Light source control device

Abstract

Even when the processor enters a sleep or shutdown state, or when power supply from the power circuit is stopped due to the system being turned off, it is possible to control the illumination or blinking of light sources such as indicators without the processor continuing to output control signals, through a simplified configuration. [Solution] The light source control device 1, which controls the operation of the light source of the display unit, comprises a processor 12, a power supply circuit 10, a light source drive circuit 22, and a latch circuit 16. The processor causes the latch circuit to hold a predetermined value ("1") when the processor enters sleep mode or shutdown mode, or when the power supply from the power supply circuit is stopped, thereby enabling the light source to be driven by the light source drive circuit during a first period in which the predetermined value is held in the latch circuit.

Description

Technical Field

[0001] The present invention relates to a light source control device mounted on a vehicle such as an automobile.

Background Art

[0002] Patent Document 1 discloses a configuration in which a CPU directly controls a security indicator in a security system having an indicator for displaying the operating state of the CPU (FIG. 1 etc.).

[0003] Patent Document 2 discloses a configuration in which when the ignition key is removed and the vehicle is not operating, the security indicator is constantly blinking to notify the occupant that the vehicle's security system is operating normally (FIG. 1, FIG. 4 etc.).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a result of the study by the present inventors, the following problems have become clear. (1) When adopting a configuration in which a processor (CPU, MPU, etc.) directly controls a security indicator as in Patent Document 1, during the period when the indicator is blinking, a control signal (H / L signal) must be constantly transmitted from the processor. For this control, for example, a processor in sleep mode consumes extra power, which causes a problem that the battery life is shortened. (2) Furthermore, in some power management systems for vehicles, for example, a power management ECU (Electronic Control Unit) acting as a master device for managing power selects a slave ECU to be controlled from a group of multiple slave ECUs (slave ECU group), and, for example, sends selective wake-up / sleep / shutdown commands to the selected ECU via CAN (Controller Area Network) communication, thereby individually setting the ECU to wake-up (start-up state), sleep (low power consumption state), or shutdown (power supply stopped state). Furthermore, in a vehicle, for example, if the ignition key is removed and the ignition is turned off, the vehicle's onboard systems shut off, and most of the multiple ECUs are left without power. Here, we assume a scenario where one of the slave ECUs functions as a light source control device for a security indicator attached to an instrument display, and while the security indicator is flashing, a shutdown command for the ECU is input via CAN communication, or the power supply to the ECU (light source control device) is cut off (effectively a shutdown) when the ignition key is removed and the system is turned off. In this case, simply shutting down the ECU (Light Source Control Unit) would result in the processor's power being cut off, preventing the security indicator from lighting up or blinking. One possible solution is to adopt a configuration with a main CPU and a sub-CPU. During shutdown, only the main CPU would be shut down, while the sub-CPU would remain operational, maintaining control over the blinking of the security indicator. However, this method requires two processors, complicating the configuration and increasing power consumption. This contradicts the need for simplification of vehicle systems and drastic reduction of power consumption, making the adoption of the above method difficult. (3) Thus, in conventional control circuits for the illumination (flashing) of security indicators, the processor must constantly send control signals (H / L signals) while the indicator is flashing, which leads to the problem that the processor consumes extra power while in sleep mode for this control; the problem that the indicator cannot flash when the processor enters shutdown mode in response to a command sent via CAN communication, etc.; and the problem that the indicator cannot flash when the power supply to the processor is stopped. (4) Patent documents 1 and 2 mentioned above do not describe the problems described in (3) above, nor do they mention any countermeasures for those problems.

[0006] One of the objectives of the present invention is to enable, with a simplified configuration, to control the illumination or blinking of light sources such as indicators, without the processor continuing to output control signals, even when the processor is in a sleep state or shutdown state, or when the power supply from the power circuit is stopped due to the system being turned off.

[0007] Other objects of the present invention will become apparent to those skilled in the art by referring to the embodiments and best embodiments described below, as well as the accompanying drawings. [Means for solving the problem]

[0008] The following are examples of embodiments of the present invention to facilitate understanding of its outline.

[0009] In a first embodiment, the light source control device is a light source control device that controls the operation of a light source of a display, and includes a processor that outputs a first control signal as a digital signal used for controlling the operation of the light source, a power supply circuit that supplies power to the processor and can change the manner in which the power supply to the processor is supplied to the processor, thereby enabling the processor, which is in a normal operating state, to switch to a sleep mode or shutdown mode, or can stop supplying the power to the processor in accordance with the system to which the light source control device belongs to being turned off, a light source drive circuit that drives the light source, and a latch circuit that temporarily holds a value determined by the first control signal output from the processor, and when the held value is a predetermined value, the latch circuit outputs a second control signal that enables the light source to be driven by the light source drive circuit, wherein when the processor switches to a sleep mode or shutdown mode, or when the power supply from the power supply circuit is stopped, the first control signal causes the latch circuit to hold the predetermined value, and during a first period in which the predetermined value is held in the latch circuit, the light source drive circuit drives the light source to turn on or blink the light source.

[0010] In the first embodiment, when the processor enters a sleep / shutdown / power supply cut-off state, a first control signal as a digital signal is supplied to a latch circuit to cause the latch circuit to hold a predetermined value (e.g., "1"), and during the first period in which the predetermined value is held, a second control signal output from the latch circuit makes the light source drive circuit drivable, causing the light source drive circuit to turn on or blink the light source. According to this embodiment, since the output of the latch circuit is used as a control signal to operate the light source drive circuit, the processor does not need to be responsible for controlling the drive of the light source. Therefore, when the processor enters sleep mode, the power supply voltage can be sufficiently reduced to significantly reduce power consumption. Furthermore, since the processor does not need to be responsible for controlling the operation of the light source, it is possible to shut down the processor without any problems. This also contributes to reducing power consumption. Furthermore, since the output of the latch circuit can be used as a control signal to operate the light source drive circuit, the light source can be turned on or blinked even after the processor has shut down.

[0011] In this embodiment, the above effects can be obtained simply by adding a simplified circuit called a latch circuit, and the complexity of the device configuration and the increase in power consumption can be sufficiently suppressed. Thus, according to this embodiment, even when the processor is in a sleep state or shutdown state, or when the power supply from the power circuit is stopped due to the system being turned off, it is possible to control the lighting or blinking of light sources such as indicators without the processor continuing to output control signals, using a simplified configuration.

[0012] In a second embodiment dependent on the first embodiment, when the processor transitions to the shutdown mode or when the power supply from the power supply circuit is stopped, during the first period the processor sets the latch circuit and after the elapsed time the processor enters a sleep state, a shutdown state, or a power-off state.

[0013] In this embodiment, for example, the processor may be immediately switched to a shutdown state after setting the latch circuit, or the processor may be switched to a shutdown mode after being put into sleep mode.

[0014] In a third embodiment dependent on the first or second embodiment, the second control signal output from the latch circuit during the first period is a DC voltage signal of a predetermined level, and the DC voltage signal may be supplied to the light source drive circuit as a control signal for the light source drive circuit, either at the predetermined level or after being stepped down and converted to the stepped-down level.

[0015] In this embodiment, a configuration is adopted in which a second control signal output from the latch circuit, when a predetermined value (e.g., "1") is held in the latch circuit, is supplied as a control signal to the light source drive circuit. Generally, a method is thought to be employed in which, for example, a binary (H or L) control signal is transmitted (supplied) from a latch circuit to the light source driver circuit, which is the target of control, and a determination circuit in the light source driver circuit determines whether the received control signal is H or L, and then decides whether to drive or not the light source according to the determination result. However, this method requires the light source driver circuit to be equipped with a determination circuit, which increases the number of elements and can lead to the problem of increased power consumption. Therefore, in this embodiment, the output of the latch circuit (second control signal) is supplied to the light source drive circuit as a control signal for the light source drive circuit. With this configuration, when a control signal is supplied from the latch circuit, the light source can be turned on or off, and when no control signal is supplied, the light source cannot be turned on or off. This makes it possible to control the on / off state of the light source drive using only the binary output of the latch circuit, without the need for a determination circuit. Therefore, it becomes possible to control the driving / non-driving of the light source with a simplified configuration without increasing the number of elements or increasing power consumption.

[0016] In a fourth embodiment dependent on any one of the first to third embodiments, a timing control signal for determining the blinking period of the light source is provided in front of the light source drive circuit, and the light source drive circuit may blink the light source at a period based on the timing control signal when the light source drive circuit is in an operational state.

[0017] According to this embodiment, the blinking period of the light source can be determined by the control output of a timing control circuit (for example, which can be composed of an RC oscillator circuit and is always operational when the battery is on) provided in front of the light source drive circuit, thereby making the light source blink at a desired period.

[0018] In a fifth aspect dependent on any one of the first to fourth aspects, the power supply circuit monitors, from the system to which the light source control device belongs, a wake-up / sleep / shutdown command sent by CAN communication and a command to stop supplying the power to the processor due to the shutdown of the system to which the light source control device belongs, and may change the power supply mode to the processor based on the result of the monitoring.

[0019] In this aspect, for example, in an in-vehicle system, the power supply circuit monitors both a command by CAN communication used for power supply control and the stop of power supply accompanying the shutdown of a higher-level system (a system including a power management IC as a master device, etc.) represented by ignition off, and flexibly changes the mode of the voltage supplied to the processor (voltage level, voltage supply timing, or cycle in the case of intermittent supply, etc.) according to the results of these monitorings. Therefore, it is possible to appropriately respond to any of the sleep / shutdown / stop of power supply of the processor, and a light source driving device with high versatility and a simplified configuration can be realized.

[0020] In a sixth aspect dependent on any one of the first to fifth aspects, the display having the light source is a security indicator mounted on a vehicle and capable of displaying the state of the light source control device including normal / abnormal, and the light source control device may function as a security indicator control device that controls the lighting or flashing of the security indicator.

[0021] In this aspect, it is possible to control the lighting or flashing of the security indicator by a light source control device having a simplified configuration and low power consumption that functions as a security indicator control device.

[0022] Those skilled in the art will easily understand that the exemplified aspects according to the present invention can be further modified without departing from the spirit of the present invention.

Brief Description of the Drawings

[0023] [Figure 1] Figure 1 shows an example of the system configuration of the light source control device of the present invention. [Figure 2] Figure 2(A) is a circuit diagram showing the specific configuration of the main parts of the light source control device shown in Figure 1, and Figure 2(B) is a diagram showing an example of the correspondence between the input and output of a latch circuit. [Figure 3] Figure 3 is a sequence diagram of the system including the light source control device shown in Figures 1 and 2(A). [Modes for carrying out the invention]

[0024] The best embodiments described below are used to facilitate understanding of the present invention. Therefore, those skilled in the art should note that the present invention is not unduly limited by the embodiments described below.

[0025] (First Embodiment) Figure 1 shows an example of the system configuration of the light source control device of the present invention. In Figure 1, the light source control device 1 operates when power supply voltage (e.g., VCC: 5V) is supplied from the battery BAT, and controls the operation of the LED 32, which is a light source included in the security indicator 30, which is a display device. Here, the light source control device 1 is described as being mounted on a vehicle and acting as a slave device (e.g., a slave ECU) in the in-vehicle system.

[0026] In Figure 1, the security indicator 30 is a security indicator that informs the occupants that the vehicle's security system is functioning correctly, and the light source control device 1 functions as a security indicator control device that controls the illumination or flashing of the security indicator 30.

[0027] This light source control device 1 includes a power supply circuit (power supply IC) 10, a processor 12 (equipped with a GPIO circuit (General Purpose Input / Output circuit) 14), a latch circuit 16, a timer circuit 18 as a timing control circuit, and an interface (I / F) 20 having a light source drive circuit (LED drive circuit) 22 for driving LEDs as light sources.

[0028] When the battery BAT is ON, the battery BAT is connected to the light source control device 1 via the fuse Fu, thereby supplying the power supply voltage VCC (e.g., 13V) to the power supply terminal VIN of the power supply circuit 10 and the power supply terminal NK of the security indicator 30.

[0029] The power supply circuit (power supply IC) 10 constantly monitors the wake-up / sleep / shutdown commands CS and the ignition signal IS indicating the on / off state of the ignition key (ignition switch), which are sent via CAN communication from a higher-level system (a system that includes a master device such as a power management ECU responsible for power management, although not shown in the diagram). The power supply circuit (power supply IC) 10 is equipped with input terminals CN and IG for the above-mentioned commands CS and ignition signal IS.

[0030] Furthermore, the power supply circuit (power supply IC) 10 outputs, for example, a power supply VCC (for example, 5V) from the first power supply output terminal VO1 during normal operation, and a sleep voltage SLEEP (for example, 1.35V) during sleep mode, to supply power to the power supply input terminal EN1 of the processor 12. Furthermore, VBB (for example, 3.3V) is output from the second power output terminal VO2 and supplied to the power input terminal EN3 of the timer circuit (timing control circuit) 18 and the power terminal EN2 of the latch circuit 16.

[0031] The power supply circuit (power supply IC) 10 having such a configuration can supply power to the processor 12 and, by changing the manner in which power is supplied to the processor 12, can transition the processor 12 from a normal operating state to a sleep mode or a shutdown mode, or can stop supplying power to the processor 12 in response to the system (higher-level system) to which the light source control device 1 belongs being turned off (in this case, the ignition signal IS being turned off).

[0032] When the processor 12 transitions to a sleep state or shutdown state, it supplies the latch circuit 16 with a first control signal as a digital signal (here, a set signal QS and a reset signal QR that control the set / reset of the latch circuit 16).

[0033] The set signal QS, which serves as the first control signal, is output from the first output terminal GA of the GPIO circuit 14 provided in the processor 12 and supplied to the input terminal S of the latch circuit 16, while the reset signal QR is output from the second output terminal GB of the GPIO circuit 14 and supplied to the input terminal R of the latch circuit 16.

[0034] The latch circuit 16 temporarily holds a value (either of two values) determined by a first control signal (set signal QS, reset signal QR) output from the processor 12. When the held first control signal is a predetermined value (here, QS is "1", QR is "0", and the held predetermined value is "1"), a second control signal TC is output, which enables the light source (LED) 32 to be driven by the light source drive circuit 22 provided in the interface (I / F) 20.

[0035] Specifically, as explained using Figure 2, the second control signal TC output from the latch circuit 16 when the latch circuit 16 holds a value of "1" is the control signal of the light source drive circuit 22.

[0036] This second control signal TC is output from the output terminal CT of the latch circuit 16 and supplied to the control signal input terminal JL of the light source drive circuit 22.

[0037] The timer circuit 18 functions as a timing control circuit and, as will be described later with reference to Figure 2, can specifically be composed of an RC oscillator circuit. The timer circuit 18 outputs a timing control signal TM from its output terminal PM and supplies it to the timing control signal input terminal JT of the light source drive circuit 22.

[0038] The light source drive circuit 22 provided in the interface (I / F) becomes operational in response to the second control signal TC during the first period in which a predetermined value (here, "1") is held in the latch circuit 16, and drives the light source (LED) 32 provided in the security indicator 30 to blink at a period determined by the timing control signal TC supplied from the timer circuit (timing control circuit) 18. Note that blinking is just one example, and the light source (LED) 32 may also be kept in a lit state.

[0039] Specifically, the light source drive circuit 22 can make the light source (LED) 32 emit light by setting its cathode to an L level (for example, ground). The control signal for the light source (LED) 32 is output from the control signal output terminal DR of the light source drive circuit 22 and supplied to the cathode of the light source (LED).

[0040] In the light source control device 1 shown in Figure 1, when the processor 12 enters sleep / shutdown / power supply stop states, a first control signal (set signal QS, reset signal QR) as a digital signal is supplied to the latch circuit 16 to cause the latch circuit 16 to hold a predetermined value (for example, "1"). During the first period in which this predetermined value is held, a second control signal TC output from the latch circuit 16 enables the light source drive circuit 22 to be driven, causing the light source drive circuit 22 to light up or blink the light source 32.

[0041] As a result, the output of the latch circuit 16 is used as a control signal (second control signal TC) to operate the light source drive circuit 16, eliminating the need for the processor 12 to control the drive of the light source 32. Therefore, when the processor 12 enters sleep mode, the power supply voltage can be sufficiently reduced to significantly lower power consumption.

[0042] Furthermore, since the processor 12 does not need to be responsible for controlling the operation of the light source 32, it is possible to shut down the processor 12 without any problems. This also contributes to reducing power consumption.

[0043] Furthermore, since the output of the latch circuit 16 can be used as a control signal (second control signal TC) to operate the light source drive circuit 22, the light source 32 can be turned on or blinked even after the processor 12 has shut down.

[0044] The illumination or flashing of the light source 32 can inform the vehicle occupants that the security system is functioning correctly.

[0045] Furthermore, the above effects can be achieved simply by adding a simplified circuit, the latch circuit 16, and the complexity of the device configuration and the increase in power consumption can be sufficiently suppressed.

[0046] Thus, according to the light source control device 1 in Figure 1, even when the processor 12 is in a sleep state or shutdown state, or when the power supply from the power circuit is stopped due to the system being turned off, the processor 12 does not continue to output control signals, and it is possible to control the lighting or blinking of the light source 32 of the indicator (which is interpreted as a broad concept including the security indicator 30) with a simplified configuration.

[0047] Furthermore, in the light source control device 1 of Figure 1, when the processor 12 transitions to shutdown mode, or when the power supply from the power supply circuit 10 is stopped (effectively resulting in a shutdown), the processor 12 may be in a shutdown state or power-off state during the first period in which "1" is held in the latch circuit 16.

[0048] In this case, when the processor 12 shuts down (specifically, when it shuts down by a command via CAN communication, or when it shuts down because the power supply is cut off), the processor 12 may immediately transition from its operating state to a "shutdown state," or it may transition from its operating state to a sleep state and then to a shutdown state.

[0049] In the circuit shown in Figure 1, it is primarily assumed that the processor 12 enters a shutdown state immediately after setting the latch circuit 16 and holding a predetermined value (for example, "1").

[0050] Furthermore, during the first period in which the latch circuit 16 is in the set state, the output of the latch circuit 16 (second control signal TC) can enable the operation of the light source drive circuit 22, making it possible to, for example, drive the security indicator 30 to blink during this period.

[0051] Furthermore, it is possible to subsequently turn off the security indicator 30 using various methods.

[0052] Furthermore, the light source control device 1 in Figure 1, for example in an in-vehicle system, monitors both commands via CAN communication used for power control and the cessation of power supply due to the off-time of a higher-level system (a system including a power management IC as a master device), such as when the ignition is turned off. Based on these monitoring results, the power supply circuit can flexibly change the characteristics of the voltage supplied to the processor 12 (voltage level, voltage supply timing, or period in the case of intermittent supply).

[0053] Therefore, it is possible to appropriately respond to sleep, shutdown, or power supply interruption of the processor 12, thereby realizing a light source driver device with high versatility and a simplified configuration.

[0054] (Second embodiment) Next, refer to Figure 2. Figure 2(A) is a circuit diagram showing the specific configuration of the main parts of the light source control device shown in Figure 1, and Figure 2(B) is a diagram showing an example of the correspondence between the input and output of a latch circuit. In Figure 2(A), the same reference numerals are used for the same parts as in Figure 1. Furthermore, explanations of matters explained in Figure 1 are omitted.

[0055] In the circuit of Figure 2, the second control signal TC output from the latch circuit 16 during the first period in which the latch circuit 16 holds a value of "1" is a high-level signal. In the circuit of Figure 2(A), this second control signal TC is input to the light source drive circuit 22 as a control signal TC' via the diode DP.

[0056] In the circuit shown in Figure 2, the latch circuit 16 is an RS (reset-set) latch circuit using an RS flip-flop, which is constructed by cross-coupling two Noah circuits.

[0057] As explained earlier in Figure 1, the reset signal QR is input to the R terminal of the latch circuit 16, and the set signal QS is input to the S terminal. When the latch circuit 16 is set and holds a "1", a high-level DC voltage signal is output from the Q terminal. When the latch circuit 16 is reset and holds a "0", a low-level DC voltage signal (e.g., ground) is output from the Q terminal. The Qn terminal is not used.

[0058] As previously described, the H-level DC voltage signal output from the Q terminal is supplied to the control signal input terminal JL of the light source drive circuit 22 as a control signal for the light source drive circuit 22.

[0059] In the circuit shown in Figure 2, diode DP has the function of preventing the timing control signal TM output from the light source drive circuit 22 from flowing back into the RS latch circuit 16, thereby ensuring that the RS latch circuit 16 operates normally. In other words, diode DP functions as a reverse current prevention circuit 60. Furthermore, this diode DP also incidentally generates a voltage drop equivalent to the forward voltage, thereby minimizing the power supply voltage supplied to the light source drive circuit 22 and further reducing current consumption. Furthermore, as a secondary effect, the timer circuit 18 operates even when the security indicator 30 is not lit or blinking, driving the light source drive circuit 22. Due to the circuit configuration, the voltage during this drive flows back through the light source drive circuit 22 to the latch circuit 16, but the diode DP can prevent this reverse flow. In other words, the reverse flow prevention effect of the diode DP reduces power consumption accordingly.

[0060] In Figure 2, the second control signal TC output from the Q terminal of the latch circuit 16 is stepped down by the reverse current prevention circuit 60 (as described above, this reverse current prevention circuit 60 also has the function of generating a voltage drop equivalent to the forward voltage of the diode DP, and from this viewpoint, the reverse current prevention circuit 60 can be rephrased as a step-down circuit), and the resulting H-level DC voltage signal is denoted as the second control signal TC'.

[0061] Now, referring to Figure 2(B), the correspondence between the input and output in the latch circuit 16 will be explained. As shown in Figure 2(B), when "0" and "0" are input to terminals S and R, the stored data is retained as before. When "1" and "0" are input, the latch circuit 16 is set and "1" is retained, and the Q terminal outputs a high-level DC voltage signal corresponding to "1" (the Qn terminal becomes "0", but this is invalid). When "0" and "1" are input, the latch circuit 16 is reset and "0" is retained, and the Q terminal outputs a low-level DC voltage signal (ground potential) corresponding to "0" (the Qn terminal becomes "1", but this is invalid). In addition, the input of "1" and "1" is a prohibited input and is invalid.

[0062] Let's return to Figure 2(A) and continue the explanation. In Figure 2(A), the timer circuit 18 is a component of the RC oscillator circuit 40, and this RC oscillator circuit 40 is provided with a charge / discharge circuit (in other words, an RC time constant circuit) 50 that determines the period (or frequency) of the timing control signal TM output by the timer circuit 18.

[0063] The charge / discharge circuit (RC time constant circuit) 50 includes resistors R1 and R2 and a capacitor C2. By appropriately selecting the resistor to be used, the period (frequency) of the pulse signal output by the timer circuit (timing control circuit, RC oscillator circuit) 40 can be variably controlled.

[0064] The light source driving circuit 22 in Figure 2(A) has a Darlington-connected switching transistor circuit (Darlington-connected switching output circuit; hereinafter sometimes simply referred to as the output circuit) 90, which includes Darlington-connected PNP transistor B1 and NPN transistor B2, resistors R10 to R23 and capacitor C10.

[0065] Furthermore, in addition to the LED 32 as a light source, the security indicator 30 also includes a bypass capacitor C20 connected in parallel to the LED (light source) 32 to prevent accidental illumination due to surges, and a bias resistor R30 to prevent accidental illumination due to surges.

[0066] Furthermore, a current limiting resistor R20 is provided in the transmission path of the light source drive signal connecting the light source drive circuit 22 and the security indicator 30.

[0067] Next, we will explain the advantages of adopting a configuration in which a second control signal TC (here, a stepped-down voltage signal TC' obtained by stepping down TC by the stepped-down circuit 60) output from the latch circuit 16, when a predetermined value (for example, "1") is held in the latch circuit 16, is supplied as a control signal to the light source drive circuit 22.

[0068] Generally, it is thought that a method would be adopted in which, for example, a binary control signal (H or L) is transmitted (supplied) from the latch circuit 16 to the light source driving circuit 22 which is the target of control, and the light source driving circuit 22 determines whether the received control signal is H or L using a determination circuit, and decides whether to drive or not drive the light source 32 according to the determination result.

[0069] However, this method requires the addition of a judgment circuit to the light source driving circuit 22, which can lead to an increase in the number of elements and thus an increase in power consumption.

[0070] Therefore, in the circuit shown in Figure 2, the output of the latch circuit 16 (here, the second control signal TC') is supplied as the control signal for the light source drive circuit 22. Specifically, the output of the latch circuit 16 (second control signal TC') is supplied to the collector of the PNP transistor B1. The PNP transistor B1 combines the timing control signal (timing signal) TM supplied from the timer circuit 40 with the second control signal TC', and the output of the PNP transistor B1 is used to turn the NPN transistor B2 on or off. With this configuration, the light source drive circuit 22 can be switched according to the H / L state of the output (second control signal TC') of the latch circuit 22, without a power supply (in other words, without power supply), and this switching can cause the light source (LED) 32 of the security indicator 30 to blink.

[0071] In other words, when a control signal is supplied from the latch circuit 16, transistors B1 and B2, which constitute the Darlington-connected switching transistor circuit (output circuit) 90, become operational, and a binary H / L light source drive signal (pulse signal or pulse oscillation signal) can be output from the light source drive circuit 22 at a period determined by the timing control signal TM supplied from the timer circuit 18. This makes the light source (LED) 32 of the security indicator 30 blink.

[0072] Thus, with the light source driving method using the circuit in Figure 2, the ability to turn the light source 32 on or off can be controlled according to the H / L signal of the control signal to the light source driving circuit 22. Therefore, it is possible to control the on / off state of the drive of the light source 32 using only the binary output of the latch circuit 16, without the need for a judgment circuit.

[0073] Therefore, it becomes possible to control the driving / non-driving of the light source 32 with a simplified configuration without increasing the number of elements or increasing power consumption.

[0074] (Third embodiment) Next, refer to Figure 3. Figure 3 is a sequence diagram of the system including the light source control device shown in Figures 1 and 2(A). Figure 3 describes the operation of each part of the light source control circuit 1 when the ignition key is removed and the system is turned off.

[0075] In the sequence diagram in Figure 3, the battery (power supply) is off before time t1, and it remains off after time t6. However, this also describes the operation when the battery is off, taking into account situations such as when the battery is disconnected during pre-shipment inspection or maintenance. Since the vehicle's battery (BAT) is basically always on, if we do not consider the pre-shipment or maintenance state, the operation in the time interval t1 to t6 in the sequence diagram of Figure 3 will be repeatedly performed.

[0076] In Figure 3, the ignition signal IS is off before time t2, turns on at time t2, and turns off at time t4.

[0077] The CAN signal CS is silent before time t2. At time t2, the wake-up command is turned on, and at time t4, the sleep command is turned on, ending the wake-up process and transitioning to the sleep / shutdown state.

[0078] The power supply circuit (power supply IC) 10 has its power output terminal VO1 in the off state before time t2, turns on at time t2, and returns to the off state at time t3.

[0079] The state of the processor (CPU) 12 is shut down before time t2, wake up (start up) during the period from time t2 to t3, normal operation during the period from time t3 to t4, sleep / shutdown during the period from time t4 to t6, during this period (referred to as the first period) the security indicator can be lit or blinked, and shut down at time t6.

[0080] The set signal QS, which sets the latch circuit 16, rises from "0" to "1" at time t6, becoming active, and as a result the latch circuit 16 enters the set state (holding "1").

[0081] The reset signal QR rises from "0" to "1" at time t2, becoming active, which causes the latch circuit 16 to enter a reset state (a state where it holds "0").

[0082] The state of the latch circuit 16 is shut down before time t1, activated during the period from time t1 to t2, and reset to a state of "0" during the period from time t2 to t3. In Figure 3, this state is indicated as reset (0).

[0083] Furthermore, the state of the latch circuit 16 is a latch state that holds "0" during the period from time t3 to t4 (this state is denoted as latch(0) in Figure 3), a set state (set(1)) during the period from time t4 to t5, a latch state that holds "1" (latch(1)) during the period from time t4 to t5, and a shutdown state at time t6.

[0084] The control signal TC (or TC') is "0" from time t1 to t4, "1" from time t4 to t6, and returns to "0" at time t6.

[0085] The security indicator 30 is off during the period from time t1 to t4 because the security system is not activated. However, if the indicator is used for purposes other than security, the LED 32, which acts as a light source, may light up or blink even during the period from time t1 to t4.

[0086] The security indicator 30 flashes, for example, during the period from time t4 to t6, and turns off at time t6 when the power (battery BAT) is turned off.

[0087] Thus, when the ignition signal IS is turned off at time t4, the CAN signal CS enters a sleep state. In response to this sleep state of the CAN signal, the processor (CPU) 12 enters a sleep state during the period from time t4 to t6. During this period from time t4 to t6, the processor (CPU) 12 sets the latch circuit 16 to hold "1" and outputs a second control signal TC or TC' from the Q terminal of the latch circuit 16.

[0088] Therefore, the security indicator 30 can be lit or blinked after the processor (CPU) 12 has been shut down. After the ignition signal is turned off, the security indicator 30 can be illuminated or flashed to inform the vehicle occupants that the security system is functioning correctly.

[0089] As described above, according to the present invention, even when the processor is in a sleep state or shutdown state, or when the power supply from the power circuit is stopped due to the system being turned off, the processor does not have to continue outputting control signals, and it is possible to control the lighting or blinking of light sources such as indicators with a simplified configuration, thereby easily realizing high functionality of the light source control device.

[0090] The present invention is not limited to the embodiments described above, and various modifications and applications are possible. For example, the term "vehicle" shall be interpreted broadly as "a vehicle for transportation."

[0091] Furthermore, while the above embodiment described the control of lighting or flashing a security indicator, the control targets in the present invention include various types of indicators. The present invention can also be applied to the display control of various display devices (indicators).

[0092] The present invention is not limited to the exemplary embodiments described above, and those skilled in the art will also be able to use the exemplary embodiments described above. The implementation can be easily modified to the extent included in the claims. [Explanation of Symbols]

[0093] 1...Light source control device, 10...Power supply circuit (power supply IC), 12...Processor (CPU), 14...GPIO circuit, 16...Latch circuit, 18...Timer circuit (timing control circuit), 20...Interface (I / F), 22...Light source driver circuit (LED driver circuit), 30...Security indicator, 32...Light source (LED), 50...Charge / discharge circuit (RC time constant circuit), 60...Step-down circuit, 90...Output circuit, QR... Reset signal as the first control signal, QS... Set signal as the first control signal, TC (TC')... Second control signal (including a signal that becomes the power supply voltage for the light source driving circuit), DP... Reverse current prevention / step-down diode.

Claims

1. A light source control device that controls the operation of the light source of a display unit, A processor that outputs a first control signal as a digital signal, which is used to control the operation of the light source, A power supply circuit that supplies power to the processor and, by changing the manner in which the power is supplied to the processor, can transition the processor from a normal operating state to a sleep mode or a shutdown mode, or can stop supplying the power to the processor in response to the system to which the light source control device belongs being turned off. A light source driving circuit for driving the aforementioned light source, A latch circuit that temporarily holds a value determined by the first control signal output from the processor, and which outputs a second control signal that enables the light source to be driven by the light source drive circuit when the held value is a predetermined value, It has, The aforementioned processor, When the processor enters sleep mode or shutdown mode, or when the power supply from the power supply circuit is stopped, the first control signal causes the latch circuit to hold the predetermined value, and during the first period in which the predetermined value is held in the latch circuit, the light source drive circuit drives the light source to turn on or blink the light source. Light source control device.

2. When the processor enters the shutdown mode, or when the power supply from the power supply circuit is stopped, During the first period, the processor sets the latch circuit, and after the elapsed time of the first period, enters a sleep state, a shutdown state, or a power-off state. The light source control device according to claim 1.

3. During the first period, the second control signal output from the latch circuit is a DC voltage signal of a predetermined level. The DC voltage signal is supplied to the light source drive circuit as a control signal for the light source drive circuit, either at the predetermined level or after being stepped down and converted to the stepped-down level. The light source control device according to claim 1.

4. A timing control signal that determines the blinking period of the light source is provided in the preceding stage of the light source drive circuit. The light source drive circuit, when the light source drive circuit is in an operational state, drives the light source to blink at a period based on the timing control signal. The light source control device according to claim 1.

5. The aforementioned power supply circuit is The system to which the light source control device belongs monitors wake-up / sleep / shutdown commands sent via CAN communication, and commands to stop the supply of power to the processor due to the system to which the light source control device belongs being turned off. Based on the results of the monitoring, the power supply mode to the processor is changed. The light source control device according to claim 1.

6. The display unit having the light source is mounted on a vehicle and is a security indicator capable of displaying the status of the light source control device, including normal / abnormal. The light source control device functions as a security indicator control device that controls the illumination or flashing of the security indicator. The light source control device according to claim 1.

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