Action camera with capability of capturing images in daylight and infrared

The action camera has a housing, a lens, and an image sensor located in a light path from the lens. A filter is operable to move between first and second positions, with the first position located in the light path and the second position located out of the light path. An actuator moves the filter between the first and second positions. The actuator includes an electromagnet and a magnet. One of the electromagnet and the magnet is fixed relative to the light path, while the other of the electromagnet and the magnet is movable relative to the light path and is coupled to the filter. The magnet has poles that interact with the poles of the electromagnet. As the electromagnet is energized, the magnet rotates. The polarity of the electromagnet is reversed in order to reverse the rotation of the magnet. The camera is also provided with a light source. When the light source is activated, then the filter is moved accordingly. The actuator is small and consumes little electrical power.

FIELD OF THE INVENTION

The present invention relates to portable cameras that can capture images in both daylight and infrared conditions.

BACKGROUND OF THE INVENTION

Action cameras are small, lightweight portable cameras used to take video, still pictures or both. Action cameras are used in action sports, such as hunting, BMX (bicycle motorcross), snow skiing or snowboarding, surfing, car racing, skydiving, etc. The camera is typically mounted so as to point ahead where the operator is going. For example, in bicycling, the camera may be mounted to the handlebars of the bicycle. In snowboarding, the camera may be mounted to the helmet of the snowboarder. In hunting, the camera may be mounted to either the hunter's head or to the hunter's gun.

While many action cameras operate in daylight conditions, there are instances where artificial lighting is desired to supplement low natural light for darkness. For example, hunters hunt at dawn and dusk. In order to avoid scaring wildlife away, infrared lighting is preferred to white light. Therefore, equipping an action camera with infrared lighting is desirable.

Digital cameras use an image sensor to capture the image, whether video or still. Most image sensors react differently to white, or visible, light than to infrared light. In order to compensate, when the image sensor is configured for white light, or daylight, an infrared cut filter is located in-line with the image sensor (between the lens and the image sensor). The infrared cut filter filters out infrared light from the image sensor. When the image sensor is configured for infrared or night conditions, the infrared cut filter is removed from the path of light and a clear, or infrared pass, filter can be put in-line with the image sensor.

In an action camera, several factors, such as weight and power consumption, come in to play when designing a system to remove the infrared cut filter relative to the image sensor.

SUMMARY OF THE INVENTION

The present invention provides a portable camera that comprises a housing, a lens, an image sensor, a filter, an actuator and a power source. The image sensor is located in a light path from the lens. The filter is operable to move between a first position located in the light path and a second position located out of the light path. The actuator comprises an electromagnet and a magnet. One of the electromagnet and the magnet is fixed relative to the light path while the other of the electromagnet and the magnet is movable relative to the light path and is coupled to the filter. The magnet has at least first, second and third poles, with the first and third poles having the same polarity and the second pole being opposite in polarity from the first and third poles and intermediate between the first and third poles. The electromagnet has fourth and fifth poles that are adjacent to the magnet. The magnet second pole is attracted to either one of the fourth and fifth poles of the electromagnet, depending on the polarity of the electromagnet. The power source is connected to the electromagnet. The power source provides electrical power to the electromagnet. The power source is capable of changing the polarity of the electrical power provided to the electromagnet so as to change the polarity of the fourth and fifth poles of the electromagnet.

In accordance with one aspect, the camera further comprises a filter holder. The filter holder comprises a filter part that is coupled to the filter and a support arm. The support arm has a pivot point. The other of the electromagnet and the magnet that is movable moves the support arm and the filter part about the pivot point.

In accordance with another aspect of the camera, the filter comprises a first filter. There is a second filter that is movable in and out of the light path by the actuator.

In accordance with another aspect, the camera comprises first and second filter holders, with each filter holder comprising a filter part that is coupled to the respective first or second filters, and a support arm. Each support arm has a pivot point. The other of the electromagnet and the magnet that is movable moves the support arm and the filter part of the first filter holder about the first filter holder pivot point in a first direction and moves the support arm in the filter part of the second filter holder about the second filter holder pivot point in a direction that is opposite to the first direction.

In accordance with another aspect, the camera has the other of the electromagnet or the magnet that is movable engage the support arm of the first filter holder at a first filter location that is between the first filter and the respective pivot point, and engages the support arm of the second filter holder at a second filter location that is interposed between the second filter and the second filter location.

In accordance with another aspect, the electromagnet is fixed and the magnet rotates.

In accordance with another aspect, the electromagnet is “U” shaped. In accordance with another aspect, the magnet rotates less than 90 degrees.

In accordance with another aspect, the magnet has a finger that engages a slot on a support arm that is coupled to the filter. The support arm rotates about a pivot point.

In accordance with still another aspect, the camera further comprises a light source and a processor. The light source provides light within a field of view of the lens. The processor controls the position of the filter in the light path. The processor moves the filter with respect to the light path when the light source is illuminated.

In accordance with still another aspect, the light source is an infrared light source and the filter is an infrared cut filter, wherein when the light source is illuminated, the infrared cut filter is located out of the light path.

In accordance with still another aspect of the portable camera, the filter comprises a first filter. A second filter is also provided that is movable in and out of the light path by the actuator. First and second filter holders are provided, with each filter holder comprising a filter part that is coupled to the respective first or second filters, as well as a support arm. Each support arm has a pivot point. The other of the electromagnet and the magnet that is movable moves the support arm and the filter part of the first filter holder about the first filter holder pivot point in a first direction and moves the support arm in the filter part of the second filter holder about the second filter holder pivot point in a direction that is opposite of the first direction. The other of the electromagnet or magnet is movable and engages the support arm in the first filter holder at a first filter location that is between the first filter and the respective pivot point and engages the support arm of the second filter holder at a second filter location that is interposed between the second filter and the second filter location. The electromagnet is fixed and the magnet rotates. The electromagnet is “U” shaped. The magnet rotates less than 90 degrees. The magnet has a finger that engages the slot on a support arm that is coupled to the filter. The support arm rotates about a pivot point.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The action camera11is shown inFIGS. 1 and 2. The camera is small, lightweight and portable. It can be carried in the hand or mounted to a person (such as a helmet) or to a piece of equipment (such as a bicycle). The camera11can be operated to take video or still pictures. The camera described herein is a digital camera, although the camera could be a film camera.

The camera is particularly adapted to take pictures in normal lighting conditions (such as daylight) as well as in low light conditions (such as night). The camera has one or more filters that are moved in and out of the light path between the camera lens and the image sensor. The filters optimize the light for normal lighting conditions and optimize the light for low lighting conditions.

Because of the small size and limited power supply, the camera does not use a conventional motor to change the filters. Instead, the camera uses magnets.

The camera11will now be described in more detail. The camera includes a housing13, electronics15(seeFIG. 3) and a lens17.

The housing13has a front end19and a rear end21. The front end19contains the lens17and a light source23(FIG. 1shows only a few of the light sources23). InFIG. 2, which shows the rear end21of the camera, a cover is shown as removed to allow viewing of components. The rear end21contains a cavity for a battery25(shown behind an inner cover, which inner cover is optional), one or more input/output ports27, a memory card receptacle29(shown with a removable memory card), an indicator light31and a port33for an external power supply or charger (shown with a cover in place). The housing also has a user interface in the form of a display35, keys or buttons37and a record button39. The housing has a mount41on one side, which side is free of the user interface. The mount41is used to mount the camera to other apparatuses such as a helmet or a bicycle.

FIG. 3shows a block diagram of the electronics15and the lens17, which are contained in the housing13. A central processing unit (CPU)43is provided. In the preferred embodiment, the CPU incorporates features of a video processor. An image sensor45provides inputs to the CPU43. The image sensor45can be a CMOS or CCD type sensor. The image sensor is located behind the lens17. A light path47extends from the lens17to the image sensor45. The image sensor captures the image and provides it to the CPU for processing. The CPU43has a clock49.

Memory51is connected to the CPU. The memory includes nonvolatile memory and may include volatile memory. In addition, removable memory devices, such as memory cards, can be used. Memory cards are referred to as external memory. The memory card is inserted into the slot29and is removable.

The camera can take pictures or video in daylight and also in lowlight conditions using a light source. In the preferred embodiment, the light source is infrared (1K) provided by LED's23(light emitting diodes). The lights23are powered by a driver55which is connected to the CPU43. If the camera is taking video, then the lights stay on during filming. If the camera is taking still pictures, then the lights illuminate long enough to capture the picture.

Filters57are removably provided between the lens17and the image sensor45, in the light path47. In the preferred embodiment, there are two filters. One filter is an infrared cut filter, which blocks infrared light. The infrared cut filter is located in the light path for daylight filming. The other filter is an infrared pass filter and allows infrared light to reach the image sensor. The infrared pass filter is used during low light filming and when the infrared lights53are illuminated.

FIG. 4shows the lens filters. The filters are located in a lens mount housing59, which housing has an inner portion60and an outer portion61. The outer portion61has a cylindrical bore63for holding the lens17(although the lens17is shown inFIG. 4with no curvature on the front side, it is understood that the lens may have the appropriate curvature or shape). The inner portion59has an opening65aligned with the lens17and in-line with the light path47. The image sensor45(not shown inFIG. 4) is located adjacent to the opening65. The inner and outer portions60,61couple together and have a cavity therein for receiving the filters57.

The filters57are moved in and out of the light path47by a filter motor67(seeFIGS. 3 and 4). The filter motor is driven by a driver69which in turn is connected to the CPU43.

Because of the small size and light weight of the action camera, the filter motor67does not use a conventional electric rotary motor with a stator and rotor and gears. The filter motor67is shown inFIG. 4and includes a magnet71and an electromagnetic73. One of the magnet and the electromagnet moves while the other of the magnet and the electromagnet remains stationary with respect to the lens mount housing59. The moving element moves the filters57in and out of the light path47. In the preferred embodiment, the magnet71rotates while the electromagnetic73is fixed.

Referring toFIGS. 4-5B, the electromagnet73has a “U” shaped magnetizable member75, such as made of a ferromagnetic material. A coil77of wire is located around a portion of the “U” shaped member. The coil has pins79A,79B. The free ends of the “U” shaped member form the poles81of the electromagnet. When a voltage is applied to the pins, the electromagnet becomes magnetized. The polarity of the magnetic poles changes if the voltage polarity applied to the pins changes. For example, if the voltage polarity is pin79A (+), pin79B (−), the magnetic poles are, using the orientation shown inFIGS. 5A and 5B, top pole (N) and bottom pole (S). The poles reverse if the voltage polarity on the pins79A,79B reverses.

The magnet71is ring shaped or disc shaped. The polarity of the magnet71is shown inFIGS. 5A and 5B, where the adjacent north and south poles are located on the outside diameter and are approximately 90 degrees apart. This type of magnet has multi-poles on the circumference. Alternatively, the magnet could be radially magnetized with multi-poles wherein opposite poles are located on the inside diameter of the ring shaped magnet.

A shaft83extends axially through the magnet71. Coupled to the magnet71is a disk85. A projection extends radially from the disk. A finger87then extends from the projection, which finger is parallel to the shaft83. The finger87is thus offset from the shaft83.

The electromagnet and magnet are mounted to the lens mount housing59by way of an electromagnet cover89. The cover89fixes the electromagnet73in place relative to the lens mount housing. The cover89has a circular inner recess91for receiving the magnet71and an inner recess93for receiving the electromagnet. The pins79A,79B extend out of the cover. The cover89secures the electromagnet73and the magnet in place and allows the magnet71to rotate about its shaft83. The magnet is located adjacent to the poles81of the electromagnet. As the polarity of the electromagnet poles81change, the magnet71will rotate. This is illustrated inFIGS. 5A and 5Bwhere, using the orientation shown, the bottom electromagnet pole81is N and the top electromagnet pole is S, the magnet rotates clockwise fromFIG. 5AtoFIG. 5B. To make the magnet rotate counterclockwise, the polarity of the electromagnet is reversed to the top pole N and bottom pole S.

The magnet71moves filter assemblies95A,95B which contain the filters57. Each filter assembly includes one of the filters57and a filter holder97. The filter holder97has a main part99and a supporting arm101that extends from the main part. Each main part99has two sides, namely a smooth side103and filter side105. The main part also has an opening107for allowing light to pass therethrough. The filter57is coupled to the main part99on the filter side105. The filter holders97are arranged so that the smooth sides103are adjacent to each other. This minimizes scratching of the filters.

Each supporting arm101has two holes located along the length of the arm. One hole is a slot109that receives the finger87from the magnet motor. The other hole111, or pivot hole, receives a shaft or post that is fixed to the lens mounting housing59. The location of the pivot hole is different on the two filter assemblies. On a first filter assembly95A, the pivot hole111is between the slot109and the respective filter57. On a second filter assembly95B, the slot109is between the pivot hole111and the respective filter. The filter assemblies move by pivoting about posts or pins located in the respective pivot holes111. The post113for one filter assembly95A projects from a first wall114of the lens mounting housing and is received by the pivot hole of the one filter assembly support arm. The post113does not contact the other filter assembly. The post115for the other filter assembly95B projects from a second wall116of the lens mounting housing and is received by the pivot hole of the second filter housing. As shown inFIG. 4, the second wall forms a shelf relative to the first wall. The post115for the second filter assembly is roughly coaxial with the magnet shaft83. The magnet finger87passes through the first wall of the lens mount housing by way of a slot117. The slot is curved, as the finger moves along the curved path when the magnet rotates.

FIGS. 5A,5B,6A and6B show the movement of the filter assemblies95.FIGS. 5A and 5Bare taken from the side of the image sensor looking toward the lens (or left to right referring to the orientation ofFIG. 4) and do not show the housing.FIGS. 6A and 6Bare taken from the opposite, or lens, side. The filter positions inFIG. 5Acorrespond to that ofFIG. 6Aand the filter positions ofFIG. 5Bcorrespond to that ofFIG. 6B. The filter positions inFIGS. 4 and 6Bcorrespond to each other. InFIGS. 6A and 6B, the outer portion of the lens mount housing has been removed. InFIG. 5A, the second filter assembly95B is in the light path (the light path is located below the electromagnet73in the figures), while the first filter assembly95A is out of the light path. To reverse this arrangement, the electromagnet73polarity is reversed and the magnet71rotates clockwise (fromFIGS. 5B to 5A, counterclockwise inFIG. 6A) to the position shown inFIGS. 5B and 6B. As the magnet71rotates, the magnet finger87moves the first filter assembly95A counterclockwise (inFIG. 5A; clockwise inFIG. 6A) about its pivot hole to a position in-line with the light path, and moves the second filter assembly95B clockwise (inFIG. 5A, counterclockwise inFIG. 6A) about its pivot point to a position out of the light path. InFIGS. 5A and 5B, the pivot hole for the second filter assembly is located behind the magnet and is approximately the same position as the magnet shaft and is in approximately the same position as the magnet shaft. Conversely, to change the filters, the polarity of the electromagnet is reversed, wherein the magnet rotates counterclockwise (fromFIGS. 5B to 5A; counterclockwise fromFIGS. 6B to 6A), the first filter assembly pivots clockwise and the second filter assembly pivots counterclockwise.

As shown inFIGS. 6A and 6B, the rotational movement of the filter assembly is limited by the side walls of the lens mount housing59, which side walls act as stops. InFIG. 6A, the counterclockwise movement of the first filter assembly95A is stopped by the side wall at119, while the clockwise movement of the second filter assembly95B is stopped by a projection120from the side wall. As shown inFIG. 6B, the clockwise movement of the first filter assembly is stopped by the side wall at121, while the counterclockwise movement of the second filter assembly is stopped by the side wall at122.

Referring again toFIG. 3, the other electronic components will be discussed. The camera has a user interface that includes a display35and various buttons or keys37,39. The display is of the LCD (liquid crystal display) type and provides information on time and date, on mode of operation (video mode or still images mode), on type of video (high definition I-ID or WGVA), if still pictures are taken, then normal operation (one picture per shutter button operation) or plural pictures per shutter button operation, zoom (whether any zoom is employed and if so the amount) and a delete operation. In addition, the display indicates the level of battery charge and the remaining time of video capability or number of remaining still pictures which is capable of being stored by the memory. The display is connected to the CPU by a driver123. User input buttons37, when used in conjunction with the display35, allow information to be provided to the camera and to the camera user. Also, the record button39, or shutter button, when pressed, starts recording or takes a still image and when pressed again stops video recording. If the camera is in the still picture mode, the record button operates as a shutter release.

The CPU43is also connected to an indicator or status light31. The status light illuminates when the camera is recording. The CPU is connected to the power supply25and to the input/output port or ports. In the preferred embodiment, the input/output ports are a USB port and HDMI port.

An audio digital signal processor (DSP)125is connected to the CPU. The audio DSP is connected to a microphone127which provides a sound input and to a speaker129which provides a sound output.

The operation of the camera is simple. To turn the camera on, the user presses the appropriate button; the display then turns on. The user can make any programming changes to the operation of the camera with the user interface and the display. The record button is pressed to record video or take a still picture.

The CPU performs many functions, such as taking image data from the image sensor, processing the image data and writing the image data to memory, as well as writing any sound data to memory. The audio digital signal processor125processes sound received from the microphone127. The CPU also provides information to the display and accepts user inputs, as well as controls operation of the image sensor, the infrared lights53and the filters57. In addition, the camera automatically senses the light level and determines if the filters need be changed and if the lights53turned on.

FIG. 7is a flow chart illustrating this operation. Initially, the camera is in stand by or default mode, wherein the infrared cut filter is in the light path, step131. The camera is thus configured for daylight operation. In step133, the camera determines if the record button39has been pressed. If NO, then step131is repeated. If YES, the camera determines if the exposure value (EV) is above a predetermined threshold value or constant, step135. The exposure value is a product of the exposure time and the iris aperture that is measured by the image sensor45. If the exposure time is above the predetermined threshold, the lighting is considered adequate and recording starts, step137. The camera then determines if the record button39has been pressed again, step139. If YES, then the recording stops and the camera returns to standby mode, step131. If the recording is not ended, NO, in step139, then the camera remeasures the exposure value, step135, to determine if the lighting conditions have changed during recording.

If the lighting conditions are too low so that the result of step135is NO, then the filters are changed out. In step141, the filter motor67is operated in order to remove the infrared cut filter from the light path and substitute the infrared pass filter. The driver69sends a pulse to the filter motor of sufficient duration and polarity to change the position of the filters. The pulse is then discontinued in order to conserve power. The filters remain in their positions and need not be held in position with the motor67. In addition, the infrared lights23are turned on. In step143, recording starts. In step145, the end of recording is monitored. If recording continues, then this step merely loops. If recording ends, then in step147, the infrared cut filter is relocated back in-line in the light path and the infrared lights are turned off. To move the filters, the driver69sends a pulse of opposite polarity than the previous pulse. The camera then returns to step131and standby status.

The filter motor57provides an actuator to move the filters in and out of the light path, which motor is small and useful for a portable camera. In addition, the filter motor consumes little electrical power.

The foregoing disclosure and showings made in the drawings are merely illustrative of the principles of this invention and are not to be interpreted in a limiting sense.