High pressure discharge lamp lighting apparatus

Abstract

A high pressure discharge lamp lighting apparatus comprises a high pressure discharge lamp including a discharge container made of quartz glass in which mercury and halogen is enclosed, and a first and second electrodes in which the first electrode is larger than the second electrode in size and face each other, a power supply section which turns on the discharge lamp by impressing a voltage of opposite polarity by turns between the pair of electrodes of the high pressure discharge lamp. In the lamp lighting apparatus, a control is carried out by the power supply section, so that a first period during which a positive voltage is impressed to the first electrode is longer than a second period during a positive voltage is impressed to the second electrode.

Description

BRIEF DESCRIPTION OF DRAWINGS

Other features and advantages of the present high pressure discharge lamp lighting apparatus will be apparent from the ensuing description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows the structure and an example of the current waveform of a discharge lamp which is used in an embodiment;

FIG. 2 shows the luminance distributions of an AC discharge lamp and a DC discharge lamp;

FIG. 3A shows a measurement apparatus for measuring lamp illuminance while the duty ratio is changed;

FIG. 3B shows the relation between the duty ratio and the illuminance ratio which is a measurement result;

FIG. 3C shows luminance distribution;

FIG. 4 shows the structure of a discharge lamp lighting apparatus according to an embodiment;

FIG. 5 shows the relation of the set value of a lamp voltage and a duty ratio;

FIG. 6 is a functional block diagram of a control unit shown in FIG. 4;

FIG. 7 is a diagram for explaining control of a duty ratio;

FIG. 8 is a timing chart at the time of a lamp lighting start;

FIG. 9 is a flow chart showing an operation of a control unit;

FIG. 10 shows schematic structure of a projector apparatus which uses a DMD element;

FIG. 11 shows a schematic structure of the projector apparatus using a liquid crystal panel;

FIG. 12 is a diagram for explaining a problem when a projector apparatus using a DMD element is miniaturized; and

FIG. 13 shows a simulation result of an arc length, an etendue, and a light collecting rate.

Claims

1. A high pressure discharge lamp lighting apparatus comprising: a high pressure discharge lamp including a discharge container made of quartz glass in which mercury and halogen is enclosed, and a first and second electrodes in which the first electrode is larger than the second electrode in size and face each other,a power supply section which turns on the discharge lamp by impressing a voltage of opposite polarity by turns between the pair of electrodes of the high pressure discharge lamp,wherein a control is carried out by the power supply section, so that a first period in a cycle of a positive voltage impressed to the first electrode is longer than a second period in a cycle of a positive voltage impressed to the second electrode.

2. The high pressure discharge lamp lighting apparatus according to claim 1, wherein the power supply section detects a lamp voltage, and a ratio of the first period and the second period is changed according to the lamp voltage.