JP6302854B2 - Luminance control apparatus and luminance control method in railway - Google Patents

Description

  The present invention relates to a luminance control device and a luminance control method in a railway.

  2. Description of the Related Art Conventionally, various lighting fixtures including a light emitting module that emits light when supplied with a direct current (for example, an organic EL element or an LED using a light source) have been provided. In this type of lighting fixture, the dimming control of the light emitting module is possible by, for example, supplying a direct current to the light emitting module intermittently at a predetermined cycle and a ratio of a period for supplying the direct current to one cycle. A configuration is known in which the light output of a light emitting module is adjusted by performing PWM (Pulse Width Modulation) control for adjusting a certain duty ratio (for example, Patent Document 1).

  Moreover, the lighting fixture which employ | adopted the light control system called the amplitude control which adjusts the light output of a light emitting module by adjusting the magnitude | size of the direct current supplied to a light emitting module instead of PWM control as mentioned above Is also known.

JP 2006-40872 A

  By the way, LEDs have come to be used in railway light emitters such as special signal light emitters, railway traffic lights, cues, and signs used in railways. Since the railway light emitting device is a device that transmits a current indication (representing a signal or instruction) to the train driver by turning on or off the color lamp, it is desired to emit light with high luminance.

  Patent Document 1 discloses a method for limiting the current flowing to the LED for the purpose of suppressing heat generation by PWM control or preventing damage to the light emitting module, but the lighting time is not long. No technique is disclosed that emits light with high brightness under the conditions of use.

  Accordingly, an object of the present invention is to provide a luminance control device and a luminance control method capable of obtaining high luminance from a railway light emitting device using a light emitting element in order to solve the above-described problems.

In order to solve the above-described problem, the brightness control device of the present invention has a relationship between a light-emitting element that emits light when current is supplied, a duty ratio of the light-emitting element, and a current value permitted by the duty ratio. A brightness control device including a storage unit that stores information to be displayed, a brightness control unit that controls the brightness of the light emitting element, and a setting information receiving unit that receives setting information regarding a duty ratio and a current value input from a user. The storage unit stores information indicating a threshold value of a duty ratio and a threshold value of a current value in the light emitting element, and the luminance control unit receives the duty ratio and the current value received by the setting information reception unit. When the threshold value of either the duty ratio or current value in the light emitting element stored in the storage unit is exceeded, the light emitting element is permitted. Maximum current value that does not exceed the current value of that, and controls the brightness of the light emitting element at a duty ratio that is acceptable in the current value.

  According to another aspect of the brightness control apparatus of the present invention, in addition to the above-described configuration, the storage unit stores information indicating a pulse width corresponding to the relationship between the current value allowed in the light emitting element and the duty ratio. The luminance control unit can specify a pulse width corresponding to the relationship between the current value determined with reference to the storage unit and the duty ratio, and control the luminance of the light emitting element with the specified pulse width. preferable.

In addition, the brightness control method of the present invention has a relationship between a setting information receiving unit that receives setting information related to a duty ratio and a current value input from a user, and a current value permitted by the duty ratio of the light emitting element and the duty ratio. Brightness control used in a brightness control device having a storage unit that stores information indicating a threshold value of a duty ratio and a threshold value of a current value in the light emitting element, and a brightness control unit that controls the brightness of the light emitting element The luminance control unit has a duty ratio and current value received by the setting information reception unit that exceed a threshold value of any one of the duty ratio and current value of the light emitting element stored in the storage unit. A current value that does not exceed a maximum current value allowed in the light emitting element, and a duty cycle that is allowable at the current value. Characterized by the step of controlling the brightness of the light emitting element in a ratio.

  ADVANTAGE OF THE INVENTION According to this invention, the brightness | luminance control apparatus and the brightness | luminance control method which can obtain high brightness | luminance from the railway light-emitting device using a light emitting element can be provided.

It is a block diagram which shows an example of the brightness | luminance control apparatus 1 which is one embodiment of this invention. It is a figure which shows the structural example of the LED drive circuit 3 shown in FIG. It is a figure which shows an example of the relationship between the duty ratio in LED11, the allowable maximum electric current value, and a pulse width. It is a figure which shows the difference of the average luminance at the time of flowing the maximum electric current value according to a duty ratio. FIG. 5 is a diagram showing the relationship between the duty ratio and the time t in FIG. 4, (A) is a diagram showing the relationship between the current I and the time t when the duty ratio is 100%, and (B) is the duty ratio 50 It is a figure which shows the relationship between the electric current I when it is%, and time t. It is a flowchart which shows an example of the control process of the brightness | luminance of LED11 shown in FIG. 6 is a flowchart showing another example of control processing of the LED drive circuit 3 shown in FIG. 6 is a flowchart showing another example of control processing of the LED drive circuit 3 shown in FIG.

  Hereinafter, a brightness control device and a brightness control method according to an embodiment of the present invention will be described with reference to FIGS. In the following description, the brightness control device 1 is used as an LED (Light Emitting Diode, hereinafter simply referred to as “LED”) module of a special signal light emitter for railways, for example, but other devices (for example, It may be used for a TV remote control, an LED module for lighting a surveillance camera, or the like. In addition, special signal light emitters for railroads are located near the railroad tracks, around railroad crossings, etc., and are turned on when an emergency switch (not shown) is pressed during an emergency situation, the near infrared LED blinks, and railway related It is a device that can notify the person of the occurrence of an emergency.

  FIG. 1 is a block diagram showing an example of a brightness control apparatus 1 according to an embodiment of the present invention. The luminance control device 1 in FIG. 1 includes a CPU 2, an LED drive circuit 3, a memory 4, and a setting information receiving unit 5.

  The CPU 2 outputs necessary instructions to the LED drive circuit 3, receives input information supplied from the outside, and reads information from a table 4A stored in a memory 4 to be described later to perform arithmetic processing and temporary storage. A central processing unit that executes storage processing and the like. Note that the CPU 2 can also output necessary instructions to other components of the luminance control device 1 to perform transmission / reception of data signals, execute necessary arithmetic processing, temporary storage processing, and the like.

  The LED drive circuit 3 is a circuit that drives LED11-1, LED11-2,... LED11-n, which will be described later, to emit light based on a control signal from the CPU2.

  FIG. 2 is a diagram showing a configuration example of the LED drive circuit 3 shown in FIG. The LED driving circuit 3 includes an LED 11-1, an LED 11-2,... LED11-n (hereinafter referred to as “LED11” when there is no need to distinguish between them), a booster circuit 12, a control circuit 13, an FET 14-1, FET 14-2,... FET 14-n (hereinafter referred to as “FET 14” when it is not necessary to distinguish between them). The LED drive circuit 3 can drive the LED 11 with an arbitrary drive current and emit light with an arbitrary luminance by a control signal (clock signal, data signal, etc.) from the CPU 2.

  The LED 11 is an example of a light emitting element, and is a semiconductor element that emits light when a voltage is applied in the forward direction. In addition, although the LED drive circuit 3 is configured to include a plurality of LEDs 11, it may be configured from a single LED 11.

  The booster circuit 12 includes a DC-DC converter, and boosts an input voltage Vin supplied from a power supply (not shown) to an output voltage Vout as a drive voltage that can drive the LED 11. The booster circuit 2 supplies the output voltage Vout to the anode of the LED 11.

  The control circuit 13 controls the luminance of the LED 11 based on the clock signal and data signal supplied from the CPU 2. The control circuit 13 receives a control signal (clock signal and data signal) supplied from the CPU 2 via a bus (data bus or address bus), and performs PWM control based on the received control signal. The controller 13B and a current controller 13C that supplies a pulse voltage signal for PWM control to the gate of the FET 14 are provided.

  The FET 14 is an N channel type FET. The drain of the FET 14 is connected to the cathode of the LED 11. The source of the FET 14 is grounded. The FET 14 performs a switching operation using the pulse voltage signal supplied from the control circuit 13 as a gate voltage. The drive current flowing through the LED 11 is controlled by this switching operation.

  In the memory 4, a table 4A is recorded. Table 4A shows information on the maximum current value allowed in the LED 11, information on the duty ratio allowed in the LED 11, and the relative magnification of the average luminance when each duty ratio is compared with 100% duty ratio. Information to be shown is recorded. In the table 4A, information indicating a relationship between a current value and a pulse width, which will be described later with reference to FIG. 3, is also recorded.

  The setting information receiving unit 5 receives information (specific duty ratio, current value, pulse width, etc.) input from the user and supplies it to the CPU 2. Note that the setting information receiving unit 5 can also receive an instruction from the user such that the duty ratio, current value, pulse width, and the like are not specific numerical values but arbitrary values.

  Then, the characteristic of LED11 is demonstrated. FIG. 3 is a diagram illustrating an example of the relationship between the duty ratio in the LED 11 and the allowable maximum current value and pulse width. As shown in FIG. 3, for example, the maximum current value allowed according to the pulse width is determined by the duty ratio of the LED 11.

  FIG. 4 is a diagram showing a difference in average luminance when a maximum current value corresponding to the duty ratio is passed. As shown in FIG. 4, when a duty ratio of 100% is used as a reference, at a duty ratio of 50%, 0.25 A can be passed and the average luminance is 1.25 times. Further, when the duty ratio is 50%, the current can flow up to 0.25 A, and the average luminance becomes 1.25 times. Further, when the duty ratio is 25%, it is possible to flow up to 0.6 A, and the average luminance becomes 1.5 times. Note that the information shown in FIGS. 3 and 4 is stored in the table 4A shown in FIG.

  FIG. 5 is a diagram showing the relationship between the duty ratio and the time t in FIG. 4, (A) is a diagram showing the relationship between the current I and the time t when the duty ratio is 100%, and (B) FIG. 5 is a diagram showing the relationship between current I and time t when the duty ratio is 50%. As shown in FIG. 5, when the duty ratio is 50%, the current can flow three times more than when the duty ratio is 100%. As described above, by flowing the maximum current value corresponding to the duty ratio to the LED 11, high luminance can be obtained without damaging the LED 11. The control circuit 13 uses the characteristics of the LED 11 to control the LED 11 to emit light with high luminance.

  Next, a method for controlling the brightness of the LED 11 (control processing) will be described with reference to the flowcharts of FIGS. Note that the luminance control apparatus 1 does not necessarily execute all of the control processes shown below, and may execute any of the control processes shown below. Moreover, you may make it the brightness | luminance control apparatus 1 perform combining the control process shown below and another control process.

(First control method)
FIG. 6 is a flowchart showing an example of the luminance control process of the LED 11 shown in FIG. First, when the user inputs a duty ratio, the setting information receiving unit 5 receives the input information (STEP 1). Then, the CPU 2 determines whether or not the duty ratio setting information received and supplied by the setting information receiving unit 5 in STEP 1 is arbitrarily set (STEP 2). In STEP 2, if the setting information of the duty ratio is arbitrarily set, the CPU 2 refers to the table 4 A stored in the memory 4 so that the maximum current value permitted by the LED 11 is obtained. The ratio is selected (STEP 3), and a control signal is supplied to the LED drive circuit 3. Based on the control signal supplied from the CPU 2, the control circuit 13 of the LED drive circuit 3 determines a current value to be energized and a duty ratio, and executes a luminance control process.

  According to such control, if the LED 11 has a characteristic that allows a large amount of current to flow instantaneously, the duty ratio can be lowered as compared with the case where the current is always energized (that is, the duty ratio is 100%). Therefore, the average luminance can be effectively improved while suppressing heat generation.

(Second control method)
FIG. 7 is a flowchart showing another example of control processing of the LED drive circuit 3 shown in FIG. First, when the user inputs a current value, the setting information receiving unit 5 receives the input information (STEP 11). Then, the CPU 2 determines whether or not the current value setting information received and supplied by the setting information receiving unit 5 in STEP 11 is arbitrarily set (STEP 12). If the current value setting information is arbitrarily set in STEP 12, the CPU 2 refers to the table 4A stored in the memory 4 so as not to exceed the maximum current value permitted by the LED 11. A duty ratio is selected (STEP 13), and a control signal is supplied to the LED drive circuit 3. Thereby, the control circuit 13 of the LED drive circuit 3 determines the current value to be energized based on the control signal supplied from the CPU 2 and executes the brightness control process.

  According to such control, if the LED 11 has a characteristic that allows a large amount of current to flow instantaneously, the duty ratio can be lowered as compared with the case of constant power supply (that is, the duty ratio is 100%). Therefore, the average luminance can be effectively improved while suppressing heat generation. Further, since the CPU 2 performs control so as not to exceed the maximum current value permitted by the LED 11, it is possible to prevent the LED 11 from being destroyed.

(Third control method)
FIG. 8 is a flowchart showing another example of control processing of the LED drive circuit 3 shown in FIG. First, when the current value and the duty ratio are input so that the user can adjust the dimming as desired, the CPU 2 receives the input information (STEP 21). Then, the CPU 2 refers to the table 4A and determines whether any of the current value and the duty ratio received in STEP 21 has exceeded these threshold values (STEP 22). If the CPU 2 determines in STEP 22 that one of the threshold values has not been exceeded (NO in STEP 22), the CPU 2 generates a control signal for the received current value and duty ratio and sends it to the control circuit 13 of the LED drive circuit 3. (STEP 23). On the other hand, if it is determined in STEP 22 that either threshold is exceeded (YES in STEP 22), the CPU 2 does not exceed the maximum current value and duty ratio permitted by the LED 11 with reference to the table 4A. Thus, the current value and the duty ratio are selected, and the control signal is supplied to the LED drive circuit 3 (STEP 23). Thereby, the control circuit 13 of the LED drive circuit 3 determines the current value to be energized based on the control signal supplied from the CPU 2 and executes the brightness control process.

  According to such control, if the LED 11 has a characteristic that allows a large amount of current to flow instantaneously, the duty ratio can be lowered as compared with the case where the current is always energized (that is, the duty ratio is 100%). Therefore, the average luminance can be effectively improved while suppressing heat generation. Further, when the current value or duty ratio set by the user exceeds the threshold value registered in the table 4A, the CPU 2 selects the maximum current value and duty ratio that are allowed not to destroy the LED 11. Thus, the control process can be executed.

  As described above, the luminance control device 1 provides information indicating the relationship between the LED 11 (light emitting element) that emits light when a current is supplied, the duty ratio of the LED 11, and the current value permitted by the duty ratio. Including a memory 4 (an example of a storage unit) that stores a table 4A including, and a CPU 2 (an example of a luminance control unit) that controls the luminance of the LED 11, the CPU 2 having a duty ratio acquired from the table 4A of the memory 4, Since the luminance of the LED 11 is controlled by the current value allowed by the duty ratio, a high luminance can be obtained from the railway light emitting device using the LED 11 when compared with a normal light emitting method of the LED 11.

  Further, the luminance control apparatus 1 has a setting information receiving unit 5 that receives setting information related to the duty ratio input from the user, and the CPU 2 receives the setting information receiving unit 5 as described with reference to FIG. When the duty ratio is set to an arbitrary value, the LED 11 has the maximum current value allowed in the LED 11 with reference to the table 4A of the memory 4 and the duty ratio allowed in the maximum current value. Since the brightness ratio is controlled, the duty ratio can be lowered as compared with the case of always energizing (that is, the duty ratio is 100%), so that the average brightness can be effectively improved while suppressing heat generation. Become.

  Further, as described with reference to FIG. 7, the CPU 2 of the brightness control device 1 refers to the table 4 </ b> A of the memory 4 when the current value received by the setting information receiving unit 5 is set to an arbitrary value. Since the brightness of the LED 11 is controlled by the current value that does not exceed the maximum current value allowed in the LED 11 and the duty ratio that is allowed by the current value that does not exceed the maximum current value, in addition to the effects described above. Thus, the LED 11 can be prevented from being destroyed.

  Further, the table 4A of the memory 4 stores information indicating the duty ratio threshold value and the current value threshold value in the LED 11, and the CPU 2 of the luminance control device 1, as described with reference to FIG. 5, when the duty ratio and current value received in 5 exceed the threshold values of the duty ratio and current value in the LED 11 stored in the table 4 </ b> A of the memory 4, the maximum current value allowed in the LED 11. In addition to the above-described effects, the current value or duty ratio set by the user is added to the table 4A in the table 4A. If the registered threshold is exceeded, the maximum current value allowed to avoid destroying the LED 11 It is possible to execute the control process by selecting the fine duty ratio.

  Further, as shown in FIG. 3, the table 4A of the memory 4 stores information indicating the pulse width corresponding to the relationship between the current value allowed in the LED 11 and the duty ratio. Since the pulse width corresponding to the relationship between the current value determined by any one of the control methods 8 and the duty ratio is specified and the luminance of the LED 11 is controlled by the specified pulse width, the LED 11 is destroyed. Can be prevented.

  The control processing described with reference to FIGS. 6 to 8 can be executed by hardware or can be executed by software. When these processes are executed by software, a program constituting the software may execute various functions by installing a computer incorporated in dedicated hardware or various programs. For example, it is installed from a program recording medium in a general-purpose personal computer or the like.

  The program executed by the computer may be a program that is processed in time series in the order described in this specification, or in parallel or at a necessary timing such as when a call is made. It may be a program for processing.

  The embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, the table 4 </ b> A stored in the memory 4 may be configured to be included in the LED drive circuit 3. Moreover, you may comprise so that the control circuit 13 of the LED drive circuit 3 may have the brightness | luminance control function of CPU2.

DESCRIPTION OF SYMBOLS 1 ... Luminance control apparatus, 2 ... CPU (an example of a luminance control part), 3 ... LED drive circuit, 4 ... Memory, 4A ... Table, 5 ... Setting information reception part, 11 ... LED, 12 ... Booster circuit, 13 ... Control Circuit, 14 ... FET,

Claims (3)

A light emitting element that emits light when supplied with current;
A storage unit for storing information indicating a relationship between a duty ratio of the light emitting element and a current value allowed by the duty ratio;
A luminance control unit for controlling the luminance of the light emitting element;
A brightness control device having a setting information receiving unit that receives setting information related to a duty ratio and a current value input by a user;
The storage unit stores information indicating a duty ratio threshold value and a current value threshold value in the light emitting element ,
The brightness control unit
When the duty ratio and current value received by the setting information receiving unit exceed any threshold value of the duty ratio and current value of the light emitting element stored in the storage unit, the light emitting element is allowed. The luminance of the light emitting element is controlled by a current value not exceeding the maximum current value and a duty ratio allowed in the current value ;
A brightness control apparatus characterized by the above. The brightness control apparatus according to claim 1,
The storage unit stores information indicating a pulse width corresponding to a relationship between a current value and a duty ratio allowed in the light emitting element,
The brightness control unit
The pulse width corresponding to the relationship between the current value and the duty ratio determined by the method according to claim 1 with reference to the storage unit is specified, and the luminance of the light emitting element is controlled by the specified pulse width.
A brightness control apparatus characterized by the above. A setting information receiving unit that receives setting information related to a duty ratio and a current value input by a user; information indicating a relationship between a duty ratio of the light emitting element and a current value permitted by the duty ratio; and a duty in the light emitting element A luminance control method used in a luminance control apparatus having a storage unit that stores information indicating a ratio threshold value and a current value threshold value, and a luminance control unit that controls the luminance of the light emitting element,
When the luminance control unit receives the duty ratio and current value received by the setting information reception unit exceed a threshold value of either the duty ratio or current value of the light emitting element stored in the storage unit, the light emission Controlling the luminance of the light emitting element with a current value not exceeding a maximum current value allowed in the element and a duty ratio allowed in the current value ,
The brightness control method characterized by the above-mentioned.

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