TWM659881U - Automatic power writing spot emitter - Google Patents

Abstract

This invention is about an Auto Power Write (APW) spot emitter, which is an Auto Power Write circuit configured as a circuit board or IC structure, and directly mounted on a base to control the laser power; a photodetector diode is mounted on the Auto Power Write circuit; a PWM control connected to the third pin of the base is used for writing functions to set the laser output power and PWM to adjust the laser rate; an adjustment circuit is used according to an adjustment code (Trim The resistor value is changed by using a decoder output to select different resistance values for writing, and the writing pin is the same as the PWM control pin 3; thereby, the light power value of the laser diode is detected by the photodiode, and the light power change is notified by the circuit feedback and the current compensation is made in real time, so that the light power can be stably maintained at the power value written by the automatic power writing circuit (APW IC). At the same time, the IC is designed with a protection circuit, so that the user can safely control the laser diode, and it is packaged in a single TO-CAN to achieve the goal of small size and low cost.

Description

Automatic power writing spot emitter

This work is about a light spot emitter, especially a light spot emitter with Auto Power Write (APW).

Since the advent of laser diodes (LD), they have been applied to many fields such as optical communication, optical recording and optical storage. There are two types of laser diodes (LD): edge-emitting type and surface-emitting type. Surface-emitting LD must be packaged to prevent dust from entering and eliminate the impact of ambient temperature changes on its performance, so as to ensure the stability of its products.

Next, the commonly used LD packaging method adopts the TO-CAN structure, and its structure is shown in Figure 1. The LD package (100) includes: a base (110), a plurality of electrical connection terminals (120), a photodetector (130), a laser (140), a packaging cover (150) and an optical lens (160). This type of patent is found in previous cases such as US Patent No. 5,835,514.

Furthermore, the luminescence characteristics of laser diodes are easily affected by the ambient temperature. As the current and optical power increase during driving, the component will also generate higher temperature, further causing the optical attenuation value to increase. Therefore, semiconductor lasers are generally equipped with external circuits to control the input current and use feedback control to detect the optical power output to instantly compensate for the problem of laser optical power attenuation caused by temperature.

As shown in FIG. 2A, which is the applicant's previously owned Taiwan Patent No. M386685, it discloses a laser diode device (900), which includes: a base (200), which is set as a lead frame (200a) type structure in this embodiment, and three conductive contacts (210) are provided on it, and the conductive contacts (210) are extended from the lead frame (200a) to form a first pin (211), a second pin (212) and a third pin (213). Please refer to FIG. 2B at the same time, the first and second pins (211) and (212) are connected to positive and negative power sources respectively, and the third pin (213) is connected to an external resistor (800) to set the laser power. A photodetector sub-mount (300) is arranged on the surface of the conductive frame (200a) for detecting laser power and carrying a laser diode crystal (500). A PD (Photo Diode) photodetector (400) structure is arranged inside the sub-mount (300). An automatic power control (APC) circuit (600) is configured in the form of a circuit board or IC, and is directly disposed on the base (200) so that it is placed in the same package structure as the laser diode die (500), and is electrically connected to a predetermined conductive interface (210), the laser diode die (500) and the photodetector (400) by wire bonding (700), thereby forming a laser diode driving element, and further forming a laser diode device (500) with a built-in APC circuit; however, it is found that the previous case is connected to the external resistor (800) through the third pin (213) to set the laser power, and the external resistor (800) is a variable resistor (VR).

In addition, the applicant disclosed a dot projector with automatic power control in the previous Taiwan invention patent No. I691134 (US Patent No. 10,418,780 B1), which integrates an automatic power control IC with a photodetector diode, a fixing base, a laser diode, a light reflection element, a housing, a collimator and a diffraction optical element on a substrate to solve the problem that the prior art is more complicated to assemble, has a larger volume and cannot use semiconductor surface mounting technology to achieve rapid automated production, thereby improving the performance of simple assembly, thin volume and low production cost.

As shown in FIG. 3 , the circuit structure of the automatic power control IC 32 includes the supply voltage contact (P1) being coupled in series with the photodiode 321 and in parallel with a resistor (R) and a first ESD (i.e., Electro-Static Discharge: Electrostatic Discharge) circuit (E1), and the first ESD circuit (E1) is coupled in parallel to a ground terminal (G); a logic circuit (LE) is respectively coupled in series to the resistor (R) and the current setting contact (P3); a current amplifier circuit (CA) is coupled in series to the photodetector diode 321; an error amplifier (EA) is coupled in parallel to the current amplifier circuit (CA); a protection circuit (U) includes a reference voltage unit (U1), an over-temperature protection unit (U3) and a low voltage lock unit (U3), which are coupled in parallel to the error amplifier (E A); a transistor (T) is respectively coupled in series to the error amplifier (EA), the laser diode 34 output contact (P5) and the ground terminal (G); a current monitoring circuit (CM) is respectively coupled in parallel to the ground terminal (G); a second ESD circuit (E2) is respectively coupled in parallel to the current setting contact (P3) and the ground terminal (G); a third ESD circuit (E3) is respectively coupled in parallel to the current setting contact (P3) and the ground terminal (G); a variable resistor (VR) is respectively coupled in series to the photodetector diode output contact (P4) and the ground terminal (G).

However, it is found that the laser power adjustment of the previous proposal is also achieved through the external variable resistor (VR); for the production of the light spot emitter, there are still problems such as complex assembly, large size and high cost, so there is still room for improvement.

In view of the above problems, the applicant continues to conduct research and development, with solving the above deficiencies as the main topic.

The main purpose of this invention is to provide an Auto Power Write (APW) light spot emitter, which has a photodetector diode to detect the optical power value of the laser diode, and to notify the optical power change in the form of circuit feedback and make current compensation in real time, so that the optical power can be stably maintained at the power value written in the Auto Power Write Circuit (APW IC).

Another purpose of this invention is to provide an Auto Power Write (APW) light spot emitter, which is designed with a protection circuit in the IC, allowing users to safely control the laser diode, and package it in a single TO-CAN to achieve the goal of small size and low cost.

To achieve the above purpose, the technical means adopted by the invention include: a base, the base is set as a lead frame structure of TO-CAN package, and a first pin, a second pin, and a third pin are provided on the base, and the first and second pins are connected to the positive and negative power sources respectively; a laser diode is set on the primary fixing seat of the base; a photodetector diode is located on the light-emitting surface of the laser diode to detect the laser power; its characteristics are: an automatic power writing circuit (APW IC), the automatic power writing circuit is configured as a circuit board or an IC structure, and is directly configured on the base to control the laser power; the photodetector diode is configured on the automatic power writing circuit; the automatic power writing circuit comprises: the first pin is coupled in series with the photodetector diode, and is coupled in parallel with a first antistatic protection circuit, and the first antistatic protection circuit is coupled in parallel with a ground terminal; a logic circuit is coupled between the first pin and the third pin respectively; an error amplifier is coupled in parallel with the photodetector diode, responsible for the loop and determining the laser diode current; a protection circuit connected to the error amplifier as a reference voltage and to prevent low voltage malfunction; a transistor coupled in series to the error amplifier, an output contact of the laser diode and the ground terminal; a current monitoring circuit connected in parallel to the transistor and coupled to the ground terminal; a PWM control connected to the third pin and coupled between the error amplifier and the transistor for writing functions to set the laser output power and PWM to adjust the laser rate; and an adjustment circuit connected to the photodetector diode and the ground terminal, the adjustment circuit adjusting the laser output power according to an adjustment code (Trim The invention discloses a method for changing the resistance value of a resistor ( _RA ) by using a decoder output to select different resistance values for writing, and the writing pin is the same as the PWM control pin, thereby detecting the optical power value of the laser diode by the photodiode, notifying the optical power change by circuit feedback and making current compensation in real time, so that the optical power can be stably maintained at the power value written by the automatic power writing circuit (APW IC).

According to the aforementioned features, the adjustment circuit connects a plurality of switches (SW1), (SW2) to (SWn) at the plurality of joint positions of the resistor, and selectively turns on the switches (SW1) to (SWn) according to the adjustment code (TRC), thereby short-circuiting a portion of the resistor ( _RA ), thereby changing the resistance value.

According to the aforementioned features, the automatic power writing circuit may further include a second anti-static protection circuit, which is arranged between the laser diode output contact and the ground terminal; and a third anti-static protection circuit, which is connected in parallel between the third pin and the ground terminal.

According to the aforementioned features, the automatic power writing circuit may further include a slow start circuit to prevent overcurrent during startup, and a unidirectional diode is provided between the first pin and the photodetector diode.

According to the aforementioned features, the base may further include a metal cover and a coated glass.

According to the above-mentioned characteristics, the protection circuit may include: an over current protection, an over temperature protection, a short circuit protection, and a reverse voltage protection.

With the help of the above-mentioned technical means, this creation is to match the photodetector diode (PD) and APW (Auto Power Write) IC inside the TO-CAN package. This design architecture can use the photodetector diode (PD) to detect the optical power value of the laser diode (LD), and use the circuit feedback to notify the optical power change and make current compensation in real time, so that the optical power can be stably maintained at the power value written by the APW IC; at the same time, the IC is designed with safety protection such as protection circuits, so that users can safely control the laser diode. This package is packaged in a single TO-CAN to achieve the goal of small size and low cost.

10: Base

11:Metal cover

12: Coated glass

20: Secondary fixed seat

30: Laser diode

40: Photodetector diode

50: Automatic power writing circuit

501: Soft start circuit

502: One-way diode

51a: The first anti-static protection circuit

51b: Second anti-static protection circuit

51c: The third anti-static protection circuit

52:Logic circuit

53: Error amplifier

54: Protection circuit

55: Transistor

56: Laser diode output contact

57: Current monitoring circuit

58:PWM control

59: Trimming code

591:Decoder

60: Automatic power writing light spot emitter

P1: First pin

P2: Second pin

P3: Third pin

Figure 1 is a schematic diagram of the structure of a conventional LD in TO-CAN packaging.

Figure 2A is a schematic diagram of the structure of Taiwan Patent No. M386685.

Figure 2B is the APC circuit diagram using Taiwan Patent No. M386685.

Figure 3 is a circuit diagram of the conventional LD automatic power control.

Figure 4A is a schematic diagram of the structure of a preferred embodiment of the present invention.

Figure 4B is a structural cross-sectional view of a preferred embodiment of the present invention.

Figure 5 is a circuit diagram of a preferred embodiment of this invention.

Figure 6 is a schematic diagram of the adjustment circuit of the preferred embodiment of this invention.

Figure 7 is a schematic diagram of automatic power writing (APW) of a preferred embodiment of the present invention.

The following is a specific implementation example to illustrate the implementation of this creation. People familiar with this art can easily understand the other advantages and effects of this creation from the content disclosed in this manual. This creation can also be implemented or applied through other different specific implementation examples. The details in this manual can also be modified and changed based on different viewpoints and applications without deviating from the spirit of this creation.

First, please refer to Figures 4A to 7. The automatic power writing light spot emitter 60 of the present invention includes a preferred embodiment: a base 10, which is a heat sink type. In this embodiment, the base 10 is configured as a lead frame type structure of a TO-CAN package, on which a first pin P1, a second pin P2, and a third pin P3 are provided, and the first and second pins P1 and P2 are respectively connected to the positive and negative power sources. In this embodiment, the first pin P1 is a voltage supply terminal (VCC), and the second pin P2 is a ground terminal (GND).

As shown in FIG. 4A and FIG. 4B, a laser diode (LD) 30 is disposed on a submount 20 of the base 10, and a photodiode (PD) 40 is located on the light-emitting surface of the laser diode 30 to detect the laser power; in this embodiment, the TO-CAN package schematic diagram further includes a metal cover 11 to package and protect the laser diode (LD) 30 and the photodiode (PD) 40 inside, and the light of the laser diode is output through the coated glass 12, and the packaged components are fixed and heat is dissipated on the base 10. However, the above-mentioned structure belongs to the prior art, which is not the patent subject of this creation, and it is not necessary to elaborate.

The main features of this invention are: an automatic power writing circuit (APW IC) 50, which is configured as a circuit board or IC structure and directly disposed on the base 10 to control the laser power; and the photodetector diode (PD) 40 is disposed on the automatic power writing circuit 50.

As shown in FIG. 5 , in this embodiment, the automatic power writing circuit 50 includes: the first pin P1 is coupled in series with the photodetector diode 40, and is coupled in parallel with a first anti-static protection circuit 51a, and the first anti-static protection circuit (ESD1) 51a is coupled in parallel with a ground terminal (GND); a logic circuit 52 is coupled between the first pin P1 and the third pin P3 respectively; an error amplifier 53 is coupled in parallel with the photodetector diode 40, responsible for the loop and determines the current of the laser diode 30.

A protection circuit 54 is composed of a reference voltage (Vref) and a low voltage lock circuit (UVLO), which are respectively connected to the input and output terminals of the error amplifier 53, as a reference voltage and to prevent low voltage malfunction; in this embodiment, the protection circuit 54 may include but is not limited to: an over current protection, an over temperature protection, a short circuit protection, and a reverse voltage protection, etc., which are not elaborated.

A transistor (MD) 55 is serially coupled to the error amplifier 53, an output contact (LDo) 56 of the laser diode 30 and the ground terminal (GND); a current monitoring circuit (OCP) 57 is parallel connected to the transistor 55 and coupled to the ground terminal (GND).

A PWM control 58 is connected to the third pin P3 and coupled between the error amplifier 53 and the transistor 55, and is used for writing functions to set the laser output power and PWM to adjust the laser rate.

A trimming circuit 59 is connected to the photodiode 40 and the ground terminal (GND). The trimming circuit 59 changes the resistance value of a resistor ( _RA ) according to a trimming code (TRC). As shown in FIG6 , the trimming circuit 59 connects a plurality of switches (SW1), (SW2) to (SWn) at a plurality of joints of the resistor ( _RA ). The trimming circuit 59 selectively turns on the switches (SW1) to (SWn) according to the trimming code (TRC) to short-circuit a portion of the resistor ( _RA ), thereby changing the resistance value. In this embodiment, a decoder 591 output is used to select different resistance values for writing, and the writing pin is the same as the PWM control 58, which is the third pin P3. In addition, when the logic circuit 52 is powered, based on the setting information stored in the memory, the trim code TRC is output to the resistor ( _RA ).

In this way, the light detection diode 40 detects the optical power value of the laser diode 30, notifies the optical power change in the form of circuit feedback and makes current compensation in real time, so that the optical power can be stably maintained at the power value written in the automatic power writing circuit (APW IC) 50.

In addition, in this embodiment, the automatic power writing circuit 50 may further include: a second anti-static protection circuit (ESD2) 51b, which is provided between the laser diode output contact (LDo) 56 and the ground terminal (GND), and a third anti-static protection circuit (ESD3) 51c, which is connected in parallel between the third pin P3 and the ground terminal (GND). Furthermore, the automatic power writing circuit 50 may further include a slow start circuit 501 to prevent overcurrent during startup, and a unidirectional diode 502 is provided between the first pin P1 and the photodetector 40.

As mentioned above, the automatic power writing light spot emitter 60 of this invention is a three-pin structure of the automatic power writing circuit (APW IC) 50 with the TO-CAN package. In this way, the IC is designed to achieve the functions of loop control compensation and circuit protection. The three pins that can be connected to the TO-CAN are divided into three types: VCC, GND, and PWM (as shown in Figure 4A). The positive and negative ends of the general power supply VCC (+) and GND (-) are necessary pins. The remaining third pin P3 is designed to be a pin that can write light power. After the writing is completed, it can become a function of controlling the light signal with PWM. Therefore, the third pin P3 has two functions: "write function as setting laser output power" and "PWM adjustment of laser power".

It is not difficult to write to an IC, but to write light power with a laser diode on the limited three pins and to control the light power change with a PWM signal, you must carefully consider how to design it to achieve this function. Therefore, this creation first preliminarily designs a conceptual architecture diagram (as shown in Figure 6). The circuit concept is mainly based on the photocurrent value generated by the backlight (Backlight) generated by the light-emitting diode (LD) 30 shining on the photodetector diode (PD) 40, and the error amplifier (EA) 53 loops to determine the current value provided to the laser diode (LD) 30, and writes through the resistance value selected by the decoder 591.

After the resistance value is written, the APW light spot emitter 60 will provide a fixed current value to the laser diode (LD) 30 when it is driven, and generate a fixed output optical power at the same time, but the pin for writing the resistance value has no other function. In order to further improve the design of the automatic power writing (APW), the invention connects the third pin P3 to the PWM control block, so that the APW light spot emitter 60 can use the PWM signal to modulate the optical power, and become an adjustable PWM optical signal.

FIG7 discloses a schematic diagram of the automatic power writing (APW) of the decoder 591 used in the present invention, and the process is as follows: (a). The trim code is written through the PWM pin (the third pin P3); (b). According to the write pulse pattern → to set the E-Fuse state ("H" or "L") → to store in the register; (c). Decoding is performed according to the register data.

Based on the above structure, the adjustment circuit 59 shown in the blocks shown in Figures 5 to 7 uses the output of the decoder 591 to select different resistance values for writing. Since the write pin is the same pin as the PWM (the third pin P3), a special mode must be set to achieve the trim code TRC writing condition. After the writing is completed, it becomes a PWM function pin to control the PWM signal of the laser diode.

Therefore, the APW (Auto Power Write) design of this invention maintains the original three-pin structure of the TO-CAN package type, but can additionally write the code into the APW IC, so that the laser can directly reach the target optical power value after being driven and can maintain it. After the IC is written, this third pin P3 can become the control pin of the PWM signal. As long as the PWM signal is provided, the output optical signal of the laser can also produce a synchronous PWM effect.

With the help of the above-mentioned technical means, this invention is to match the photodetector diode (PD) 40 and APW (Auto Power Write) IC inside the TO-CAN package. This design architecture can use the photodetector diode (PD) 40 to detect the optical power value of the laser diode (LD) 30, and use the circuit feedback to notify the optical power change and make current compensation in real time, so that the optical power can be stably maintained at the power value written by the APWIC; at the same time, the IC is designed with safety protection such as protection circuits, so that users can safely control the laser diode. This package is packaged in a single TO-CAN to achieve the goal of small size and low cost.

In summary, the technical means revealed by this creation do meet the patent requirements of "novelty", "progressiveness" and "availability for industrial use". I pray that the Bureau of Industry will grant the patent to encourage creation without any sense of gratitude.

However, the above disclosed diagrams and descriptions are only the best embodiments of this creation. Any modifications or equivalent changes made by those familiar with this technology in accordance with the spirit of this case should still be included in the scope of the patent application of this case.

30: Laser diode

40: Photodetector diode

50: Automatic power writing circuit

501: Soft start circuit

502: One-way diode

51a: The first anti-static protection circuit

51b: Second anti-static protection circuit

51c: The third anti-static protection circuit

52:Logic circuit

53: Error amplifier

54: Protection circuit

55: Transistor

56: Laser diode output contact

57: Current monitoring circuit

58:PWM control

59: Adjust the circuit

P1: First pin

P2: Second pin

P3: Third pin

Claims (6)

An automatic power writing light spot emitter comprises: a base, the base is set as a lead frame structure of a TO-CAN package, a first pin, a second pin, and a third pin are arranged on the base, and the first and second pins are connected to a positive power source and a negative power source respectively; a laser diode is arranged on a primary fixing seat of the base; a photodetector diode is located on the light emitting surface of the laser diode for detecting laser power; its characteristics are: an automatic power writing circuit (APW IC), the automatic power writing circuit is configured as a circuit board or an IC structure, and is directly configured on the base to control the laser power; the photodetector diode is configured on the automatic power writing circuit; the automatic power writing circuit comprises: the first pin is coupled in series with the photodetector diode, and is coupled in parallel with a first antistatic protection circuit, and the first antistatic protection circuit is coupled in parallel with a ground terminal; a logic circuit is coupled between the first pin and the third pin respectively; an error amplifier is coupled in parallel with the photodetector diode, responsible for the loop and determining the laser diode current; a protection circuit connected to the error amplifier as a reference voltage and to prevent low voltage malfunction; a transistor coupled in series to the error amplifier, an output contact of the laser diode and the ground terminal; a current monitoring circuit connected in parallel to the transistor and coupled to the ground terminal; a PWM control connected to the third pin and coupled between the error amplifier and the transistor for writing functions to set the laser output power and PWM to adjust the laser rate; and an adjustment circuit connected to the photodetector diode and the ground terminal, the adjustment circuit adjusting the laser output power according to an adjustment code (Trim The invention discloses a method for changing the resistance value of a resistor ( _RA ) by using a decoder output to select different resistance values for writing, and the writing pin is the same as the PWM control pin, thereby detecting the optical power value of the laser diode with the photodiode, notifying the optical power change in the form of circuit feedback and making current compensation in real time, so that the optical power can be stably maintained at the power value written by the automatic power writing circuit (APW IC). As described in item 1 of the patent application scope, the automatic power writing light spot emitter, wherein the adjustment circuit connects a plurality of switches (SW1), switch (SW2) to switch (SWn) at multiple joint positions of the resistor, and selectively turns on the switches (SW1) to (SWn) according to the adjustment code (TRC), thereby short-circuiting a portion of the resistor ( _RA ), thereby changing the resistance value. As described in the first item of the patent application scope, the automatic power writing light spot emitter, wherein the automatic power writing circuit further includes a second anti-static protection circuit, which is arranged between an output contact of the laser diode and the ground terminal; and a third anti-static protection circuit, which is connected in parallel between the third pin and the ground terminal. As described in the first item of the patent application scope, the automatic power writing light spot emitter, wherein the automatic power writing circuit further includes a slow start circuit to prevent overcurrent during startup, and a one-way diode is provided between the first pin and the photodetector diode. As described in the first item of the patent application scope, the automatic power writing light spot emitter, wherein the base further includes a metal cover and a coated glass. As described in the first item of the patent application scope, the automatic power writing light spot emitter, wherein the protection circuit includes: an over current protection, an over temperature protection, a short circuit protection, and a reverse voltage protection.

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