JP2011243437A - Illumination dimming device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that the number of constituent components in an illumination-on circuit is increased since light extinction at night is performed by changing a current value.SOLUTION: When a head lamp lighting determination means 40 determines that head lamps are lighted, the pulse train corresponding to the dimming amount instructed by a dimming table 50 and a dimming amount instruction means 60 is generated by a pulse train generation means 30, the generated pulse train is input into a drive circuit 20 and a light source 10 for the illumination is lighted.

Description

  The present invention relates to a vehicular illumination dimming device capable of adjusting (dimming) the illumination brightness of a vehicular meter device or a vehicular display operation device.

  Nowadays, as a vehicle display operation device that performs display operation of in-vehicle devices such as a vehicle meter device, a car navigation device, an audio device, and an air conditioner, it is illuminated with a self-light-emitting meter, a self-light-emitting operation panel, or a backlight. Liquid crystal displays and the like have been put into practical use. In such a self-luminous meter and a self-luminous operation panel, when the key is turned on, the meter and the operation panel are lit regardless of day or night. Moreover, in the liquid crystal display, the backlight is turned on regardless of day or night while the display is being used.

  However, if illumination is performed at the same brightness both day and night with such a self-luminous meter, operation panel, or display, dimming (dimming) is performed to reduce the brightness of the illumination because it is too bright at night. Patent Document 1).

  Furthermore, since the sensitivity of the human eye varies from person to person, and the brightness of the outside world during driving varies greatly depending on the situation, such a self-luminous meter, a self-luminous operation panel, or The display is provided with a dimming function capable of dimming according to the driver's preference regardless of day or night. In general, this dimming function inputs a PWM (Pulse Width Modulation) signal to an illumination drive circuit and changes a duty ratio indicating a ratio of an on time and an off time during one cycle of the PWM signal. Thus, predetermined light control is realized (see Patent Document 1).

JP 2007-149552 A

  However, according to the invention described in Patent Document 1, since the current to be supplied to the illumination is switched in two stages, the switching circuit for turning on / off the illumination and the illumination light source are included in the illumination lighting circuit. In addition to the power supply circuit for supplying power to the transistor, a transistor circuit for switching the current is required. For this reason, there has been a problem that the number of circuit components increases and the circuit scale increases.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a vehicular illumination dimming device capable of dimming at night and dimming at night and day without changing the configuration of a lighting lighting circuit. And

  The vehicle lighting control device according to the present invention is configured such that the cycle of the PWM signal for controlling lighting on / off is set when the vehicle headlamp is lit and the vehicle headlamp is not lit. By setting a longer value than that, nighttime dimming and daytime / nighttime dimming can be performed without changing the configuration of the lighting circuit.

  That is, in the vehicle lighting dimming device according to the present invention, an illumination light source, a drive circuit that drives the illumination light source with a constant current, a dimming step and a dimming amount of the illumination light source are defined. A dimming table; a headlamp lighting determining unit that determines whether or not a vehicle headlamp is lit; a dimming amount instruction unit that instructs a dimming amount of the illumination light source; and the dimming table A pulse train generating means for generating a pulse train for controlling turning on / off of the illumination light source based on the dimming amount stored in the lamp and an instruction of the dimming intensity instruction means and inputting the pulse train to the drive circuit; A period of the pulses generated by the pulse train generating means when the headlamp lighting determining means determines that the headlamp is lit. When it is determined that the headlamp is not lit , And setting to a value that is longer than the period of the pulses generated by said pulse train generating means.

  According to the vehicle lighting dimming device configured as described above, when the headlamp lighting determining unit determines that the vehicle headlamp is lit, the amount of light control defined in the dimming table is set. Among them, the pulse train generating means generates a pulse train having a longer cycle than when it is determined that the headlight of the vehicle is not lit so that the driver performs the light control instructed by the light control instruction means. Then, the generated pulse train is input to the drive circuit, and the illumination light source is turned on by the input pulse train. Therefore, dimming can be performed at a finer resolution than in the daytime at night, and thereby, dimming at night and dimming can be performed at night and day without changing the configuration of the lighting lighting circuit. .

  Further, in the vehicle lighting dimming device according to the present invention, the pulse train generating means generates a reference pulse train based on the light control amount defined in the light control table and the instruction of the light control instruction device. A reference pulse train generating means for generating and a pulse counting means for counting the number of the reference pulses generated by the reference pulse train generating means, and the headlamp is turned on by the headlamp lighting determining means. When the determination is made, each time the pulse counting means counts that the predetermined number of the reference pulses are generated by the reference pulse train generating means, the predetermined number of reference pulses are sent to the drive circuit. It is characterized by outputting.

  According to the vehicle lighting dimming device configured as described above, when the headlamp lighting determining unit determines that the vehicle headlamp is lit, the amount of light control defined in the dimming table is set. Among them, the number of reference pulses generated by the reference pulse train generating means is counted by the pulse counting means based on the dimming amount instructed by the driver by the dimming intensity indicating means, and the reference generated at every predetermined number is counted. A pulse is input to the drive circuit, and the illumination light source is turned on by the input pulse train. Therefore, dimming can be performed at a finer resolution than in the daytime at night, and thereby, dimming at night and dimming can be performed at night and day without changing the configuration of the lighting lighting circuit. .

  According to the vehicle lighting control device according to the present invention, it is possible to perform nighttime dimming and daytime / nighttime control without changing the configuration of the lighting circuit.

1 is a block diagram illustrating a schematic configuration of a vehicle lighting control device according to an embodiment of the present invention. It is a figure which shows the content of the light control table. It is the flowchart which showed the flow of operation | movement of the Example of this invention. It is a figure which shows the content of the signal produced | generated by a pulse train production | generation means. It is a figure which shows the light control range of day and night in the Example of this invention. It is a figure which shows the 2nd example of a setting of the light control range of day and night.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a vehicle lighting dimmer according to the present invention will be described with reference to the drawings.

  In this embodiment, the present invention is applied to a vehicle meter panel, a car navigation device, an audio device, a display operation panel such as an air conditioner, or a vehicle lighting dimming device that performs lighting and dimming of a liquid crystal display. It is. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a block diagram of an embodiment of the present invention. A vehicle lighting dimming device 1 is installed in a vehicle 5 (not shown), and includes a lighting light source 10 including a light emitting diode (LED), a switching element such as a transistor, and a power source, and is a current set based on a power source voltage. The drive circuit 20 that drives the illumination light source 10 with values, the pulse train generation means 30 that generates a pulse train that controls the turning on / off timing of the illumination light source 10 that is input to the drive circuit 20, and the headlamp of the vehicle 5 are turned on The headlamp lighting determining means 40 for determining whether or not the light is adjusted, the dimming table 50 in which the dimming amount of the illumination light source 10 is defined, and the driver of the vehicle 5 adjusting the dimming amount of the illumination light source 10 A dimming amount instruction means 60 for instructing the ignition switch, and an ignition switch state determination means 70 for determining the state of the ignition switch of the vehicle 5.

The pulse train generating means 30 has a function of generating a predetermined pulse train by performing modulation called pulse width modulation (PWM). If one period of the pulse train generated by the pulse train generating means 30 is T and the ON time of the pulse is T ₀ , the luminance of the illumination light source 10 can be adjusted according to the duty ratio D of the pulse train. Here, the duty ratio D is defined as D = (T ₀ / T) × 100 (%), and the luminance of the illumination light source 10 increases as D increases, and the luminance of the illumination light source 10 decreases as D decreases. Get smaller.

  In the dimming table 50 in which the dimming characteristics of the illumination light source 10 are defined, the dimming step and the dimming light amount corresponding to each dimming step are defined by the duty ratio D as shown in FIG. Yes.

  Here, the pulse train generating means 30 is specifically composed of a reference pulse train generating means 34 for generating a reference pulse train having a duty ratio D corresponding to the light control amount instructed by the light control amount instruction means 60, and a reference pulse train generating means 34. It comprises pulse counting means 36 for counting the number of reference pulses included in the generated reference pulse train.

  Next, the effect | action of the vehicle illumination light control apparatus 1 which concerns on a present Example is demonstrated based on the flowchart of FIG.

  The ignition switch state determining means 70 confirms that the ignition switch of the vehicle 5 is ON (S1 in FIG. 3), and the subsequent processing is started. First, the contents of the dimming table 50 are read according to an instruction from the reference pulse train generation means 34 (S2 in FIG. 3).

  The driver of the vehicle 5 instructs the dimming amount during the daytime or at night by the dimming amount instruction means 60 (S3 in FIG. 3). This instruction is performed by selecting a dimming step of the dimming table 50 shown in FIG. Specifically, a brightness adjustment knob may be installed near the meter of the vehicle 5, and the dimming step may be instructed by operating the knob. A dimming step setting screen may be displayed on the screen, and the dimming step may be instructed while viewing the screen.

  The dimming step is instructed by inputting a pulse train generated by a procedure described later to the drive circuit 20 by the pulse train generating means 30 when the headlamp of the vehicle 5 is not lit, and turning on the illumination light source 10. The lighting is performed while the driver visually confirms the light that is actually dimmed. In addition, when the headlamp of the vehicle 5 is lit, the pulse train generating means 30 inputs the pulse train generated for the night into the drive circuit 20 by the procedure described later, and turns on the illumination light source 10, This is performed while the driver visually confirms the light that is actually dimmed.

  In this way, different dimming steps can be indicated day and night. The value of the duty ratio D corresponding to the instructed dimming step is read into the reference pulse train generating means 34, and the dimming amount instruction is completed.

  Thereafter, actual dimming is performed. First, the headlamp lighting determination unit 40 determines whether or not the headlamp of the vehicle 5 is lit (S4 in FIG. 3).

  When it is determined that the headlamp is not lit, the duty ratio corresponding to the daytime dimming step is determined based on the daytime dimming step instructed by the reference pulse train generation unit 34 by the dimming amount instruction unit 60. A reference pulse train M of D is generated (S5 in FIG. 3).

  The reference pulse train M having the duty ratio D is a reference pulse train having one cycle T (s) and a duty ratio D (%) by continuing n pulses having the minimum pulse width τ that can be generated by the reference pulse train generation means 34. Is obtained by generating a pulse train having a pulse width nτ determined by nτ = DT / 100.

  Next, the reference pulse train M generated by the reference pulse train generator 34 is input to the drive circuit 20 (S6 in FIG. 3), and the illumination light source 10 is turned on and off (S7 in FIG. 3). After that, it is confirmed that the ignition switch of the vehicle 5 is ON (S8 in FIG. 3) and that the headlamp is not lit (S9 in FIG. 3). Returning to S6 of 3, the lighting light source 10 is repeatedly turned on and off.

  On the other hand, when the ignition switch state determining means 70 determines that the ignition switch of the vehicle 5 is OFF (S8 in FIG. 3), the process proceeds to S17 in FIG. 3 and the process ends, and in S9 in FIG. If it is determined that the headlamp is lit, the process proceeds to S10 in FIG.

  If it is determined in S4 of FIG. 3 that the headlamp is lit, the reference pulse train generation unit 34 performs nighttime dimming based on the nighttime dimming step instructed by the dimming amount instructing unit 60. A reference pulse train N having a duty ratio D corresponding to the dimming step is generated (S10 in FIG. 3). The method for generating the reference pulse train N is the same as the method for generating the reference pulse train M described above.

  Subsequently, the number of reference pulses included in the reference pulse train N generated by the reference pulse train generating means 34 is counted by the pulse counting means 36 (S11 in FIG. 3). The counting of the reference pulse number may be performed by software, or may be performed by hardware having a counter function.

  The pulse counting means 36 stores in advance a predetermined value A corresponding to nighttime light reduction. In the present embodiment, it is assumed that the light is reduced to ¼ at daytime at night, and a value of A = 4 corresponding to the reduced light amount ¼ is stored.

  Each time the pulse counting means 36 determines that the reference pulse number has reached a predetermined value A (4 in this embodiment) as shown in FIG. 4 (when S12 in FIG. 3 is Yes), Only the reference pulse generated when the predetermined value A is reached is input to the drive circuit 20 (S13 in FIG. 3).

  In the case of the present embodiment, a pulse train thinned by ¼ with respect to the reference pulse train generated by the reference pulse train generating means 34 (hereinafter referred to as a thinned pulse train) is input to the drive circuit 20.

  The drive circuit 20 is driven by the inputted thinning-out pulse train and turns off the illumination light source 10 (S14 in FIG. 3). After that, it is confirmed that the ignition switch of the vehicle 5 is ON (S15 in FIG. 3) and that the headlamp is lit (S16 in FIG. 3). Returning to S11 of 3, the lighting light source 10 is repeatedly turned on and off.

  On the other hand, when the ignition switch state determination means 70 determines that the ignition switch of the vehicle 5 is OFF (S15 in FIG. 3), the process proceeds to S17 in FIG. 3 and the process ends, and in S16 in FIG. If it is determined that the headlamp is not lit, the process proceeds to S5 in FIG.

  On the other hand, if the pulse counting means 36 determines that the number of pulses does not reach the predetermined value A (when S12 in FIG. 3 is No), the counting of the reference pulse number is continued until it reaches the predetermined value A ( S11 in FIG.

  Note that the steps of S2 and S3 in FIG. 3 are actually steps that are appropriately executed in response to a request from the driver, and are therefore implemented so as to be able to respond to an interrupt request.

  FIG. 5 shows day and night dimming characteristics realized by the above processing. The vertical axis in FIG. 5 indicates the luminance of the illumination light source 10, and the horizontal axis in FIG. 5 indicates the dimming step of the illumination light source 10. Further, P1 indicates daytime dimming characteristics, and P2 indicates nighttime dimming characteristics. That is, FIG. 5 shows that dimming is performed at night so that the luminance is 25% of the daytime.

  According to the vehicle lighting dimming device 1 according to the present embodiment configured as described above, when the headlamp lighting determining unit 40 determines that the vehicle headlamp is lit, the dimming table 50 is used. When the pulse train generation means 30 determines that the headlight of the vehicle is not lit so that the driver performs the dimming specified by the dimming intensity instruction means 60 among the dimming quantities defined in Compared to the above, a pulse train having a long period is generated, the generated pulse train is input to the drive circuit 20, and the illumination light source 10 is turned on by the input pulse train, so that the configuration of the lighting lighting circuit is not changed. Dimming at night and day and night dimming can be performed.

  Note that the setting of the dimming characteristics for day and night is not limited to that shown in the above embodiment, but can also be set as shown in FIG.

That is, the luminance when is lit illumination light source with a duty ratio of 100% and I _0, Day dimming characteristic P1 has become a property of dimming in the range of I ₀ intensity from I _0/4 And At this time, if A = 2 is set and the pulse is thinned out to ½, the dimming characteristic P1 ′ is obtained. Further, it is possible to reduce the duty ratio uniformly by 12.5% from the dimming characteristic P1 ′ to obtain the nighttime dimming characteristic P2.

  In this way, by setting the nighttime duty ratio to (D / A−B)% with respect to the daytime duty ratio D%, the range of change of the nighttime dimming characteristic P2 can be widened.

  Here, A is a predetermined value corresponding to the above-described nighttime light reduction, and acts as a parameter for changing the slope of the dimming characteristic. B acts as a parameter representing the duty ratio offset. FIG. 5 shows an example of A = 4 and B = 0, and FIG. 6 shows an example of A = 2 and B = 12.5.

  According to the vehicle lighting control device according to the present invention, as described in the embodiment, a pulse train having a duty ratio that realizes the night lighting control characteristic P2 can be generated. As long as an optical table is prepared and the values A and B are set in advance, various nighttime dimming characteristics P2 can be realized. In this case, it is not necessary to prepare a daytime dimming table and a nighttime dimming table separately.

  It should be noted that when the illumination light source 10 is dimmed at night, if the pulse thinning is too much, the illumination light source 10 may flicker. Therefore, the predetermined values A and B stored in the pulse counting unit 36 need to be set to values that do not cause flickering after performing operation verification in advance.

  Further, in the present embodiment, the operation is described with the amount of light reduction at night set to 1/4, but the amount of light reduction is not limited to 1/4, but 1/8, 1/12, 1/16. These values can be appropriately selected and adopted.

  Furthermore, in the present embodiment, the configuration in which the LED is used as the illumination light source 10 has been described. However, the illumination light source 10 is not limited to the LED, and can be controlled to be turned on / off by a PWM signal like an EL element, for example. Any light source can be used.

  Further, in this embodiment, when it is determined that the headlight of the vehicle 5 is lit, a thinning pulse train is generated by software. However, if the same function can be realized, thinning that meets the conditions is performed. You may implement | achieve using the logic circuit which can output a pulse train.

DESCRIPTION OF SYMBOLS 10 Illumination light source 20 Drive circuit 30 Pulse train generation means 34 Reference pulse train generation means 36 Pulse counting means 40 Headlamp lighting determination means
50 Dimming table 60 Dimming intensity instruction means 70 Ignition switch state determination means

Claims (2)

A light source for illumination;
A driving circuit for driving the illumination light source with a constant current;
A dimming table in which dimming steps and dimming amounts of the illumination light source are defined;
Headlamp lighting determining means for determining whether or not the vehicle headlamp is lit,
A dimming intensity instruction means for instructing the dimming intensity of the illumination light source;
Based on the dimming amount stored in the dimming table and the instruction of the dimming amount instruction means, a pulse train for controlling turning on and off of the illumination light source is generated and input to the drive circuit. Pulse train generating means,
When the headlamp lighting determining unit determines that the headlamp is lit, the period of the pulse generated by the pulse train generating unit is determined by the headlamp lighting determining unit. When it is determined that is not lit, the vehicle illumination dimming device is set to a value longer than the cycle of the pulse generated by the pulse train generation means.   The pulse train generation means includes a reference pulse train generation means for generating a reference pulse train based on a light control amount defined in the light control table and an instruction from the light control light instruction means, and the reference pulse train generation means Pulse counting means for counting the number of the generated reference pulses, and when the headlamp lighting determining means determines that the headlamp is lit, the pulse counting means 2. The vehicle according to claim 1, wherein the predetermined number of reference pulses are output to the drive circuit each time the pulse train generation unit counts that the predetermined number of the reference pulses are generated. Lighting dimmer.

Images