Non-Final Rejection
The present application is being examined under the pre-AIA first to invent provisions. Claims 1-21 are pending.
Drawings
Figure 1 should be designated by a legend such as --Prior Art-- because only that which is old is illustrated. See MPEP § 608.02(g). The specification quite clearly calls this prior art. Corrected drawings in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. The replacement sheet(s) should be labeled “Replacement Sheet” in the page header (as per 37 CFR 1.84(c)) so as not to obstruct any portion of the drawing figures. If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-7 and 14-21 are rejected under 35 U.S.C. 103 as being unpatentable over US 2024/0266800 (“Arulandu”) in view of US 2024/0275130 (“Piskunov”).
1. An automatic power control circuit, comprising:
Arulandu describes a circuit for controlling the output power of a laser at a constant level over various operating conditions using feedback. [0004], [0021], Fig. 3 and discussion. A person of ordinary skill would recognize this as an automatic power control circuit.
a voltage measurement unit configured to obtain an indicative voltage at a specific measurement point and output the indicative voltage, wherein the indicative voltage is configured to indicate a forward voltage of a laser diode in laser emitting state; and
Arulandu maintains a constant laser power by recognizing that output changes based on the temperature of the laser, and thus changes the drive current depending on the junction temperature. [0003]-[0004], [0006]-[0014], [0053]-[0058]. Arulandu gives a few examples for determining the junction temperature. One can use a thermistor, [0065], or one can use a photodiode, [0066]. Arulandu does not disclose a voltage measuring unit as claimed. Piskunov teaches a circuit for controlling power of a laser diode, and in Fig. 1 shows voltage sensor SV that senses the voltage of the laser diode and provides signal VLD indicative of that voltage, and uses this in part for estimating the junction temperature of the laser diode. [0045]. It would have been obvious to a person of ordinary skill in the art to use such a voltage measurement unit as a simple substitution of one known element for another to yield predictable results. MPEP 2143 I.B. Arulandu does things to determine junction temperature but not a voltage measurement unit; Piskunov uses a voltage measurement unit to determine junction temperature. A person of ordinary skill could have used Piskunov’s voltage measurement unit in place of Arulandu’s ways and the result of the substitution would have been predictable. Both of them are doing the same thing, determining a junction temperature, and Arulandu itself is open to a couple different ways of doing it, i.e. it is not tied to any one particular way. Determining the temperature in a different way will ultimately yield the same result and temperature will be useable to control power just as it is already done in Arulandu.
a processor configured to output a pulse parameter control signal in response to the indicative voltage, wherein the pulse parameter control signal is used to control an adjustment for a pulse parameter of laser pulses of the laser diode, such that laser emission power is within a preset range, and
Controller 106 of Arulandu outputs pulse parameters, the amplitude and duty cycle of a PWM drive current, depending on the junction temperature. [0064], [0073]. Following the combination the temperature is determined in response to the voltage so the controller is likewise in response to the voltage. The pulse parameters are adjusted—things like duty cycle and amplitude of the driver current are changed, so that the pulse output power is constant, i.e. within a preset range. [0059]-[0062]. A person of ordinary skill would understand the pulsed drive current causes and directly impacts the laser pulses.
wherein the pulse parameter of the laser pulses of the laser diode is used to set a total duration of pulses within a preset time period.
As seen in Fig. 2, [0059]-[0062], the duration of the pulses is set over a period of time, depending on the temperature. For example plot 30 at 25 degrees C has a shorter duration but higher amplitude, while plot 40 at 60 degrees has a longer duration. The skilled artisan can use these graphs to “set” the total duration of laser pulses over the time period with which they are interested. That is, they will know at higher temperatures they need the higher duration.
Regarding claim 2, there is a power control unit that controls current source 104 and switching element 108 to control and adjust the pulses. [0064].
Regarding claim 3, Arulandu explicitly says duty cycle is changed to maintain constant power. [0061].
Regarding claims 4-5, Arulandu uses pulse width modulation to alter and control the power. However, the examiner takes official notice that pulse number modulation, changing the number of pulses over a time period, is also well known in the art and is used with or in alternative to pulse width modulation. It would have been obvious to a person of ordinary skill in the art as another equivalent means of controlling the power. A person skilled in the art would understand that more pulses means more power and less pulses less power. The skilled artisan would therefore likewise reduce pulses when the laser voltage is higher and increase pulses when voltage is lower.
Regarding claim 6, again the total duration of pulses is set by setting the duty cycle. Fig. 2, [0061].
Regarding claim 7, like with claims 4 and 5 above the number of pulses may be adjusted to control the power. By definition we can call the total duration of pulses equal to a product of the number of pulses and a pulse duration of each laser pulse, and the effective drive current is equal to a difference between a drive current flowing through the laser diode and a threshold current of the laser diode. The purpose of Arulandu is to maintain constant power, so we can say the product of the total duration of pulses and an effective drive current is within a preset threshold interval.
Regarding claim 14, the photodiode of Arulandu is clearly optional (used “alternatively” in [0066]) and is used only for measuring temperature, which was replaced by the voltage measuring unit in the rejection of claim 1. The APC therefore is not provided with a photodiode.
Regarding claim 15, the claim is a method claim but all of the steps are also found in claim 1 and are met as in the rejection of claim 1.
Regarding claims 16-19, see the rejection of claims 3, 6, 4, and 5 above, respectively.
Regarding claim 20, current source 104 can be considered a setting value of drive current that is set even before pulses are emitted, and the pulse parameter is adjusted by doing the PWM using the switching element. [0064].
Regarding claim 21, the claim is the same as claim 1 except it is a “laser diode circuit” and positively recites “a laser diode configured to emit laser pulses.” Arulandu is such a circuit for controlling laser diodes, [0028]-[0029], and pulses are produced as discussed re: claim 1.
Claims 12-13 are rejected under 35 U.S.C. 103 as being unpatentable over Arulandu and Piskunov as applied to claim 1, and further in view of US 2010/0158057 (“Lerner”).
Regarding claims 12-13, Piskunov’s voltage measuring unit is connected to the measuring point, at the cathode of the laser diode, and again the controller of Arulandu would determine the voltage based on the sensed signal. It is not disclosed that this is an analog sensor sensing an analog signal and there is an ADC converting the analog signal to a digital signal to go to the processor.
Lerner teaches that a laser driver can have analog sensors, see 211A-C, and can have ADC 214 for changing the analog measurement to digital before being used by the processor. Fig. 2, [0033]-[0036]. It would have been obvious to a person of ordinary skill in the art that analog sensors could be used. Piskunov does not specify, analog sensors are clearly known, and analog sensors have different pros and cons than digital ones (e.g. more continuous measurement, higher resolution measurement), so it would have been obvious to a person of ordinary skill in the art to use analog in a situation where such pros would be preferred. And of course, a processor will deal in digital signals so it would have been obvious to a person of ordinary skill in the art to include the ADC to convert to digital before sending to the controller.
Allowable Subject Matter
Claims 8-11 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
Regarding claim 8, there is not taught or disclosed in the prior art the automatic power control circuit of claim 2, including the particular claimed structure for controlling the current to the laser to control duration of pulses. Claims 9-11 depend from claim 8.
Pertinent Art
US 2004/0109482 indicates that it is conventional to control power based on number of pulses.
US 4,831,626 in description of prior art shows it was known to control power of a pulsed laser beam by controlling the number or the width of the pulses.
US 2015/0155686 has automatic power control based on voltage of a laser driver.
US 2020/0036157 has automatic power control based on part on voltage of a laser.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to James Menefee whose telephone number is (571)272-1944. The examiner can normally be reached M-F 7-4.
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/JAMES A MENEFEE/ Primary Examiner, Art Unit 2828