Patent Application
20170149206
This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 104139267 filed in Taiwan, R.O.C. on Nov. 25, 2015, the entire contents of which are hereby incorporated by reference.
The disclosure relates to a control method of speeding up light emission of light amplification by simulated emission of radiation (Laser) diodes.
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. All photons outputted by a laser have the same phase, direction and amplitude so laser light has a high intensity, directionality, a monochromatism and coherences. Due to the properties of laser light, industrial lasers has been applied to applications of precision machining in various industries. A laser can provide a focused high energy thermal source for applications of various fields, such as high speed welding, cutting, marking, engraving, coloring, surface heat treatment or measurement.
Presently, a more common practice is that one or more laser diodes cooperate with a driving device to produce laser light. A user can use the driving device to control the laser diode to emit light or not to process workpieces according to the states of the workpieces. However, existed driving devices generally cannot rapidly turn on laser diodes to produce laser light, resulting in a lower processing quality usually caused by the delay of light emission of laser diodes during workpiece machining.
According to one or more embodiments, the disclosure provides a control method of speeding up light emission of laser diodes. The control method includes the following steps. Boost a supply voltage from a first voltage potential to a second voltage potential before an emission period starts. At the beginning of the emission period, conduct a current path comprising the laser diode and a current source. One terminal of the laser diode is coupled to the current source, and the other terminal of the laser diode connects to the supply voltage. When the current path is being conducted, the current source is in the transient state and provides a transient driving current; and the voltage difference between the two terminals of the laser diode is generated in response to the second voltage potential and is related to the transient driving current. When the transient driving current is larger than a threshold, the laser diode emits light.
The present disclosure will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only and thus are not limitative of the present disclosure and wherein:
In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawings.
Please refer to
Multiple voltage parameters and current parameters are presented in
The voltage control module 14 selectively provides the supply voltage VDD and even selectively boosts the supply voltage VDD from a first voltage potential V1 to a second voltage potential V2. The first voltage potential V1 and the second voltage potential V2 are exemplary but are not used to limit the range of the supply voltage VDD and the amount of output potentials. The current control module 18 controls the current source 124 to selectively provide a driving current iD. The system control module 16 commands the voltage control module 14 and the current control module 18 according to a power setting signal and according to the power setting signal, selectively outputs a control signal S for turning on the switch unit 129. In other words, the system control module 16, according to an output power value indicated by the power setting signal, commands the voltage control module 14 and the current control module 18 to correspondingly output the supply voltage VDD and the driving current iD. In an embodiment, when the control signal S is at a high voltage potential, the switch unit 129 is turned on. Other embodiments may be contemplated in which the switch unit 129 is turned on according to the control signal S at another voltage potential.
The current source 124 and the switch unit 129 are carried out by, for example, but not limited to, at least one bipolar junction transistor (BJT) or at least one metal-oxide-semiconductor field-effect transistor (MOSFET).
Also, the disclosure provides a control method of speeding up the light emission of laser diodes, as described in
Please refer to
At the time point T1, the control signal S is modulated to a high voltage potential so the switch unit 129 is turning on. Also, the laser diode 122, the switch unit 129 and the current source 124 constitute a current path between an input node of the supply voltage VDD and a ground end, and the laser diode driving module 12 is in a transient state. Herein, the laser diode 122 is conducted but has not emitted light, the voltage potential VK decreases and gradually approaches the voltage potential VC, and the voltage potential VC increases and gradually approaches the voltage potential VK. Later than the time point Ti, the difference between the voltage potential VA and the voltage potential VK gradually increases; therefore, the driving current iD at the transient state also increases and achieves its peak value at around the time point T2. In this embodiment, the driving current iD at around the time point T2 becomes larger than the threshold current of the laser diode 122. The laser diode 122 starts emitting light at around the time point T2. In practice, the time point which the laser diode 122 starts emitting light is based on the physical properties of the laser diode 122 and is not limited by the above embodiment.
In an embodiment, after the time point T1 at which the switch unit 129 is turned on, boosting the supply voltage VDD to the second voltage potential V2 is stopped. Therefore, the supply voltage VDD gradually decreases after the time point T1, as shown in
After the time point T3, the laser diode driving module 12 gradually becomes stable so the supply voltage VDD is close to the first voltage potential V1 and is a constant value. The voltage potential VA is substantially a constant value close to the first voltage potential V1. Moreover, the variations of the voltage potentials VK and VC and the driving current iD gradually become substantially smooth. In the drawing, the transient peak of the driving current iD is larger than the steady-state potential of the driving current iD so that the laser diode 122 is rapidly turned on and emits light at the transient state.
At the time point T4, the control signal S is modulated to a low voltage potential so the switch unit 129 is turned off. Herein, the supply voltage VDD boosts to the second voltage potential V2 again. In practice, the increasing speed of the supply voltage VDD is related to the capacitance of the capacitor 128. Because the switch unit 129 is turned off, the voltage potentials VA and VK increase in response to the increase of the supply voltage VDD. On the other hand, the driving current iD and the voltage potential VC gradually drop to a constant value since the switch unit 129 is turned off. At the time point T5, the laser diode driving module 12 gradually becomes stable, and each voltage parameter and each current parameter also gradually become stable. Once the control signal S is pulled up to a high voltage potential again, the above process will proceed again.
In view of the above control method of speeding up the light emission of laser diodes in the disclosure, the transient driving current of the laser diode increases in response to the boosting the supply voltage so the laser diode can rapidly emit light after being turned on by the transient driving current, which is higher than a conventional driving current. Also, the laser diode stably emits light in response to the steady-sate current after the circuit becomes stable. Therefore, the laser diode synchronously reacts to a user's command or a controller's control as far as it can. While the controller gives a command, the laser diode may rapidly emit light. Smaller delay of light emission can enhance the processing quality provided by the laser diode so the laser diode can be applied to a complicated precision machining field.
| Number | Date | Country | Kind |
|---|---|---|---|
| 104139267 | Nov 2015 | TW | national |
