frequency of the oscillation circuit 7 based on the output of the temperature detection means 8.

FIG. 2 shows a specific example of the control circuit 9, etc. As the temperature detection means 8, a positive temperature coefficient thermistor or the like is used to vary the resistance value according to temperature changes, thereby changing the current of the current mirror circuit. Therefore, the charging time for capacitor C1 is varied. By varying the charging time of the capacitor C1, the frequency of the oscillation circuit 7 is varied and the inverter circuit 4 is controlled.

With the above-described configuration, this discharge lamp lighting device is capable of switching between full lighting and dimming of the discharge lamp 5, as well as controlling the oscillation of the inverter circuit 4 according to the output of the temperature detecting means 8. Since the state is controlled, even if the luminous efficiency of the discharge lamp 5 changes in both full lighting and dimmed lighting due to temperature changes within the lighting equipment, the output of the inverter circuit 4 changes accordingly. I can do things.

Therefore, when the temperature is low, the output of the inverter circuit 4 can be increased as the temperature becomes lower, and when the temperature is high, the output of the inverter circuit 4 can be decreased as the temperature becomes higher. possible, low temperature,
It is possible to prevent a decrease in luminous flux due to a decrease in luminous efficiency at high temperatures. Furthermore, by further reducing the output of the inverter circuit 4 at high temperatures during dimming lighting, the dimming ratio can be reduced.

In FIG. 3, the temperature characteristics of the lamp current of the lighting device according to the embodiment of the present invention are shown by a solid line. In addition, this temperature characteristic is
The ambient temperature of the lamp was kept constant at 25°C, and the temperature of the lighting device was varied. Furthermore, the broken line indicates the temperature characteristics of the conventional lighting device. As shown in FIG. 3, in the present invention, the temperature characteristics of the lamp current during full lighting and the temperature characteristics of the lamp current during dimmed lighting have a negative slope with respect to the rise in ambient temperature. Further, the slope of the lamp current during dim lighting is larger than the slope of the lamp current during full lighting.

FIG. 4 shows the fixture ambient temperature characteristic of the light output of a lighting fixture incorporating a lighting device having the lamp current temperature characteristic shown by the solid line in FIG. 3 of the present invention. Incidentally, the broken line represents the light output vs. appliance ambient temperature characteristic in the case of an appliance incorporating the lighting device with the conventional temperature characteristic shown by the broken line in FIG.

[0024]

[Effects of the Invention] As described above, the present invention includes a DC power source, an inverter circuit that converts the DC power source into high frequency power,
A discharge lamp that is powered by the inverter circuit and lit, and a temperature detection means that detects the temperature inside the lighting equipment.
By controlling the oscillation state of the inverter circuit, the discharge lamp can be switched between full lighting and dimming, and the oscillation of the inverter circuit can be caused by controlling the oscillation state of the inverter circuit. and a control circuit that reduces the output of the inverter circuit by controlling its state, so that the control circuit controls the oscillation state of the inverter circuit in response to a temperature rise within the lighting equipment. By reducing the output of the inverter circuit, the output of the inverter circuit is controlled to decrease in response to a rise in temperature within the lighting equipment, so the luminous efficiency of the lamp is reduced at low and high temperatures. Fluorescent lamps can be used at points closer to good points, allowing lamps to be used more efficiently.
This has the effect of preventing a decrease in luminous flux at low and high temperatures.

Further, in claim 2, when the control circuit reduces the output of the inverter circuit in response to a rise in temperature within the lighting equipment, the output of the inverter circuit is lower when the lighting is dimmed than when the lighting is fully lit. Since the output of the inverter circuit is further reduced in response to the temperature rise during dimming, it is possible to reduce the dimming ratio at high temperatures. .

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the invention.

FIG. 2 is a block diagram partially showing a specific circuit.

FIG. 3 is a diagram showing the temperature characteristics of lamp current.

FIG. 4 is a diagram showing the characteristics of light output and ambient temperature.

FIG. 5 is a diagram showing the characteristics of luminous efficiency and tube wall temperature.

FIG. 6 is a diagram showing the relationship between light output and time.

[Explanation of symbols]

1 DC power supply 4 Inverter circuit 5 Discharge lamp 8 Temperature detection means 9 Control circuit

Claims (2)

[Claims] 1. A DC power supply, an inverter circuit that converts the DC power into high-frequency power, a discharge lamp that is lit by being supplied with power from the inverter circuit, a temperature detection means that detects the temperature inside the lighting equipment, and the above-mentioned. By controlling the oscillation state of the inverter circuit, the discharge lamp can be switched between full lighting and dimmed lighting, and the oscillation state of the inverter circuit can be controlled in response to a temperature rise in the lighting equipment by the output of the temperature detection means. and a control circuit that reduces the output of the inverter circuit by controlling the inverter circuit. [Claim 2] When the control circuit reduces the output of the inverter circuit in response to a rise in temperature within the lighting equipment, the output of the inverter circuit is reduced more when the lighting is dimmed than when the lighting is fully lit. The discharge lamp lighting device according to claim 1, characterized in that: