JP4983198B2 - Automotive dimming circuit - Google Patents

Description

  The present invention relates to a dimming circuit for switching light emission luminance such as an LED for vehicle use.

  Conventionally, this type of dimming circuit is often used for various instruments mounted on automobiles, meters for displaying status, and the like. In general, there is a device that informs the user of a current state or an abnormal state using a light emitting element such as an LED. Here, the light-emitting element is brightened during the day to improve visibility, but when the light-emitting element is brightened at night, it feels dazzling, so when the small light switch is turned on in conjunction with the small light of the car In general, the luminance of the light emitting element is decreased (dimmed).

  As shown in FIG. 3, the dimming circuit used in this case includes a display unit 1, dimming switching means 2 for switching dimming of the display unit 1, a light emitting element 3 disposed in the display unit 1, and a display unit. 1, the controller 4 controls at least two or more driving means 5 for driving the light emitting element 3, current limiting means 6 arranged in series with the driving means 5, and the driving means 5. And a control means 7 (see, for example, Patent Document 1).

  Here, the current limiting means 6 is, for example, a resistor, which limits the current of a light emitting element such as an LED, and has different resistance values.

  The dimming switching means 2 is a switch operated at night, such as a small light switch, and switches whether the light emitting element 3 is dimmed.

This operation will be described. When the small light switch is off (when there is no dimming), the driving means 5 having the smaller resistance value of the current limiting means 6 is driven so that a large amount of current flows through the light emitting element 3. By doing so, the brightness | luminance of the light emitting element 3 is raised and visibility is improved. On the other hand, when the small light switch is on (when dimming is present), the driving means 5 on the side with the larger resistance value of the current limiting means 6 is driven to reduce the current to the light emitting element 3, thereby It reduces brightness, prevents glare at night, and realizes a dimmer circuit that is easier to use.
JP 2004-96032 A

  However, in the conventional configuration, since the current limiting means is arranged in the controller, it is necessary to change the current limiting means in the controller when performing fine adjustments such as variations among light emitting elements among lots.

  In addition, there are many cases where the manufacturer that produces the display unit and the manufacturer that produces the controller are different, and there is a problem that fine adjustment cannot be easily performed because the change is not limited to the display unit alone.

  Furthermore, since the current limiting means of the controller is different, it is necessary to prepare a controller corresponding to the variation in characteristics of the light emitting elements of the display unit, and there is a problem that it is difficult to share the vehicle and it is not easy to develop the vehicle type.

In order to solve the conventional problems, dimming circuit of the present invention, in the display unit, a light emitting element, a first current limiting means for limiting the current of the light emitting elements are arranged, the brightness adjustment of the light emitting element This is done only in the display section.

  As a result, the adjustment of the variation of the light emitting elements can be completed within the display unit, and the fine adjustment is facilitated. Also, the adjustment on the controller side is unnecessary, and thus the sharing of the controller (for example, deployment on different models) is easy. Become.

  The dimming circuit of the present invention makes it easy to adjust the variation of the light emitting elements, and provides a dimming circuit that is easier to use.

  1st invention is equipped with the display part, the dimming switching means which switches a display part to a dimming state, and the controller which controls a display part, and a display part restrict | limits the light emitting element and the electric current of a light emitting element A first current limiting means, and the controller includes at least two or more driving means for driving the light emitting element, a second current limiting means arranged in series with the driving means, and a control means for controlling the driving means. The brightness adjustment of the light emitting element can be performed only within the display unit, and the variation adjustment of the light emitting element can be completed within the display unit, facilitating fine adjustment and adjustment on the controller side. Is unnecessary, it becomes easy to share the controller (for example, vehicle type development, etc.).

  In the second invention, in particular, the control means of the first invention can switch the current flowing to the light emitting element according to the dimming switching means by driving any one driving means by the dimming switching means. Thus, a dimming circuit can be easily realized.

  The third aspect of the invention is to reduce the control means of the first aspect of the invention by driving the drive circuit having the higher resistance value of the second current limiting means when the dimming switching means is dimmed. Since the current is reduced during light, the luminance of the light-emitting element can be reduced, and a dimming function can be easily realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by the form of a present Example.

(Embodiment 1)
FIG. 1 is a block diagram of a dimming circuit according to the first embodiment of the present invention.

  In FIG. 1, the display unit 1 includes a light emitting element 3 and first current limiting means 8 that limits a current to the light emitting element 3, and a dimming switching unit 2 switches the dimming of the display unit 1. The controller 4 controls the display unit 1. The controller 4 includes at least two or more drive means 5 for driving the light emitting element 3 and a second current arranged in series with the drive means 5. A limiting means 9 and a control means 7 for controlling the driving means 5 are provided.

  The operation and action of the dimming circuit configured as described above will be described below.

  The display part 1 represents the operation state arrange | positioned, for example in the instrument panel in a motor vehicle. Depending on the case, there are some which are integrated with the operation switch. The light emitting element 3 is, for example, an LED disposed in the display unit 1 and indicates a state to the user by emitting light.

The first current limiting means 8 determines the luminance of the light emitting element 3 and is, for example, a resistor that limits the current flowing to the light emitting element 3. When the resistance value is increased, the current flowing to the light-emitting element 3 is reduced, so that the luminance is reduced (darkened). On the other hand, when the resistance value is decreased, the current flowing to the light emitting element 3 is increased, so that the luminance is increased (becomes brighter).

  Further, the luminance of the LED is likely to change due to manufacturing variations among lots (the luminance may be different among a plurality of LEDs). For this reason, it is necessary to adjust the luminance according to the variation, and the luminance of the LED can be adjusted by optimizing the resistance value of the first current limiting means 8 by taking advantage of the phenomenon described above.

  The controller 4 controls the display unit 1, and includes two or more driving means 5 for flowing current to the light emitting element 3, and the second current limiting means 9 is connected in series with the driving means 5 and the light emitting element 3. For example, a resistor is provided, and the current flowing to the light emitting element 3 is varied depending on the resistance value.

  In general, the light-emitting element 3 such as an LED notifies the user of a current state or an abnormal state, and the brightness of the light-emitting element 3 is increased during the daytime to improve visibility.

  On the other hand, when the brightness of the light emitting element 3 is brightened at night, it feels dazzling. Therefore, when the small light switch is turned on, the brightness of the light emitting element 3 is dimmed (dimmed). Is common.

  Here, the controller 4 performs an operation of dimming the luminance of the light-emitting element 3 by determining that the dimming switching unit 2, which is a small light switch, for example, is at night when it is on. Specifically, as described in the second and third inventions, when dimming, only the drive circuit 5 (for example, a transistor) on the side having a larger resistance value of the second current limiting means 9 which is a resistor is turned on. By reducing the current flowing to the light emitting element 3, the luminance of the light emitting element 3 is lowered and the dimming function is realized.

  On the other hand, when the dimming switching unit 2 is in the OFF state, the dimming operation is not performed. Therefore, the driving unit 5 having the smaller resistance value of the second current limiting unit 9 is driven, and the current to the light emitting element 3 is driven. By increasing the brightness, the luminance of the light emitting element 3 is increased and the visibility is improved.

  Here, the operation will be specifically described with reference to a circuit diagram. FIG. 2 shows a typical dimming circuit of the present invention.

  The display unit 1 includes a resistor R1 of the first current limiting unit 8 disposed in series with the LED that is the light emitting element 3. The controller 4 is considerably different from the resistors R2 and R3 as the second current limiting means 9, the transistors Q1 and Q2 as the driving means 5, and the control means 7 for controlling the transistors, and SW1 is the dimming switching means 2. Here, it is assumed that the resistance value of R2 <the resistance value of R3.

  The circuit operation will be described below.

  When SW1 is off, the control means 7 determines that there is no dimming, performs Hi output to S1 (S2 is Lo output), and turns on the transistor Q1 on the R2 side having a small resistance value, so that the power supply The current flows through the route of LED → R1 → R2 → Q1 → GND, and the resistance value of R2 is small, so that a large amount of current flows and the brightness of the LED is improved.

On the other hand, when SW1 is on, the control means 7 determines that there is dimming, outputs Hi to S2 (S1 is Lo output), and turns on the transistor Q2 on the R3 side having a large resistance value, thereby supplying power. From LED → R1 → R3 → Q2 → GND, and since the resistance value of R3 is large, only a small amount of current flows and the brightness of the LED decreases, thereby realizing a dimming function.

  The same effect can be obtained even when the R2 resistance value is 0Ω.

  On the other hand, the controller 4 controls various loads and LEDs, and is described here as a controller that controls, for example, a seat heater that warms the seat of an automobile.

  At this time, the controller 4 that controls the seat heater needs to flow a large current by driving the seat heater. However, if the harness wire that flows a large current is routed for a long distance, it easily becomes a noise generation source. There are concerns about the effects of noise on radios and radios. Therefore, it is effective to arrange the controller 4 that drives the seat heater disposed in the seat in the vicinity of the seat.

  However, although the controller 4 is in the vicinity of the seat, the display unit 1 is preferably located in the instrument panel or in the vicinity of the driver's seat in consideration of user convenience. Often placed in.

  In addition, it is more efficient for the seat to be built by the seat maker including the seat heater and the controller, and it is more efficient when incorporated into the car. Often different.

  For this reason, by arranging the first current limiting means 8 capable of adjusting the luminance variation of the light emitting element 3 in the display unit 1 as in the present invention, the variation adjustment of the light emitting element 3 can be adjusted in the display unit 1. It can be completed with. Therefore, the adjustment can be easily performed only by the manufacturer of the display unit 1, and the adjustment on the controller 4 side is not required. Therefore, the controller 4 can be easily shared (for example, development of a vehicle type), and the dimming is easy to use. A circuit can be provided.

  Although the controller for controlling the seat heater has been described as a representative, the present invention is not limited to this application.

  As described above, the dimming circuit according to the present invention can adjust the luminance of the light emitting element only in the display unit, and thus can be applied to a dimming device in which the display unit and the controller are independent.

Block diagram of a dimming circuit according to the first embodiment of the present invention Typical dimming circuit schematic Block diagram of a conventional dimming circuit

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display part 2 Dimming switching means 3 Light emitting element 4 Controller 5 Driving means 6 Current limiting means 7 Control means 8 First current limiting means 9 Second current limiting means

Claims (3)

A display unit, and the dimming switching means for switching the display to the dimming state, and a controller for controlling the display unit, in the display unit, the limits and the light emitting element, the current of the light emitting element place the one current limiting unit, wherein the controller comprises at least two or more drive means for driving the light emitting element, a second current limiting means disposed in series with the drive means, the drive means An in-vehicle dimming circuit comprising a control means for controlling. The in-vehicle dimming circuit according to claim 1, wherein the control means drives any one of the driving means by the dimming switching means. The in-vehicle dimming circuit according to claim 2, wherein the control means drives the driving circuit having a higher resistance value of the second current limiting means when the dimming switching means is dimmed.

Images