Positioning system for a combiner in a head up display

A combiner positioning system (300) for a heads-up display (100). The positioning system (300) is arranged on a frame (302) including a base plate (334). A movable carrier (306) is provided for supporting a combiner (106) within the frame. The carrier (306) is movable between a first end of the frame, where the combiner (106) is in a retracted position (storage position), to a second end where the combiner is in a fully extended position (display position).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns electromechanical positioning systems, and more particularly an electromechanical positioning system for a mirror in a head up display.

2. Description of Related Art

A head-up display or HUD is a transparent display panel that presents information to a user without requiring him to look away from a preferred viewing direction. For example, a driver can view traffic and the road in front of the vehicle through the transparent panel of the HUD. A typical HUD includes a combiner, a projector, and a video data source such as a computer. The combiner is the transparent panel that is located in front of the person observing the display. The combiner usually includes one or more optical coatings that reflect only those specific wavelengths of monochromatic light that are projected by the HUD projector. The combiner can be thought of as a semi-transparent mirror. The HUD projector is usually mounted above or below the combiner. Images containing graphics or data are projected by the projector toward the combiner, which then projects the images toward the user.

Combiner positioning mechanisms for a HUD, which can move the combiner between a storage position and an operating position, are known in the art. For example, one such combiner is disclosed in PCT Publication No. WO 2007/057608 A1. Such positioning mechanisms have stored the combiner in a protected chassis when in a storage position. The combiner is mounted on a movable support that is displaceable between a rest position and a display position. The blade is retracted when the movable support is in the rest position and the combiner is extended from the chassis when the movable support is in the display position.

Still, combiner positioning mechanisms require careful consideration to ensure the performance in all kinds of environmental conditions such as high humidity, extreme temperatures, and the presence of contaminants that can cause corrosion. In such systems, careful choice of materials and design are necessary to provide smooth motion.

Repeatable positional accuracy is also important for combiner positioning mechanisms because an improperly positioned combiner will not function properly in a HUD system. Such positional accuracy can be achieved using high precision parts that are manufactured and maintained to very close tolerances. However, the need for such close tolerances has the undesirable effect of increasing the manufacture and maintenance expense associated with the positioning mechanism.

Another key design consideration relates to vibration. A mobile HUD system must have a high resistance to vibration in order to provide a stable image for the user. Failure to control vibration associated with the combiner in particular can result in a display that is irritating for the viewer and unpleasant to use over extended periods. Accordingly, a positioning system for a combiner in a HUD should have a high stability and a high natural frequency.

SUMMARY OF THE INVENTION

The invention concerns a combiner positioning system for a heads-up display. The positioning system is arranged on a frame including a base plate. A movable carrier is provided for supporting the combiner within the frame. The carrier is movable between a first end of the frame, where the combiner is in a retracted position (storage position), to a second end where the combiner is in a fully extended position (display position).

A parking member is mounted to the frame opposed from the base plate. The parking member is spaced apart a predetermined distance from the base plate. The carrier, when in the display position; is transported and rotated to a position between the parking member and the base plate. The carrier is resiliently grasped or clamped between the parking member and the base plate by using a force applied by a spring. A raised ridge is provided on a portion of the base plate as an aid to clamping or grasping the carrier in the display position.

The parking member includes a recess for receiving at least one pin provided on the carrier, the pin defines a pivot axis of the carrier such that the carrier is rotatable about the pivot axis when it is clamped between the base plate and the parking member. With the foregoing arrangement, the carrier is responsive to a force applied transverse to the pivot axis for making small changes to adjust the angular orientation of the combiner after it has been moved to the display position. A friction reducing member is disposed on a portion of the carrier adjacent to the base plate. The friction reducing member can be a wheel or a low friction material which is selected to slide along the surface of the base plate or upon some intervening low friction layer disposed on the base plate.

Sidewalls are provided arranged generally transverse to the base plate. A cam is positioned adjacent to an interior side of each side wall and extending along at least a portion of a length of the frame. The cams are arranged such that a distance between the base plate and the cam increases from a first end of the frame to an opposing second end of the frame. A gear rotatably mounted to each opposing side of the carrier engages a respective one of the cams. The cams guide the carrier from the storage position at the first end of the frame to the display position at the second end. The cam provides a guide or track for transporting the carrier from one position to another within the frame, and concurrently rotating the carrier from a storage orientation (in which the combiner is stored) to a display orientation (in which the combiner is ready for use).

A drive system is provided for automatically moving the carrier from the storage position to the display position. The drive system includes a screw spindle coupled to a motor, and a nut system threaded on the screw spindle. The spindle is generally aligned with a length of the cam. The nut system is operatively coupled to the carrier for urging the carrier along the length of the frame when the spindle is rotated by the motor. The same drive system is used to also provide small angular adjustments to the carrier when the combiner is in the display position. Opposing flanges are provided on the carrier. An edge of the combiner is clamped between the opposing flanges for securing the combiner. A layer of adhesive is disposed between the combiner and at least one of the flanges.

DETAILED DESCRIPTION

The invention concerns a positioning system for a combiner used in a head up display (HUD). The basic features and operation of the positioning system100are best understood with reference toFIGS. 1A and 1B. As illustrated therein, the positioning system includes a chassis102. In a fully retracted position (not shown) the combiner106can be fully retracted within the protective confines of the chassis102. The fully retracted position is also referred to herein as the storage position. The protective covering provided by the walls of the chassis102protects the combiner106from contamination, dust, and impacts. When in use, the combiner106is extended from an interior of the chassis through slot108or other suitable opening formed in the chassis. Tabs104are provided for mounting the positioning system in a vehicle or other structure.

FIG. 1Ashows the combiner partially extended from the chassis102.FIG. 1Bshows the combiner106in a fully extended position (also referred to herein as the display position) where it is ready for use. A positioning mechanism provided within the chassis102is arranged to automatically move the combiner from its fully retracted position, where it is stored, to the fully extended position. It can be observed inFIGS. 1A and 1Bthat, as the combiner moves from the retracted to the extended position, it is transported and rotated from a storage orientation through an angle of approximately 90 degrees, to a display orientation. This arrangement advantageously allows the combiner to be used in the display orientation as needed, but still allows it to be stored in a storage orientation for protection and compactness of design. When the combiner is in the fully extended position for display, the combiner can be adjusted in minute increments to achieve proper function.

Combiners used in HUD devices are well known in the art and therefore will not be described in detail. However, it should be understood that the combiner106can be any type of combiner designed for operation in a HUD system that is now known or may be known in the future. For example, the combiner106can be formed of a generally planar transparent substrate that includes one or more optical coatings. The substrate can include, without limitation, transparent polymers and/or glass. The optical coatings are advantageously selected to reflect one or more specific wavelengths of monochromatic light.

Those skilled in the art will appreciate that the combiner positioning system100can be used in conjunction with a complete HUD system. In such a configuration, the HUD system can also include a light projector202, a controller204, and a video generator206. Images that are projected by light projector202are reflected by the combiner toward an observer. The video generator206is coupled to the light projector202and is used to generate images to be projected on the combiner106. The images can include text, graphics or a combination of the two.

The controller204is designed to control and coordinate the operation of the combiner positioning system100, the video generator206and the projector202. For example, the controller204can cause the combiner to be extended from the chassis102when the HUD is in use, and retracted into the chassis102when the system is not in use. The controller can also selectively apply power and control signals to the video generator206and the projector202to cause images to be projected toward the combiner106when the system is in use.

Those skilled in the art will appreciate that the controller can be implemented in a variety of different ways. For example, the controller204can be a programmable logic array, a microprocessor, or a general purpose computer programmed with a set of instructions. Still, the invention is not limited in this regard. Any suitable combination of components known now or in the future can be used for implementing a HUD system for use with the combiner positioning system100described herein.

Referring now toFIG. 2, there is shown a perspective view of a positioning mechanism300which is disposed within the chassis102. InFIG. 2, the combiner106is shown in the fully extended or display position corresponding toFIG. 1B. The positioning mechanism300includes a frame302on which the combiner106is supported in a horizontal storage orientation when fully retracted, and in a vertical display orientation when fully extended. The frame includes a base plate334and side wall portions323,325. The side wall portions323,325extend in a direction generally transverse to the base plate334. The side wall portions323,325can be integrated with the frame302, or can be attached to and/or supported by the frame302.

The movement and rotation of the combiner106relative to the frame302can be generally understood with reference toFIGS. 3-6. The combiner106is shown in its fully retracted positioning inFIG. 3. The combiner106is shown in various intermediate stages of extension inFIGS. 4-5, and is shown in its fully extended position inFIG. 6.

The features of the positioning mechanism300shall now be described in further detail. As shown inFIG. 2, the combiner106is securely attached to a carrier306to form a unit. The carrier306can be secured to the combiner106by any suitable means. In a preferred embodiment, however, the carrier306is comprised of a first and second flange308,309each of which are formed of relatively stiff material. The stiff material can be any suitable material. For example, a metal or rigid plastic polymer can be used for this purpose without limitation. According to a preferred embodiment, the stiff material can be a plastic material reinforced with glass fiber. However, the invention is not limited in this regard. A face of flanges308,309is generally formed with a profile which closely conforms to the profile of the combiner. For example, the faces of the flanges can have a planar or a slightly concave profile to match the contour of an edge of the combiner which is disposed between the flanges.

The first flange308can be integral part of the carrier306. However, it can also be provided as a separate assembly that is secured to the carrier306by suitable means. An edge portion307of combiner106is advantageously secured or clamped between the first and second flange308,309. This arrangement helps prevent bending, flexing and/or physical distortion of the combiner during thermal cycling of the device and during periods of temperature stress. As used herein, temperature stress refers to extreme high or low temperatures that the combiner and positioning mechanism may be exposed to during use or storage.

According to a preferred embodiment, a layer of adhesive354is advantageously disposed between the edge portion307of combiner306and one or more of the flanges308,309. Use of adhesive in this context is advantageous because it increases the stiffness/natural frequency of the mirror. The adhesive also minimized problems with clamping of plastic combiners used at high temperatures, where material creep can cause a loss of pretension. Finally, vibration energy can be absorbed and/or damped by selecting the proper adhesive. Liquid adhesives are presently preferred for this purpose. However, the invention is not limited in this regard.

According to an embodiment of the invention, it is preferred that the adhesive354is disposed between the combiner306and each of the flanges308,309. Use of adhesive354on both sides of the combiner in this way is advantageous to prevent thermal variations from causing substantial distortion of the combiner. The adhesive prevents the combiner from deforming by forcing it to structurally conform to the shape of the flanges, even when the thermal variations might otherwise cause a distortion in the combiner.

The flanges308,309can also be secured to the combiner106by additional or alternative means. For example, threaded members310can be provided which extend through the first flange and engage a threaded bore formed in the second flange.

The carrier306moves from a first end324of the frame302(as shown inFIG. 3) to a second opposing end326of the frame (as shown inFIG. 6) when the combiner transitions from its fully retracted position to its fully extended position. A motor304is provided in order to cause the necessary movement of the carrier306and combiner106. Any suitable motor can be used for this purpose provided that it is configured for clockwise and counterclockwise rotation responsive to input control signals. The motor304has an output drive shaft (not shown) operatively attached to a screw spindle312which is threaded along its length. The screw spindle is journaled in a bearing314disposed at an end of the screw spindle opposed from the motor304. A nut system316is threaded on the screw spindle312such that turning the screw spindle312results in a horizontal movement of the nut system316along the length of the screw spindle (y-axis) as shown inFIGS. 3-6. The nut system316has a bearing317which engages the carrier306, and urges the carrier along in a direction aligned with the y-axis when the screw spindle is rotated.

Adjacent and parallel to the spindle screw312there is provided a guide rod328which is provided for guiding the carrier306. The guide rod328is positioned within a bore319that is formed in the bearing319. With the foregoing arrangement, the bearing319can slide along the length of the guide rod328to control the motion of the carrier306as the nut system316is moved by the screw spindle312. The movement direction of the nut system316along the y-axis defined by the screw spindle is determined by the clockwise or counter-clockwise rotation direction of the screw spindle.

Referring now toFIG. 7, the carrier306is comprised of a gear320disposed on an axial member318. A second gear320is also provided on an opposing end of the axial member318. Since the positioning mechanism300is shown in cutaway view inFIG. 7, only a single one of the gears320is shown. However, it should be understood that the second gear320is substantially the mirror image of the gear320that is shown. When the carrier306is moved along the length of the screw spindle312, the gears320run in two cams322, only one of which is shown inFIG. 7. A first cam is formed in side wall portion325of the mechanism. A second cam (not shown) is provided on opposing side wall portion323of the positioning mechanism300. The second cam is substantially a mirror image of the cam322and performs a corresponding function as hereinafter described. Gear teeth321are disposed along the length of each cam322as shown for engaging each gear320.

As may be observed inFIG. 7, the cams322are not parallel to the base plate334or the to the elongated length of the screw spindle312. Instead, the distance between the y-axis (defined by the screw spindle312) and the cams322increases from the first end324of the frame to the second end of the frame326. Thus, the carrier306is elevated as it moves the combiner106toward the fully extended position. This structure of the cams322causes rotation of the combiner to the erect position shown inFIGS. 6 and 7as the combiner moves toward the fully extended position at the second end of the frame.

Referring again toFIG. 7, a wheel330is provided at a bottom edge portion of the carrier306. A second wheel330can also be provided on an opposing end of the carrier306. Since the positioning mechanism300is shown in cutaway view inFIGS. 3-7, only a single one of the wheels330is shown. However, it should be understood that the second gear320is substantially the mirror image of the wheel330that is shown. The wheels330are mounted on axles348disposed in carrier306which allow the wheels to rotate freely. The wheels are positioned on carrier306so that they move over surface332defined by a base plate334as the carrier is transported by the gears320and cam322. According to an embodiment of the invention, the wheels move over surface332without necessarily touching the surface. However, the invention is not limited in this regard and other arrangements the wheels can roll over at least a portion of surface332.

As the carrier306moves from the first end of the frame324to the opposing second end of the frame326, the wheels approach a ridge336defined on the surface332of the base plate. The ridge is best shown inFIGS. 7 and 9. As the wheels begin to pass over the ridge, they engage its surface. This engagement is illustrated inFIG. 9A. Continued movement of the wheel330along the ridge334urges the a pin344, secured to the side of the carrier306, into a recess338defined in a parking member340.

An enlarged view of the parking member340is shown inFIG. 10. It can be observed inFIGS. 9 and 10that the parking member340is pivotably secured to frame302at pivot point341. Any suitable fastener345can be used for this purpose. For example, the fastener345can be a threaded screw or a rivet secured to the frame340. The fastener can pass through a bore (not shown) formed in the parking member340. The pivoting motion of the parking member340defines a pivot axis343as shown inFIG. 10.

Referring once again toFIGS. 8 and 9, it can be observed that parking member340is resiliently biased at a first end346by a spring342. The spring342is attached at a first end346of the parking member. An opposing end of the spring342is attached to the frame302. The spring342resiliently urges the first end346of the parking member downwardly (in the direction of the base plate334). The pin344is thus resiliently engaged securely in the recess338.

It may be noted that the parking member340is shown to have the form of a lever. However, it should be understood that the invention is not limited in this regard. The parking member340merely needs to be a resiliently biased member having a recess into which the pin338is securely engaged. Accordingly, other structures can be used to define the parking member without limitation.

Referring again toFIG. 9A, the wheel330supports the carrier306against the resilient force applied by parking member340and spring342. The force applied to the carrier306can cause the carrier306to shift downwardly slightly, toward the ridge336. For example, the force applied by the spring342can cause the carrier306to shift downwardly about 0.2 mm. Accordingly, a clearance space is advantageously provided within bore319around the guide rod328to prevent binding of the guide rod within the bearing317. Further, in order to prevent excessive play between the guide rod328and the bearing317a resilient spring member (not shown) can be provided within the bearing317. The resilient spring, which is preferably in contact with the top of the guiding rod328, is compressed against the guiding rod when the carrier306is urged downwardly in response to the engagement with the recess338.

InFIG. 9B, it can be observed that the gear320has reached the end of its travel along the cam322and comes to rest in a stop member350. In this position, the gear320is lifted out of the cam322. This is accomplished by the gear320rotating and engaging the gear teeth formed into the stop member350. With the gear320securely seated in the stop member350, unwanted rotation of the gear320as may potentially be caused by vibration, is prevented.

According to one embodiment of the invention, the stop member350can be seated on a resilient spring member (not shown). However, this feature is not necessary to the invention and the stop member350can also be rigidly mounted. According to another embodiment of the invention, the cam322can be extended to include the position occupied by the stop member350, and the stop member350can be eliminated entirely.

With the carrier securely positioned as shown inFIG. 9B, the pin344forms a rotational axis about which the carrier306and the combiner106can pivot. Notably, pin344permits the carrier306to rotate within the recess338. The permitted rotation permits an angular adjustment of the carrier306(and the attached combiner106) to facilitate proper operation of the combiner.

A second pin344can also be provided on an opposing end of the carrier306. Since the positioning mechanism300is shown in cutaway view inFIGS. 3-9, only a single one of the pins is shown. However, it should be understood that the second pin344is substantially the mirror image of the pin344that is shown. Similarly, a second parking member340, and a second spring342, can also be provided on a side of the carrier306opposed from the first parking member. In other words, to have the whole combiner positioning mechanism properly balanced, the basic mechanism described inFIGS. 8-9is provided symmetrically on each end of the carrier rotation axis defined by pin344.

FIG. 11is a schematic diagram which shows the carrier306in its fully extended and locked position. It can be observed inFIG. 11that the pin344is secured within the recess338by the resilient force of the parking member340and spring342, thereby preventing lateral motion at the top of the carrier. The bottom of the carrier306is firmly supported on the wheel330. Moreover, the lower portion of the carrier is prevented from moving by the force exerted upon it by the bearing317. The bearing317is held immobile by the threaded portion of the screw spindle312, which is not shown inFIG. 11.

In order to provide a rigid support for the combiner when it is fully extended, the carrier306must be clamped with a very high force. Still, in order to permit fine adjustment in the position of the combiner106even when the carrier is clamped, it must be possible to move the carrier306in fine steps with the same low motor torque as used when the carrier is threaded along the y-axis. The inventive arrangements permit both of these design goals to be effectively achieved.

Referring again toFIG. 11, note that the carrier306has a rotation axis about pin344. The rotation axis permits a rotation of the carrier306within the recess338, which in turn facilitates a certain angle of rotation352of the combiner. According to an embodiment of the invention, the motor304is responsive to control signals provided from controller204for rotating screw spindle312in small increments. The small increments of rotation facilitate precise angular adjustment of the combiner106by varying the angle of rotation352.

A relatively large parking force is applied by spring342to the carrier306for securing the combiner in place. The force from spring342is applied from the recess338, through carrier306and its wheels, into the base plate334(parking force). This relatively large force will make the system resistant against shock and vibration. As noted above, the entire carrier system is balanced by providing the mechanism shown inFIGS. 8 and 9symmetrically on each side of the carrier rotation axis.

While the foregoing arrangements represent one possible solution to the vibration problem, it should be understood that the invention is not limited in this regard. For example, instead of the interaction of the spring loaded parking member340and ridge336, the same objective could also be achieved by any other spring force solution. For example, the carrier306could be divided into an upper and a lower part where two parts are spring loaded to push away from each other. Alternatively, it will be appreciated that the wheels330on the carrier306could be resiliently mounted at the base of the carrier so that they can deflect towards the combiner106when riding up on ridge336. Either of these solutions can provide a substantial force between the recess338and the base plate334. Still, the invention is not limited in this regard.

With the arrangement described herein, any minor adjustments in the angular position of the combiner106can be made by application of an adjustment force FAas shown inFIG. 11. Significantly, however, because the adjustment force is applied at an angle of approximately 90° relative to the parking force, the direction of the adjustment force can be much smaller than the parking force FP. Consequently, only a small force FAin an adjustment direction (y-axis) is required to maintain an exact position of the carrier.

Finally, it should be noted that placement of the wheels330on the carrier306running along the base plate334provides an effective solution with regard to the adjustment problem. The parking force FPis entirely supported by the wheels330. Advantageously, however, the wheels330can still roll with reasonable amount of friction under a high spring load applied by spring342. In principle however, the wheels330can also be replaced by any low friction slide solution. For example, the base of the carrier can be provided with a low friction bearing member that engages a corresponding low friction surface supported on the base plate. Still, the invention is not limited in this regard. Any suitable low friction material can be used for this purpose.

When the combiner is to be returned to its retracted position, the direction of the motor304is reversed. The resulting motion of the carrier306is the same as previously described, except that the carrier now moves in the opposite direction, toward the first end324of the frame302. The actions described above inFIGS. 3-7are performed in reverse order.