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Catalog Guide

Here is the explanation of how to use the catalog to select a lamp.


Shape and size are represented by a shape symbol (T means a tube) and a nominal value of a maximum diameter in milimeters (mm). Otherwise, a shape symbol and a maximum diameter are indicated in 1/8-inch standard in a parentheses.


Major dimensions are indecated in millimeters (mm). Value described in ( ) represents reference value only.


The design voltage (Unit symbol : V) indicates the applied voltage at which the lamp's design current luminous flux and average life can be utilized.


The term design current (Unit symbol : mA, A) indicates the current flow when a lamp's design voltage has been applied. The current flow value (design current) shall be within the range of ±10% unless otherwise stated.


As a luminous flux unit, LUMEN (Unit symbol :lm) is used usually in Japan and Europe, and MEAN SPHERICAL CANDLE POWER (Unit symbol : M.S.C.P.) is used in the United States of America. Both units are indicated in the catalog.
The relation between M.S.C.P. and LUMEN (lm) which is the total light quantity emitted from alight source is :

The tolerance range of luminous fiux is usually controlled within ±25%.


Average life is defined as the average time required to burn out the filament in the continuous lighting test in rigidly controlled laboratory conditions not having any shock, vibration or temperature changes at the lamp's design voltage within ±1% of voltage regulation. Average life at AC lighting and DC lighting are represented as AC AVG LIFE (unit symbol : hrs.) and DC AVG LIFE (Unit symbol : hrs.) respectively. Also, minimum life is defined as the time required to burn out the first filament in the continuous lighting test in rigidly controlled laboratory conditions not having any shock, vibration or temperature changes at the lamp's design voltage within 1% of voltage regulation.

Lamp life will depend on the lamp efficiency as shown in the formula below :

Since the life ratings for miniature lamps are so long, the theoretical life by performing accelerated life tests by operating the lamp at a accelerated voltage can be used. Theoretical life is calculated by taking the inverse proportion of the operating voltage to the power of 12 to 13. However, miniature lamp life, at DC voltage, may have only 50% or less of the calculated average life.


The length and diameter of a filament are decided by the voltage, current, luminous flux and average life, and filament shape is decided by the size of a bulb to use. An anchor may be attached to improve resistance against vibration or impact according to the purpose to use.

NOTE) Please note that there is a difference between rated voltage and design voltage.



Soft glass (softening point 605~625°C) is used in most of the lamps we produce.


It is necessary for some filaments to support it with a molybdenum wire to prevent a short circuit caused by deformation of a filament depend on its diameter and length.
It is also used to increase impact proof.


It is a tungsten wire winded in a coil.


A Dumet wire, a copper covered wire with an alloy of iron and nickel, is used for Sub Miniature Lamps, and a Ni plated Dument wire is used for Wedge Base Lamps.
Plating is available for a wire terminal of Sub Miniature Lamps on your request.


In lighting, inside of a lamp it is vacuumed by removing air to control the evaporation of a tungsten wire. Also, in some Wedge base lamps, inert gas (argon, krypton, xenon, etc.) is sealed for longer life or higher filament temperature.


Lamps may change their quality and characteristics due to the working conditions. We recommend to select more suitable lamps according to the following guidelines.


The degree of effect depends on the length and diameter of a filament. The longer or thinner a filament is, the more effect of vibration or shock it gets. Also, vibration or shock makes a filament deformed and a coil touched. Thus the life becomes shorter because of the increase of amperes and filament temperature. Therefore, we recommend to use as higher ampere lamps as possible because the diameter of a filament is decided by amperes.


We recommend to use the lamps as higher amperes and lower luminous flux as possible because the lower the efficiency (high amperes and low luminance) is, the longer the life is. Efficiency changes depend on wattage and luminous flux, and the relations are formulated as follows :


When a bulb is used in a high temperature, gas is generated from the glass, and life becomes shorter because of the effects of the gas. In this case, we recommend not to have high temperature conditions. If that is impossible, we recommend to use the lamps with bigger bulb diameter.

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