DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
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.
Claim(s) 1, 2, 3, 8, 10, 11, 12, 13, 14, 18 and 19 is/are rejected under 35 U.S.C. 103 as being unpatentable over Knapp et al. (9,578,724) in view of Stevens (2012/0299481).
Regarding claim 1, Knapp teaches a light-emitting device, comprising: a light-emitting diode (col 5, lines 30-33: an illumination device is provided herein with a plurality of light emitting diode (LED) chains,); and a control circuit (col 5, lines 30-33: an illumination device is provided herein with a plurality of light emitting diode (LED) chains, a driver circuit, a storage medium and a control circuit.) coupled to the light-emitting diode, and configured to control the light-emitting diode to provide an output light during a first period (col 5, lines 38-40: The driver circuit may be generally configured for driving the plurality of LED chains with drive currents substantially continuously to produce illumination, ; Fig 5, step 30; col 14, lines 57-61: As shown in FIGS. 5 and 7, the plurality of LEDS are driven substantially continuously with operative drive current levels (denoted generically as I1 in FIG. 7) to produce illumination (in step 30 of FIG. 5).) and provide a detection signal to the light-emitting diode to receive a sensing voltage value of the light-emitting diode during a second period (Fig 5. Step 32+34; col 14, line 61 to col 15, line 3: At periodic intervals, the plurality of LEDs are turned off for short durations of time (in step 32 of FIG. 5) by removing the drive currents, or at least reducing the drive currents to non-operative levels (denoted generically as I0 in FIG. 7). During each periodic interval in which the plurality of LEDs are turned off, one LED is driven with a relatively small, non-operative drive current (e.g., approximately 0.1-10 mA, not shown in FIG. 7) and the operating forward voltage developed across that LED is measured (e.g., Vf1, Vf2, Vf3 or Vf4)), wherein the first period and the second period alternate and do not overlap with each other (Fig 8), and wherein the control circuit obtains a forward voltage of the light-emitting diode according to the sensing voltage value (col 14, line 67-col 15, line 4 : non-operative drive current (e.g., approximately 0.1-10 mA, not shown in FIG. 7) and the operating forward voltage developed across that LED is measured (e.g., Vf1, Vf2, Vf3 or Vf4). The forward voltage is measured across each LED, one LED at a time), and compensates the output light according to the junction temperature (col 15, lines 15-19: Once the operating forward voltage (Vfx) is measured from each LED, the compensation method shown in FIG. 5 determines the drive current (Ix) needed to achieve a desired luminous flux (Lx) from each LED using the operating forward voltages). Knapp also further teaches, it is generally well known that the forward voltage of an LED changes linearly with junction temperature when a fixed forward-biased drive current is supplied to the LED. FIG. 14 demonstrates the linear relationship between forward voltage and junction temperature with the forward voltages normalized to ‘1’ at 25° C. (roughly room temperature). As shown in FIG. 14, the forward voltage developed across the LED junction decreases linearly as the junction temperature increases (and vice versa). As a consequence, LED forward voltages measured at a fixed drive current can be used to provide a fairly precise estimate of junction temperature for a particular LED (Knapp: col 2, lines 56-67).
Knapp fails to explicitly teach, wherein the control circuit obtains a junction temperature of the light-emitting diode according to the sensing voltage value, and compensates the output light according to the junction temperature; as claimed.
Stevens teaches a light-emitting device, comprising: a light-emitting diode (610; Fig 6); and a control circuit (other portion of circuit of Fig 6) coupled to the light-emitting diode, and wherein the control circuit obtains a junction temperature of the light-emitting diode according to a sensing voltage value (para [0032] to determine the junction temperature of the LED(s) 610 at any given time, the power 614 to the LED(s) 610 is temporarily disconnected and a constant current 616 is applied to the LED(s) 610 for a short time duration t; the time duration t is sufficient for measuring the voltage across the LEDs 610), and compensates the output light according to the junction temperature (para [0033] The measured voltage is then processed by the controller 618 to calculate the junction temperature and, based thereon, an operational current and temperature that optimizes the performance and lifetime of the LED can be calculated by the controller 618. Values for the optimal load current and the associated temperature are sent to the LED power controller 622 and appropriate actions can be taken--e.g., adjustment of the load current and the associated temperature to optimize the lifetime of the LED or shutdown the circuit due to overheating or any other fault conditions. In one embodiment, the thermometer 600 includes a detecting sensor 626; upon detecting a luminous intensity of light in the environment below a predetermined threshold, the sensor transmits a signal to the controller 618, automatically triggering a larger load current to flow through the LEDs 610, thus increasing the brightness of the LEDs 610.).
It would have been obvious to one of ordinary skill in the art before the filing date of present application to have modified the device of Knapp with teachings of Stevens, because this will provide systems and methods based on this approach provide a fast, easily implemented, and inexpensive way to directly measure the actual junction temperature of the LEDs and optimize the performance and lifetime of the LEDs. (Stevens: para [0033]).
Regarding claim 2, Knapp teaches the light-emitting device according to claim 1, wherein the control circuit comprises: a lookup table configured to record a plurality of forward voltage corresponding to a plurality of sensing voltage values (Fig 4); and a controller coupled to the lookup table and configured to obtain the forward voltage by using the lookup table and the received sensing voltage value (col 13, lines 33-44: the forward voltage and luminous flux values measured during steps 12, 14, 18 and 24 may be stored within the illumination device in step 22 of the calibration method of FIG. 1. In one embodiment, the calibration values may be stored within a table of calibration values, as shown for example in FIG. 4. The stored calibration values may then be used in the compensation method of FIG. 5 (discussed below) to adjust or maintain the luminous flux output from each individual LED. If the illumination device comprises multiple colors of LEDs, the stored calibration values may also be used to adjust or maintain the color point of the illumination device.).
Knapp fails to teach, a junction temperature lookup table; as claimed.
However, given prior art Knapp teaches the relationship between forward voltage and junction temperature; it would have been obvious to one of ordinary skill in the art before the filing date of present application to have modified the device of Knapp to provide a junction temperature lookup table configured to record a plurality of junction temperatures corresponding to a plurality of sensing voltage values; and a controller coupled to the junction temperature lookup table and configured to obtain the junction temperature by using the junction temperature lookup table and the received sensing voltage value; in order to yield predictable results.
Regarding claim 3, Knapp teaches the light-emitting device according to claim 2, wherein the control circuit controls the light-emitting diode to provide the output light by using a driving signal (col 16, lines 55-64: The selected drive current may then be used to drive the LED to produce illumination having the desired luminous flux (in step 38 of FIG. 5).), and the control circuit adjusts a duty cycle of the driving signal according to the junction temperature (col 2, lines 56-58: it is generally well known that the forward voltage of an LED changes linearly with junction temperature ; col 16, lines 55-64: The selected drive current may then be used to drive the LED to produce illumination having the desired luminous flux (in step 38 of FIG. 5). This process is then repeated for each of the plurality of LEDs, until each is configured for producing a desired luminous flux at the present operating temperature. The drive currents supplied to the LEDs may be adjusted to meet the selected drive currents either by adjusting the drive current level (i.e., current dimming), or by changing the duty cycle of the drive current through Pulse Width Modulation (PWM) dimming.).
Regarding claim 8, Knapp teaches the light-emitting device according to claim 3, wherein the control circuit receives a control signal and generates the driving signal according to the control signal (col 15, lines 15-36: Once the operating forward voltage (Vfx) is measured from each LED, the compensation method shown in FIG. 5 determines the drive current (Ix) needed to achieve a desired luminous flux (Lx) from each LED using the operating forward voltages, the table of stored calibration values generated during the calibration method of FIG. 1 and one or more interpolation techniques (in step 36 of FIG. 5). For example, the compensation method may calculate a luminous flux value for the present forward voltage/operating temperature at each of the previously calibrated drive current levels by interpolating between the stored calibration values. Once a luminous flux value is calculated at each of the previously calibrated (i.e., known) drive current levels, another interpolation technique may be used to determine an unknown drive current needed to produce a desired luminous flux, should the desired luminous flux differ from one of the calculated luminous flux values. FIG. 6 is a graphical illustration depicting how one or more interpolation technique(s) may be used to determine the drive current needed to produce a desired luminous flux from the stored calibration values.).
Regarding claim 10, Knapp teaches the light-emitting device according to claim 1, wherein the detection signal is a detection current signal (col 14, lines 15-16: By using non-operative drive currents to obtain the forward voltage calibration values,).
Regarding claim 11, Knapp teaches the light-emitting device according to claim 1, wherein the control circuit comprises: a current source (62; Fig 11) coupled to the light-emitting diode and configured to provide the detection signal during the second period (col 24, lines 10-15: While the current source 62 connected to this LED chain should remain on, the drive current (Idr) should be switched from the operating current level (e.g., about 20 mA to about 500 mA) to the relatively small drive current level used to take forward voltage measurements (e.g., about 0.1 mA-10 mA).).
Regarding claim 12, Knapp teaches the light-emitting device according to claim 1, wherein a time length of the second period is shorter than a time length of the first period (col 14, lines 42-49: the compensation method shown in FIG. 5 may begin by driving the plurality of LEDs substantially continuously to produce illumination (in step 30). As used herein, the term “substantially continuously” means that an operative drive current is supplied to the plurality of LEDs almost continuously, with the exception of periodic intervals during which the plurality of LEDs are momentarily turned off for short durations of time (in step 32). Col 14, line 61 to Col 15 : line 3: At periodic intervals, the plurality of LEDs are turned off for short durations of time (in step 32 of FIG. 5) by removing the drive currents, or at least reducing the drive currents to non-operative levels (denoted generically as I0 in FIG. 7). During each periodic interval in which the plurality of LEDs are turned off, one LED is driven with a relatively small, non-operative drive current (e.g., approximately 0.1-10 mA, not shown in FIG. 7) and the operating forward voltage developed across that LED is measured (e.g., Vf1, Vf2, Vf3 or Vf4).).
Regarding claim 13, Knapp teaches an operating method for a light-emitting device, wherein the light emitting device comprises a light-emitting diode (col 5, lines 30-33: an illumination device is provided herein with a plurality of light emitting diode (LED) chains,); and the operating method comprises: controlling the light-emitting diode to provide an output light during a first period (col 5, lines 38-40: The driver circuit may be generally configured for driving the plurality of LED chains with drive currents substantially continuously to produce illumination, ; Fig 5, step 30; col 14, lines 57-61: As shown in FIGS. 5 and 7, the plurality of LEDS are driven substantially continuously with operative drive current levels (denoted generically as I1 in FIG. 7) to produce illumination (in step 30 of FIG. 5).); providing a detection signal to the light-emitting diode to receive a sensing voltage value of the light-emitting diode during a second period (Fig 5. Step 32+34; col 14, line 61 to col 15, line 3: At periodic intervals, the plurality of LEDs are turned off for short durations of time (in step 32 of FIG. 5) by removing the drive currents, or at least reducing the drive currents to non-operative levels (denoted generically as I0 in FIG. 7). During each periodic interval in which the plurality of LEDs are turned off, one LED is driven with a relatively small, non-operative drive current (e.g., approximately 0.1-10 mA, not shown in FIG. 7) and the operating forward voltage developed across that LED is measured (e.g., Vf1, Vf2, Vf3 or Vf4)), wherein the first period and the second period alternate and do not overlap with each other (Fig 8), and obtaining a forward voltage of the light-emitting diode according to the sensing voltage value (col 14, line 67-col 15, line 4 : non-operative drive current (e.g., approximately 0.1-10 mA, not shown in FIG. 7) and the operating forward voltage developed across that LED is measured (e.g., Vf1, Vf2, Vf3 or Vf4). The forward voltage is measured across each LED, one LED at a time), and compensating the output light according to the junction temperature (col 15, lines 15-19: Once the operating forward voltage (Vfx) is measured from each LED, the compensation method shown in FIG. 5 determines the drive current (Ix) needed to achieve a desired luminous flux (Lx) from each LED using the operating forward voltages). Knapp also further teaches, it is generally well known that the forward voltage of an LED changes linearly with junction temperature when a fixed forward-biased drive current is supplied to the LED. FIG. 14 demonstrates the linear relationship between forward voltage and junction temperature with the forward voltages normalized to ‘1’ at 25° C. (roughly room temperature). As shown in FIG. 14, the forward voltage developed across the LED junction decreases linearly as the junction temperature increases (and vice versa). As a consequence, LED forward voltages measured at a fixed drive current can be used to provide a fairly precise estimate of junction temperature for a particular LED (Knapp: col 2, lines 56-67).
Knapp fails to explicitly teach, obtaining a junction temperature of the light-emitting diode according to the sensing voltage value, and compensating the output light according to the junction temperature; as claimed.
Stevens teaches an operating method for a light-emitting device comprising: a light-emitting diode (610; Fig 6); and obtaining a junction temperature of the light-emitting diode according to a sensing voltage value (para [0032] to determine the junction temperature of the LED(s) 610 at any given time, the power 614 to the LED(s) 610 is temporarily disconnected and a constant current 616 is applied to the LED(s) 610 for a short time duration t; the time duration t is sufficient for measuring the voltage across the LEDs 610), and compensating the output light according to the junction temperature (para [0033] The measured voltage is then processed by the controller 618 to calculate the junction temperature and, based thereon, an operational current and temperature that optimizes the performance and lifetime of the LED can be calculated by the controller 618. Values for the optimal load current and the associated temperature are sent to the LED power controller 622 and appropriate actions can be taken--e.g., adjustment of the load current and the associated temperature to optimize the lifetime of the LED or shutdown the circuit due to overheating or any other fault conditions. In one embodiment, the thermometer 600 includes a detecting sensor 626; upon detecting a luminous intensity of light in the environment below a predetermined threshold, the sensor transmits a signal to the controller 618, automatically triggering a larger load current to flow through the LEDs 610, thus increasing the brightness of the LEDs 610.).
It would have been obvious to one of ordinary skill in the art before the filing date of present application to have modified the method of Knapp with teachings of Stevens, because this will provide systems and methods based on this approach provide a fast, easily implemented, and inexpensive way to directly measure the actual junction temperature of the LEDs and optimize the performance and lifetime of the LEDs. (Stevens: para [0033]).
Regarding claim 14, Knapp teaches the operating method according to claim 13, wherein the step of compensating the output light according to the junction temperature comprises: adjusting a duty cycle of a driving signal according to the junction temperature (col 2, lines 56-58: it is generally well known that the forward voltage of an LED changes linearly with junction temperature ; col 16, lines 55-64: The selected drive current may then be used to drive the LED to produce illumination having the desired luminous flux (in step 38 of FIG. 5). This process is then repeated for each of the plurality of LEDs, until each is configured for producing a desired luminous flux at the present operating temperature. The drive currents supplied to the LEDs may be adjusted to meet the selected drive currents either by adjusting the drive current level (i.e., current dimming), or by changing the duty cycle of the drive current through Pulse Width Modulation (PWM) dimming.); and controlling the light-emitting diode to provide the output light by using the driving signal (col 16, lines 55-64: The selected drive current may then be used to drive the LED to produce illumination having the desired luminous flux (in step 38 of FIG. 5).).
Regarding claim 18, Knapp teaches the operating method according to claim 13, wherein the detection signal is a detection current signal (col 14, lines 15-16: By using non-operative drive currents to obtain the forward voltage calibration values,).
Regarding claim 19, Knapp teaches the operating method according to claim 13, wherein a time length of the second period is shorter than a time length of the first period (col 14, lines 42-49: the compensation method shown in FIG. 5 may begin by driving the plurality of LEDs substantially continuously to produce illumination (in step 30). As used herein, the term “substantially continuously” means that an operative drive current is supplied to the plurality of LEDs almost continuously, with the exception of periodic intervals during which the plurality of LEDs are momentarily turned off for short durations of time (in step 32). Col 14, line 61 to Col 15 : line 3: At periodic intervals, the plurality of LEDs are turned off for short durations of time (in step 32 of FIG. 5) by removing the drive currents, or at least reducing the drive currents to non-operative levels (denoted generically as I0 in FIG. 7). During each periodic interval in which the plurality of LEDs are turned off, one LED is driven with a relatively small, non-operative drive current (e.g., approximately 0.1-10 mA, not shown in FIG. 7) and the operating forward voltage developed across that LED is measured (e.g., Vf1, Vf2, Vf3 or Vf4).).
Allowable Subject Matter
Claims 4-7, 9 and 15-17 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.
The following is a statement of reasons for the indication of allowable subject matter: Regarding claim 4, prior art of record fails to teach the following claim limitations of “wherein the control circuit determines whether the light-emitting diode provides the output light lower than set brightness during the first period according to the driving signal, and when it is determined that the output light lower than the set brightness is provided during the first period, the control circuit stops providing the detection signal during the second period after the first period during which the output light lower than the set brightness is provided.”; in combination with all other claim limitations. Regarding claim 5, prior art of record fails to teach the following claim limitations of “a compensation value lookup table coupled to the controller and configured to record a plurality of compensation values corresponding to the junction temperatures, wherein the controller obtains a compensation value corresponding to the current junction temperature by using the compensation value lookup table, and controls the driving circuit according to the compensation value, and wherein the driving circuit adjusts the duty cycle of the driving signal according to the compensation value.”; in combination with all other claim limitations. Regarding claim 9, prior art of record fails to teach the following claim limitations of “…and the control circuit decodes the data signal by using the clock signal to generate the driving signal.”; in combination with all other claim limitations. Regarding claim 15, prior art of record fails to teach the following claim limitations of “determining whether the light-emitting diode provides the output light lower than set brightness during the first period according to the driving signal; and when it is determined that the output light lower than the set brightness is provided during the first period, the detection signal is stopped from being provided during the second period after the first period during which the output light lower than the set brightness is provided.”; in combination with all other claim limitations. Regarding claim 16, prior art of record fails to teach the following claim limitations of “wherein when the junction temperature of the light-emitting diode is equal to a reference temperature, the light-emitting diode provides a reference output light having reference brightness, and the step of adjusting the duty cycle of the driving signal according to the junction temperature comprises: obtaining a brightness ratio of brightness of the output light and the reference brightness according to the junction temperature, and obtaining a compensation value according to the brightness ratio; and adjusting the duty cycle of the driving signal according to the compensation value.”; in combination with all other claim limitations.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Hoogzaad et al. (2010/0315019) teaches A driver circuit (10) for a light emitting diode comprises a first driver circuit (32, 32', 32') for generating a first current output for driving the light emitting diode, wherein the first driver circuit has a control switch for interrupting the supply of the first current output. A second driver circuit (50) is for generating a second current output for driving the light emitting diode, and the second driver circuit also has a control switch for interrupting the supply of the second current output.
Ho et al. (9,155,155) teaches A method and illumination device are provided for interference-resistant compensation in light emitting diode (LED) devices. In one embodiment, the method includes initiating a sequence of measurements during multiple measurement intervals interspersed with periods of illumination.
Domer (8,264,171) teaches LED junction temperature is determined in real time using the LED itself as the temperature sensor for directly measuring the LED junction temperature. In addition, temperature measurements from a silicon diode placed in proximity to the LED are also used to complement the temperature measurements from the LED itself. Arbitration is performed among temperature measurements from the LED and temperature measurements from the silicon diode to determine a temperature of the LED junction. The determined LED junction temperature may be used to make adjustments to the LED drive current.
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/PREMAL R PATEL/Primary Examiner, Art Unit 2624
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