| 摘要 |
The apparatus to harden a dental mass, by light, has a pulsed operation acting on the material which is polymerized by the effect of light. During the main hardening time, the power profile has a cycle power pattern where a higher and a lower power value alternate with each other. During the main hardening time, the apparatus switches the light source on and off alternately. The lower power value is set so that the delivered light power is 25-60% of the maximum light power and especially 50%. The light source has an incandescent coil, which gives alternating bright and dim illumination. The light power is pulsed from the light source. The succession of high and low alternating power values is periodic during the main hardening time, with periods of 0.01-15.0 seconds and preferably 2 seconds. During the start time, the light power increases especially with an initial sharp rise followed by a flatter rise. At the end of the start phase, the light power is at a level which matches the low power value. The light source is controlled to maintain the constant required light power profile using a proportional integral derivative (PID) control which takes the dead time of the light source into account. The flanks of the light power increase, from the low level to the high level, have a pitch which is /-5% of the cycle period of the power profile during the main hardening time, and especially /-10%. The light source is a halogen lamp, which is still illuminated during the low light power phases. The light source can also be a laser diode or an array of light emitting diodes (LED). The light source is integrated into a manual instrument, and the control has a control stretch through the cable between the instrument and the supply station.
|
