Why are filament lamp shaped like pears?

Since Thomas Edison invented the first practical incandescent filament lamp the light bulb has become an indispensable part of People's Daily life. When we think of traditional incandescent lamps, a familiar shape often comes to mind - pear shape.

The historical origin of the pear-shaped bulb 

At first, the shape of Edison's experimental light bulb was not fixed, but went through many attempts and improvements. The final pear-shaped design was chosen, taking into account both practicality and aesthetics. This shape of the light bulb has not only become the industry standard, but also become the classic image of the light bulb. 

Heat dissipation performance 

1. Principle of thermodynamics: Incandescent lamp will produce a lot of heat when working, if it can not be dispersed in time, it will cause the filament to fuse. The pear-shaped design increases the area of contact with the air through its wide bottom, which is conducive to the diffusion of heat, thus improving the service life of the bulb. 

2. Heat convection effect: After the lamp is lit, the hot air will rise, and the cold air will sink, forming a natural convection. The pear-shaped structure matches this physical phenomenon so that heat can be evenly distributed, reducing the risk of local overheating.

Optical effect 

In addition to heat dissipation, the design of the pear-shaped bulb also takes into account the distribution of light: 

1. Uniform lighting: Because the filament inside the bulb is usually located near the top of the bulb, the pear-shaped design helps the light to spread around rather than concentrate in one direction, thus achieving a more uniform lighting effect. 

2. Reduce glare: By adjusting the shape of the bulb, it can effectively block the strong light directly into the eyes and reduce the visual discomfort caused by glare. 

Manufacturing process 

From a manufacturing point of view, pear-shaped bulbs also have their own unique advantages: 

1. Blowing process: In the early days, light bulbs mainly relied on manual blowing. The pear-shaped design is easy for craftsmen to operate, but also to ensure that the bulb wall thickness is uniform, to avoid the use of local weakness caused by rupture. 

2. Standardized production: With the advancement of the industrialization process, the production of light bulbs has gradually realized mechanization. As a standard form, pear shape is easy to mold and conducive to large-scale production.