JP6263839B2 - Vehicle lighting - Google Patents

Description

  The present invention relates to a vehicular lamp whose light source is dimmed and extinguished.

  This type of vehicular lamp is conventionally known (for example, Patent Document 1). Hereinafter, a conventional vehicle lamp will be described. A conventional vehicular lamp uses a PWM signal generation unit and a light emission control unit to cause an LED light source to be dimmed and imitated by the falling edge of the bulb light source (that is, bright with a temporal inclination). The lamp is turned off by changing the height).

JP 2009-019945 gazette

  However, the above-described conventional vehicular lamp has a variation in the appearance of the most important lighting immediately before the dimming off due to variations in the characteristics of the components of the light emission control unit.

  The problem to be solved by the present invention is that, in the conventional vehicular lamp, there is a variation in the most important appearance just before turning off the dimming.

The present invention (the invention according to claim 1) is a PWM dimming control circuit, a light source that is dimmed by the PWM dimming control circuit, and connected between the PWM dimming control circuit and the light source. A load lighting circuit that switches on / off of power supply to the light source in accordance with PMW dimming control by the circuit, and the PWM dimming control circuit is a period of PWM dimming control until the light source changes from a lighting state to a light-off state. The load lighting circuit is controlled while changing the duty ratio, which is the ratio of the lighting time of the light source to the light source, so as to decrease with the passage of time, and the duty in the range from at least the first predetermined value to the second predetermined value of the duty ratio The slope of the ratio change is a linear expression, the slope of the duty ratio change equal to or greater than the first predetermined value is a quadratic curve, and the first predetermined value is a duty ratio higher than the second predetermined value. Thus, the range from the first predetermined value to the second predetermined value is equal to, nearly equal to, or larger than the range of variation of the minimum duty ratio that can respond to PWM dimming control in the load lighting circuit. It is characterized by that.

In this invention (the invention according to claim 2), the first predetermined value is the maximum value of the minimum duty ratio in the range of variation, characterized in that.
In the present invention (the invention according to claim 3 ), the second predetermined value is a value lower than the minimum value among the minimum duty ratios in the range of variation .

  In the vehicular lamp according to the present invention, the slope of the duty ratio change between at least the first predetermined value and the second predetermined value of the duty ratio (that is, at least just before extinction (near extinction)) is linear. Therefore, even when the minimum duty ratio that can be responded varies due to variations in the characteristics of the components, the slope of the change in duty ratio is a straight line and constant. Thereby, it is possible to eliminate the variation in the appearance of the most important lighting out of the dimming and to make the appearance of the lighting just before turning off.

FIG. 1 is a configuration block diagram showing Embodiment 1 of a vehicular lamp according to the present invention. FIG. 2 is an explanatory diagram showing variations that occur in the minimum duty ratio that can be responded due to variations in the characteristics of the components. FIG. 3 is an explanatory diagram showing that the slope of the duty ratio change is constant when the slope of the duty ratio change is a straight line. FIG. 4 is an explanatory diagram showing that the slope of the duty ratio change varies when the slope of the duty ratio change is a quadratic curve. FIG. 5 is an explanatory diagram showing variations in the minimum duty ratio that can be responded to due to variations in the characteristics of the components. FIG. 6 is an explanatory diagram of the inclination of the duty ratio change showing the second embodiment of the vehicular lamp according to the present invention.

  Hereinafter, two examples of an embodiment (example) of a vehicular lamp according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. 2, 3, 4, and 6, the vertical axis indicates power output, and the horizontal axis indicates time.

(Description of Embodiment 1)
Hereinafter, the configuration of the vehicular lamp according to the first embodiment will be described. The vehicular lamp according to the first embodiment performs PWM dimming control for the purpose of adjusting the amount of light. As illustrated in FIG. 1, the vehicular lamp according to the first embodiment includes a PWM dimming control circuit 1, a load lighting circuit 2, and a load 3. The vehicular lamp according to the first embodiment performs PWM dimming control for the purpose of adjusting the amount of light.

  The PWM dimming control circuit 1 issues an on / off control instruction to the load lighting circuit 2 connected to the subsequent stage. As shown in FIG. 5A, the instruction is performed by changing the PWM duty ratio (ratio of lighting time or extinguishing time with respect to one cycle. The unit is%) between 0 and 100%. 100% is completely lit, 0% is completely unlit. In the PWM dimming control circuit 1, when the ON / OFF of the power supply itself to the load lighting circuit 2 is set to PWM, the power is always supplied to the load lighting circuit 2, and the load lighting circuit 2 is supplied with power. There is a case where a PWM signal is input to another signal input line.

  As shown in FIGS. 5B and 5C, the load lighting circuit 2 performs ON / OFF of power supply supplied to the load 3 in accordance with the input PWM (see FIG. 5A). . Here, if the load lighting circuit 2 is an ideal load lighting circuit, the input waveform = the output waveform shown in FIG. However, the actual load lighting circuit 2 includes capacitance components (capacitors, semiconductor parasitic capacitances, etc.) and inductance components (coils, wirings, etc.). For this reason, there is a tendency to “dull” with respect to the input waveform. That is, in the region where the duty ratio of the input waveform is small, as shown in FIGS. 5B and 5C, a phenomenon in which output cannot be performed (when tracking cannot be performed) occurs.

  For example, in the case of the load lighting circuit 2 having the characteristic A, as shown in FIGS. 2B and 5B, when the duty ratio is X%, the input from the PWM dimming control circuit 1 is Output is not possible. The minimum duty ratio with which the load lighting circuit 2 having this characteristic A can respond is X%. In the case of the load lighting circuit 2 having the characteristic B, as shown in FIGS. 2C and 5C, when the duty ratio is Y%, the input from the PWM dimming control circuit 1 Output is not possible. The minimum duty ratio with which the load lighting circuit 2 having this characteristic A can respond is Y%.

  The load 3 emits light using electric power (see FIGS. 5B and 5C) supplied from the load lighting circuit 2. The load 3 mainly uses a semiconductor light source (for example, a self-luminous semiconductor light source such as LED, OEL, or OLED (organic EL)), or a light bulb light source (discharge lamp light source such as HID, halogen light source). Incandescent light source) may be used.

  Here, in the vehicular lamp, when the PWM dimming control is performed mainly for the purpose of improving the texture, the duty ratio is set to the time as shown in FIGS. There is a case where the control is performed with the target inclination being lowered (decreasing). In this PWM dimming control, as shown in Patent Document 1, it is common to draw a quadratic curve in which the slope is lowered as the duty ratio decreases in consideration of the visibility characteristic. (See FIG. 4). At this time, the most important point in appearance is the slope immediately before complete extinction (0%) (as a guideline, about 500 ms or less). The larger the slope, the sharper the light is turned off.

  When the load lighting circuit 2 has an ideal characteristic, “output duty ratio of the PWM dimming control circuit 1 (see FIG. 5A) = output duty of the load lighting circuit 2” Ratio (see FIGS. 5B and 5C) = the duty ratio of turning on and off the load 3, and a desired appearance of dimming can be realized.

  However, in the actual load lighting circuit 2, as described above, there is a phenomenon in which output cannot be performed in a region where the duty ratio of the input waveform is small due to the influence of various components. In addition, various components in the actual load lighting circuit 2 do not become constant values for each product due to characteristic variations of parts, temperature characteristics, and the like. For this reason, variation occurs in the minimum duty ratio that can be responded (see X% and Y% in the figure). Due to variations in the minimum duty ratio (X%, Y%) that can be responded, when the slope of the change in the duty ratio is the above-mentioned quadratic curve formula (see FIG. 4), the slope of the duty ratio immediately before the light is turned off is different. For this reason, there are those that turn off smoothly and those that turn off sharply. For example, as shown in FIG. 4, when the minimum duty ratio that can be responded is X%, since the gradient of the duty ratio is small (see A2 in FIG. 4), the light is smoothly turned off. On the other hand, when the minimum duty ratio that can be responded is Y%, the duty ratio has a large gradient (see B2 in FIG. 4), and thus the light is extinguished sharply.

  Here, in the vehicular lamp according to the first embodiment, as shown in FIG. 2 and FIG. 3, as means for aligning the appearance of turning off the load 3 even when the minimum duty ratio that can be responded fluctuates, The vicinity of the extinction of the curve of the quadratic curve equation starting from the time point C (after the time point D) is a linear equation.

  As a result, the vehicular lamp according to the first embodiment can make the appearance of turning off even when the responsive minimum duty ratio varies such as X% and Y%. For example, as shown in FIG. 3, the slope of the duty ratio when the minimum duty ratio that can be responded is X% (see A1 in FIG. 3), and the slope of the duty ratio when the minimum duty ratio that can be responded is Y%. Since it is the same as (refer to B1 in FIG. 3), it is possible to align the appearance of turning off. That is, the appearance of turning off the load 3 that is turned on / off by the output (power supply) from the load lighting circuit 2 having the characteristic A, and the load that is turned on / off by the output (power supply) from the load lighting circuit 2 having the characteristic B The 3 lights off look is complete. As described above, in the vehicular lamp according to the first embodiment, the PWM dimming control circuit 1 can absorb the variation of the load lighting circuit 2 and can make the load 3 to be turned off.

  For example, when the load 3 is a side marker lamp provided on each of the left and right sides of the vehicle, the left side marker lamp disappears and the right side marker lamp disappears. In the case where the load 3 is a cornering lamp composed of a plurality of lamp units, the plurality of lamp units disappear. Further, when the load 3 is a room lamp, the lamp disappears before replacement and the lamp disappears after replacement.

  In the vehicular lamp according to the first embodiment, the linear range is a range D3 obtained by adding a predetermined range D2 to the variation range D1 of the load lighting circuit 2 as shown in FIG. . The predetermined range D2 is minimized, and the linear range D3 is minimized. As a result, as shown in FIG. 2 and FIG. 3, the above-mentioned quadratic curve formula can be obtained between the extinction start time C and the linear formula start time D. For this reason, it is possible to maintain the visibility characteristic which is the purpose of the quadratic curve formula. That is, turning off the load 3 is not an uncomfortable way of disappearing.

  In the vehicular lamp according to the first embodiment, the linear range may be at least the variation range D1 of the load lighting circuit 2. That is, the slope of the duty ratio change between at least the first predetermined value Y% and the second predetermined value X% of the duty ratio may be a linear expression. The first predetermined value Y% is the maximum value among the minimum duty ratios that can be responded in the variation range D1 of the load lighting circuit 2. The second predetermined value X% is the minimum value among the minimum duty ratios that can be responded in the variation range D1 of the load lighting circuit 2.

  By setting the linear range to a range D3 obtained by adding a predetermined range D2 to the variation range D1 of the load lighting circuit 2, there is a margin with respect to the variation range D1 of the load lighting circuit 2. Therefore, it is possible to use an inexpensive load lighting circuit having a large variation. That is, it is possible to use an inexpensive load lighting circuit whose minimum duty ratio that can be responded is Z% larger than Y%. The straight line range D3 may be expanded to a range up to complete extinction (0%) as indicated by a two-dot chain arrow in FIG.

(Description of Embodiment 2)
FIG. 6 shows Embodiment 2 of the vehicular lamp according to the present invention. In the figure, the same reference numerals as those in FIGS. 1 to 5 denote the same components. Hereinafter, the vehicular lamp in the second embodiment will be described.

  As shown in FIGS. 2 and 3, the vehicular lamp according to the first embodiment has a quadratic curve formula from the turn-off start time C to the linear start time D. On the other hand, as shown in FIG. 6, the vehicular lamp according to the second embodiment has two linear types between the extinguishing start point C and the linear start point D. The linear slope at the turn-off start time point C side is larger than the linear slope at the straight line start time point D side. Further, the linear inclination on the linear expression start point D side is larger than the linear inclination from the linear expression start point D. Note that there may be three or more linear expressions between the extinction start point C and the linear start point D.

1 PWM dimming control circuit 2 Load lighting circuit 3 Load

Claims (3)

A PWM dimming control circuit;
A light source that is dimmed and extinguished by the PWM dimming control circuit;
A load lighting circuit that is connected between the PWM dimming control circuit and the light source, and switches on / off of power supply to the light source in accordance with PMW dimming control by the PWM dimming control circuit;
With
The PWM dimming control circuit includes:
While changing the duty ratio, which is the ratio of the lighting time of the light source with respect to one cycle of the PWM dimming control, from the lighting state to the extinguishing state, the load lighting circuit changes in a tendency to decrease with time. Control
Wherein the linear equation of the slope of the duty ratio changes in a range of at least from a first predetermined value to a second predetermined value of the duty ratio, the first predetermined value or more of the slope of the duty ratio changed a quadratic curve equation of the curve,
Wherein the first predetermined value, Ri higher duty ratio der than the second predetermined value,
The range from the first predetermined value to the second predetermined value is equal to or substantially equal to the range of variation in the minimum duty ratio that can respond to the PWM dimming control in the load lighting circuit, or from the range of variation. Is great,
A vehicular lamp characterized by the above. The first predetermined value is a maximum value among the minimum duty ratios in the range of variation .
The vehicular lamp according to claim 1 . The second predetermined value is a value lower than a minimum value among the minimum duty ratios in the range of variation .
The vehicular lamp according to claim 1 or 2 .

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