Patent Description:
There is known a vehicle lamp that draws light with an irradiation pattern of a predetermined shape on a road surface around a vehicle. (For example, refer to <CIT>). Here, when the irradiation pattern as described above is drawn on the road surface and the road surface is captured by a camera and displayed on a monitor (display device), so-called white clipping (a phenomenon in which gradation is lost and becomes pure white) may occur in a portion which corresponds to the irradiation pattern in the displayed image, making it difficult to grasp road surface condition such as the presence or absence of an obstacle.

This is because the ratio of the highest brightness to the lowest brightness captured by a typical camera is about <NUM> times whereas the ratio of the irradiation pattern brightness on the road surface to the ambient brightness can be about <NUM> times, for example.

Attention is drawn to document <CIT>. Said document sets out to provide an irradiation technology of marking beam for making the beam hard to be erroneously detected as a road surface sign. It suggests a lighting control device, which is a device for controlling a lighting state of a road surface irradiation lamp unit for irradiating a road surface in the vicinity of a vehicle with marking beam, and it includes a control means that sets a turn-off period correspondingly to an imaging period that comes intermittently in which external light is taken in for forming an image in an imaging unit mounted in a vehicle, and controls the road surface irradiation lamp unit to turn off the road surface irradiation lamp unit in the turn-off period during irradiation of the marking beam.

Further attention is drawn to the document <CIT>. It describes a recognition support system for a vehicle that includes an image recognition sensor including a camera configured to capture an image of a periphery of a host vehicle while alternately repeating an exposure period and a non-exposure period; an irradiation device configured to irradiate light to the periphery of the host vehicle; an object recognition unit configured to recognize an object existing in the periphery of the host vehicle by using the image recognition sensor; and a light irradiation control unit configured to, when the object recognized by the object recognition unit is an alert target object, carry out intermittent irradiation of light to the alert target object by using the irradiation device, the intermittent irradiation being carried out such that an irradiation period of light and a non-irradiation period of light are alternately repeated and the non-irradiation period overlaps with at least part of the exposure period.

Also, attention is drawn to the document <CIT>. The document relates to an environment recognition system of a motor vehicle, said system comprising: at least one projector designed to project linear light structures onto an object in front of the motor vehicle; and at least one camera positioned to detect an area in front of the motor vehicle, wherein, in order to detect reflections of the light projected by the projector onto the object, the camera is sensitive to at least a partial range of the frequency spectrum output by the at least one projector, wherein the projector comprises an illuminant arrangement which can be modulated, wherein a controller is provided which is connected to the at least one camera and to the at least one projector, wherein at least one timer is provided in order to clock the projector and camera, wherein the projector is operated by the timer in a pulsed and controlled fashion. Finally, attention is drawn to document <CIT>. The document relates to a lighting system and method for synchronously operating a lighting module and an image capture device of an automotive vehicle such that lanes marked on road and road markings projected by the lighting module can be differentiated without any confusion. The lighting system comprises an image capture device configured to acquire an image of a road of travel of the vehicle; a lighting module configured to project road markings on the road; and a control unit. The control unit is configured to: deactivate the lighting module and to activate simultaneously the image capture device on a first mode, and activate the lighting module and to deactivate simultaneously the image capture device on a second mode.

In a specific aspect, it is an object of the present invention to make it possible to grasp the road surface condition more reliably when the road surface on which the irradiation pattern is formed is captured by a camera.

In accordance with the present invention a controller for lighting control and a vehicle lamp system, as set forth in the independent claims is provided.

According to the above configurations, it is possible to grasp the road surface condition more reliably when the road surface on which the irradiation pattern is formed is captured by a camera.

<FIG> is a block diagram showing the configuration of a vehicle lamp system according to one embodiment. The vehicle lamp system <NUM> of the present embodiment is configured to include a controller <NUM>, a camera <NUM>, a road surface drawing unit <NUM>, a back lamp <NUM>, a switch <NUM> , an object sensor <NUM>, and a monitor (display device) <NUM>. In this embodiment, the controller <NUM> corresponds to a "controller for lighting control", and the method of controlling the road surface drawing unit <NUM> by the controller <NUM> corresponds to a "control method for lighting control".

The controller <NUM> is connected to the camera <NUM>, the road surface drawing unit <NUM>, the back lamp <NUM>, the switch <NUM>, the object sensor <NUM>, and the monitor <NUM>, respectively, and controls light irradiation performed by the road surface drawing unit <NUM> according to the capturing timing, etc. by the camera <NUM>. For example, the controller <NUM> may be configured using a computer system (refer to <FIG> to be described later) having a processor (CPU: Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a storage devices such as a flash memory, an input/output interface, etc. The controller <NUM> of the present embodiment is brought into a state capable of exhibiting a predetermined function by a processor which reads and executes a program stored in advance in the storage device (or the ROM).

The camera <NUM> is installed at a predetermined position at the rear of the vehicle, for example, and captures the space behind the vehicle. Captured image data (video data) obtained by the camera <NUM> is output to the controller <NUM>. Further, the camera <NUM> outputs a signal which indicates the capturing timing to the controller <NUM>.

The road surface drawing unit <NUM> is installed at a predetermined position in the rear part of the vehicle, and operates according to a control signal provided from the controller <NUM> to irradiate the road surface behind the vehicle with a desired irradiation pattern. The irradiation pattern formed on the road surface may be fixed or variably set. As a road surface drawing unit <NUM> capable of variably setting an irradiation pattern, for example, a unit that has a plurality of LEDs (Light Emitting Diodes) arranged in two directions and can individually control the lighting and extinguishing of each light emitting diode can be used.

Here, as a road surface drawing unit <NUM> capable of variably setting an irradiation pattern, a unit configured by combining a light source bulb, a reflecting mirror, and a shielding plate may be used, or a unit that is configured by combining a liquid crystal element capable of individually controlling the light transmission state of each pixel and a light source may be used, or a unit capable of controlling timing of turning on and off a semiconductor laser such as a laser diode and timing of scanning by a scanning element may be used. Furthermore, a unit configured by combining a plurality of lamps each capable of irradiating a different fixed light distribution may be used.

The back lamp <NUM> is installed at a predetermined position in the rear part of the vehicle, and operates in response to a control signal provided by the controller <NUM> when a vehicle shift lever is designated to "reverse", thereby irradiates the space behind the vehicle (including the road surface) at a wide angle, for example.

The switch <NUM> is installed at a predetermined position near the driver's seat of the vehicle, and is used to switch the display mode of the monitor <NUM> in which the irradiation pattern drawn by the road surface drawing unit <NUM> is displayed. The switch <NUM> may be a push button switch or a toggle switch, for example. A specific example of the display mode will be described later.

The object sensor <NUM> is installed at a predetermined position in the rear part of the vehicle and detects the presence of any object in the vicinity of the rear part of the vehicle (including any objects on the road surface). The "object" here includes humans and various obstacles, for example.

The monitor <NUM> is installed at a predetermined position near the driver's seat of the vehicle and displays images captured by the camera <NUM>. As the monitor <NUM>, a liquid crystal display device, an organic EL display device, or the like can be used, for example.

Functions realized by executing the program by the controller <NUM> described above will be explained using functional blocks. The controller <NUM> is configured to include an irradiation timing setting unit <NUM> , an irradiation pattern setting unit <NUM>, and a control signal generation unit <NUM>.

The irradiation timing setting unit <NUM> sets timing of light irradiation performed by the road surface drawing unit <NUM>. In detail, by obtaining a video signal from the camera <NUM> or providing a control signal to the camera <NUM>, the irradiation timing setting unit <NUM> sets the timing of light irradiation so that the road surface drawing unit <NUM> can irradiate light at a timing that does not overlap with the capturing timing by the camera <NUM>.

The irradiation pattern setting unit <NUM> variably sets the irradiation pattern according to the operation status of the switch <NUM> or the detection status of the object detected by the object sensor <NUM>, for example, and outputs the setting to the control signal generation unit <NUM>.

The control signal generation unit <NUM> generates a control signal for realizing an irradiation pattern set by the irradiation pattern setting unit <NUM> and outputs the control signal to the road surface drawing unit <NUM>. In this embodiment, the control signal generation unit <NUM> generates a control signal so that the road surface drawing unit <NUM> performs light irradiation during a period determined according to the timing of light irradiation set by the irradiation timing setting unit <NUM>.

<FIG> is a diagram showing a configuration example of a computer system. The controller <NUM> described above can be configured using the computer system as shown in the figure, for example. A CPU (Central Processing Unit) <NUM> performs information processing by reading and executing a program <NUM> stored in a storage device <NUM>. A ROM (Read Only Memory) <NUM> stores a basic control program, etc. required for the operation of the CPU <NUM>. A RAM (a temporary memory) <NUM> temporarily stores data necessary for information processing by the CPU <NUM>. The storage device <NUM> is a large-capacity storage device for storing data, and is composed of a hard disk drive, a solid state drive, or the like. A communication device <NUM> performs processing related to data communication with other external devices. An input/output unit <NUM> is an interface for connecting with an external device. The CPU <NUM>, etc. are connected to one another via a bus so as to be able to communicate with one another.

<FIG> are diagrams schematically showing operating states of the camera <NUM> and the road surface drawing unit <NUM>. Each figure schematically shows a camera <NUM>, a road surface drawing unit <NUM>, and a back lamp <NUM>, respectively installed at the rear of the vehicle <NUM>. In the vehicle lamp system of the present embodiment, as a basic operation, the controller <NUM> performs operation control of the road surface drawing unit <NUM> so that the capturing period by the camera <NUM> and the light irradiation period by the road surface drawing unit <NUM> are complementary.

Specifically, <FIG> schematically shows a state in which the camera <NUM> captures the space behind the vehicle <NUM> including the road surface, and <FIG> schematically shows a state in which the road surface drawing unit <NUM> irradiates light of a predetermined irradiation pattern <NUM> on the road surface. In the present embodiment, during a state in which capturing by the camera <NUM> is performed (refer to <FIG>), irradiation of the irradiation pattern <NUM> on the road surface by the road surface drawing unit <NUM> does not occur. The capturing period by the camera <NUM> intermittently occurs a plurality of times.

Then, during a period between one capturing period and the next capturing period in which capturing by the camera <NUM> is not performed (non-capturing period), irradiation of irradiation pattern <NUM> by the road surface drawing unit <NUM> is performed. (Refer to <FIG>. ) The illustrated irradiation pattern <NUM> is merely an example, and a different irradiation pattern may be set depending on whether or not the object sensor <NUM> detects an object. Note that the shape of the irradiation pattern <NUM> may be fixed.

Further, in the vehicle lamp system of the present embodiment, between the state in which capturing by the camera <NUM> is performed (refer to <FIG>) and the state in which irradiation of irradiation pattern <NUM> by the road surface drawing unit <NUM> is performed (refer to <FIG>), there is a state in which neither irradiation of the irradiation pattern <NUM> nor capturing by the camera <NUM> is performed. This state is schematically shown in <FIG>. Next, each period corresponding to each state will be described in detail using a time chart.

<FIG> is a time chart for explaining a control method by the controller <NUM>. The upper part shows the operation of the road surface drawing unit <NUM>, and the lower part shows the operation of the camera <NUM>, each indicated by a belt-shaped time chart. Regarding the operation of the road surface drawing unit <NUM>, "ON" indicates a period during which light is irradiated, and the other periods (hatched periods in the figure) indicate periods during which light is not irradiated. Further, regarding the operation of the camera <NUM>, "ON" indicates a capturing period, and the other periods (hatched periods in the figure) indicate non-capturing periods.

The camera <NUM> is for capturing moving images, and as shown in <FIG>, captures images at a fixed cycle Tc. This cycle Tc is determined by the standard adopted by the camera <NUM>, and is a length corresponding to <NUM> fps in the case of a PAL standard composite signal, and is a length corresponding to <NUM> fps in the case of an NTSC standard composite signal. A capturing period ts which arrives every cycle Tc is a period required to acquire an image of one frame, and can be expressed as a shutter open period or an exposure period. It is preferable that the length of the capturing period ts is set to <NUM>/<NUM> or less of the cycle Tc. For example, in the case of an NTSC standard composite signal, it can be said that it is preferable to set to <NUM>/<NUM> seconds or less.

The road surface drawing unit <NUM> irradiates a predetermined irradiation pattern <NUM> (refer to <FIG>) under the control of the controller <NUM>, and as shown in <FIG>, the road surface drawing unit <NUM> irradiates light during a non-capturing period which does not overlap with the capturing period ts of the camera <NUM>. It is preferable that light irradiation period tm (period indicated as "ON" in the figure) at this time is set to a longer time as long as it does not overlap with the capturing period ts. This is because the brightness of the irradiation pattern <NUM> can be further increased. The light irradiation period tm is set by the irradiation timing setting unit <NUM> of the controller <NUM>.

Since the light irradiation period tm arrives every cycle Tc in synchronization with the capturing timing of the camera <NUM>, for example, if cycle Tc is an NTSC standard composite signal and if the length corresponds to <NUM> fps (<NUM>/<NUM> second), then the cycle at which the light irradiation period tm arrives becomes <NUM>. At <NUM>, human eyes can perceive the irradiation pattern <NUM> irradiated from the road surface drawing unit <NUM> (refer to <FIG>) as being continuously lit.

Between the light irradiation period tm and the capturing period ts, in other words, before and after the capturing period ts, there is provided a period tn during which neither the capturing by the camera <NUM> nor the irradiation of the irradiation pattern <NUM> is performed. As a result, since there is always a state in which the road surface drawing unit <NUM> does not irradiate on the road surface before and after the capturing by the camera <NUM>, it is possible to more reliably prevent the camera <NUM> from capturing the road surface during a state in which the road surface is irradiated with irradiation pattern <NUM>. The length of period tn is preferably as short as possible as long as the above objective can be achieved. This is to ensure a longer light irradiation period tm.

In <FIG>, the state in which capturing is performed by the camera <NUM> is defined as "state <NUM>", the state in which light irradiation is performed by the road surface drawing unit <NUM> is defined as "state <NUM>", and the state in which neither capturing by the camera <NUM> nor light irradiation of irradiation pattern <NUM> is performed is defined as "state <NUM>", which is respectively indicated as (<NUM>), (<NUM>), and (<NUM>) in <FIG>. As shown in the figure, each state transitions in the order of state <NUM>, state <NUM>, state <NUM>, state <NUM>, state <NUM>, state <NUM>,. In detail, state <NUM> is repeated at cycle Tc, and state <NUM> exists before and after state <NUM>. Further, state <NUM> is also repeated at cycle Tc, and state <NUM> also exists before and after state <NUM>. State <NUM> before state <NUM> and state <NUM> after state <NUM> are common, and state <NUM> after state <NUM> and state <NUM> before state <NUM> are common.

Here, irradiation mode of irradiation pattern <NUM> during light irradiation period tm may be continuous irradiation or pulse irradiation. In the case of pulse irradiation, for example, pulse irradiation at a frequency of about <NUM> to <NUM> is preferable. By applying pulse irradiation, an increase or decrease in the illuminance of the irradiation pattern <NUM> can be controlled by the pulse width.

<FIG> is a time chart for explaining a modified example of a control method by the controller <NUM>. The basic control method of this example is as described above with reference to <FIG>, therefore, only the differences will be described in detail. In the control method of this modified example, basically as described above, the road surface drawing unit <NUM> is controlled by the controller <NUM> so that transitions are made in the order of state <NUM>, state <NUM>, state <NUM>, state <NUM>, state <NUM>, state <NUM>,.

Furthermore, in this modified example, the road surface drawing unit <NUM> is controlled so that capturing period ts and light irradiation period tm by the the road surface drawing unit <NUM> overlap once every multiple times (for example, five times) of the capturing period ts by the camera <NUM>. Such a state in which both the irradiation of irradiation pattern <NUM> and capturing by the camera <NUM> are performed is defined as "state <NUM>" and is indicated by (<NUM>) in the figure. By causing this state <NUM> to occur once every multiple times of capturing period ts, the camera <NUM> can intermittently capture the irradiation pattern <NUM> (refer to <FIG>) on the road surface. As a result, the monitor <NUM> intermittently displays the predetermined irradiation pattern <NUM> formed by the road surface drawing unit <NUM>. Depending on the occurrence cycle of state <NUM>, the human eye perceives the irradiation pattern <NUM> displayed on the monitor <NUM> as a blinking display.

Whether or not to display such irradiation pattern <NUM> can be selected using the switch <NUM> described above, for example. That is, by setting the timing of light irradiation of the road surface drawing unit <NUM> by the irradiation timing setting unit <NUM> according to the state of the switch <NUM>, state <NUM> can be generated between state <NUM> and the following state <NUM>. Here, state <NUM> may be generated when an object is detected by the object sensor <NUM>. As a result, the presence of an object can be notified to the driver through the blinking display.

Further, brightness of irradiation pattern <NUM> during the period in which state <NUM> is generated may be reduced to about <NUM>/<NUM>, for example. As a result, white clipping can be suppressed. Dimming of the irradiation pattern <NUM> can be achieved by reducing the pulse width of the ON period if control method of the road surface drawing unit <NUM> is pulse width control, or can be achieved by lowering the current value if control method of the unit is current control.

According to the above-described embodiments, when a road surface on which an irradiation pattern is formed is captured by a camera, it is possible to avoid so-called white clipping and to grasp the road surface condition more reliably. Further, in the aspect of intermittently generating a state in which both the irradiation of irradiation pattern <NUM> and capturing by the camera <NUM> are performed (state <NUM>), it is possible to achieve both grasping the road surface condition and visual recognition of irradiation pattern <NUM> drawn on the road surface.

Here, it should be noted that the present teachings are not limited to the content of the above-described embodiments, and can be implemented in various modifications within the scope of the claims. In an example not being part of the present invention, the timing of light irradiation of the back lamp <NUM> in the above-described embodiment may be synchronized with the capturing period of the camera <NUM>. Specifically, as shown in <FIG>, when capturing period ts of the camera <NUM> arrives at cycle Tc, the back lamp <NUM> can also be pulse-controlled so as to irradiate light in synchronization with the cycle Tc. As a result, since light irradiation by the back lamp <NUM> is performed in correspondence with the capturing period ts of the camera <NUM>, the image captured by the camera <NUM> and displayed on the monitor <NUM> can be made brighter.

Claim 1:
A controller (<NUM>) for lighting control installed in a vehicle (<NUM>) that is equipped with a camera (<NUM>) that captures the surroundings of the vehicle (<NUM>), a monitor (<NUM>) that displays images captured by the camera, an irradiation unit (<NUM>) capable of irradiating an irradiation pattern (<NUM>) on a road surface within a range that can be captured by the camera (<NUM>), and an object sensor (<NUM>), in which the controller (<NUM>) is adapted to perform operation control of the irradiation unit (<NUM>), wherein the controller (<NUM>) is adapted to perform operation control of the irradiation unit so that it prevents the irradiation unit (<NUM>) from performing irradiation of said irradiation pattern (<NUM>) during each intermittently occurring capturing period of the camera, and causes the irradiation unit (<NUM>) to irradiate said irradiation pattern during a non-capturing period between the capturing periods, and
wherein, when the presence of an object is detected by the object sensor (<NUM>), the controller (<NUM>) is adapted to cause the light irradiation unit (<NUM>) to perform light irradiation within a capturing period at a rate of once every multiple time of capturing period.