Metal vapor discharge lamp and lighting apparatus capable of stable maintenance of characteristics

A metal vapor discharge lamp having an arc tube, wherein

• the arc tube includes a container made of translucent ceramic, the container being divided into a main tube portion and two narrow tube portions respectively extending out from both ends of the main tube portion,
• a discharge space is formed in the main tube portion with a light emission metal being enclosed in the discharge space,
• an electrode is deposited in each narrow tube portion, a coil being wound around the electrode at an end thereof facing the discharge space,
• an electrode supporting member is inserted in each narrow tube portion and connected to the other end of the electrode,
• the arc tube is sealed by a sealing material that is inserted into each space between each electrode supporting member and each narrow tube portion,
• a length of each electrode is in a range of (0.041P+0.5) mm to (0.041P+8.0) mm inclusive, wherein “P” represents a lamp power in watts, and
• the lamp power is in a range of 70 watts to 400 watts inclusive.

A metal vapor discharge lamp having an arc tube, wherein

• the arc tube includes a container made of translucent ceramic, the container being divided into a main tube portion and two narrow tube portions respectively extending out from both ends of the main tube portion,
• a discharge space is formed in the main tube portion with a light emission metal being enclosed in the discharge space,
• an electrode is deposited in each narrow tube portion, a coil being wound around the electrode at an end thereof facing the discharge space,
• an electrode supporting member is inserted in each narrow tube portion and connected to the other end of the electrode,
• the arc tube is sealed by a sealing material that is inserted into each space between each electrode supporting member and each narrow tube portion, and
• a length of each narrow tube portion is in a range of (0.032P+3.5) mm to (0.032P+8.0) mm inclusive, wherein “P” represents a lamp power in watts.

A metal vapor discharge lamp having an arc tube, wherein

• the arc tube includes a container made of translucent ceramic, the container being divided into a main tube portion and two narrow tube portions respectively extending out from both ends of the main tube portion,
• a discharge space is formed in the main tube portion with a light emission metal being enclosed in the discharge space,
• an electrode is deposited in each narrow tube portion, a coil being wound around the electrode at an end thereof facing the discharge space,
• an electrode supporting member is inserted in each narrow tube portion and connected to the other end of the electrode,
• the arc tube is sealed by a sealing material that is inserted into each space between each electrode supporting member and each narrow tube portion, and
• a length of each narrow tube portion is in a range of (0.032P+3.5) mm to (0.032P+6.0) mm inclusive, wherein “P” represents a lamp power in watts.

A lighting apparatus that includes a main body, a metal vapor discharge lamp disposed in the main body, and a lighting circuit apparatus connected to the metal vapor discharge lamp, the metal vapor discharge lamp having an arc tube, wherein

• the arc tube includes a container made of translucent ceramic, the container being divided into a main tube portion and two narrow tube portions respectively extending out from both ends of the main tube portion,
• a discharge space is formed in the main tube portion with a light emission metal being enclosed in the discharge space,
• an electrode is deposited in each narrow tube portion, a coil being wound around the electrode at an end thereof facing the discharge space,
• an electrode supporting member is inserted in each narrow tube portion and connected to the other end of the electrode,
• the arc tube is sealed by a sealing material that is inserted into each space between each electrode supporting member and each narrow tube portion, and
• a length of each electrode is in a range of (0.041P+0.55) mm to (0.041P+8.0) mm inclusive, wherein “P” represents a lamp power in watts.

A lighting apparatus that includes a main body, a metal vapor discharge lamp disposed in the main body, and a lighting circuit apparatus connected to the metal vapor discharge lamp, the metal vapor discharge lamp having an arc tube, wherein

• the arc tube includes a container made of translucent ceramic, the container being divided into a main tube portion and two narrow tube portions respectively extending out from both ends of the main tube portion,
• a discharge space is formed in the main tube portion with a light emission metal being enclosed in the discharge space,
• an electrode is deposited in each narrow tube portion, a coil being wound around the electrode at an end thereof facing the discharge space,
• an electrode supporting member is inserted in each narrow tube portion and connected to the other end of the electrode, the arc tube is sealed by a sealing material that is inserted into each space between each electrode supporting member and each narrow tube portion, and
• a length of each narrow tube portion is in a range of (0.032P+3.5) mm to (0.032P+8.0) mm inclusive, wherein “P” represents a lamp power in watts.