Video Display System for Projecting an Image on to a Tilted Screen Adjacent a Surgical Field

The present invention relates to video display systems for displaying a surgical field, and more particularly, to a method and apparatus for projecting an endoscopic image along an optical path and upon a sterilizable screen adjacent the surgical field, wherein the screen is nonperpendicular to the optical path so as to optimize the viewing angle of the projected image and present the image for manual identification by members of a surgical team.

Surgical procedures are often performed in surgical fields which are of a limited size or beneath the skin. With respect to endoscopic procedures, there are several methods for viewing the body interior. For example, the surgeon may look directly through the eyepiece of the endoscope. Alternatively, a beam splitter may be used to provide a second eyepiece for a surgical assistant to simultaneously view the surgical field. For those instances where more than two simultaneous views are necessary, the second view is replaced with a video camera. Splitting the beam between the eyepiece and video camera allows the surgeon to view the surgical field in a high resolution display while the video camera and monitor allow the remaining members of the surgical team to view the procedure. Alternatively, a video camera is mounted directly to the endoscope and one or more monitors are located about the operating environment so that the surgical team may view the field.

Alternatively, liquid crystal display (LCD) monitors can be employed. However, the LCD monitors have a limited viewing angle and an LCD having a sufficient size to permit sufficiently high resolution creates a substantial intrusion to the operating environment. In addition, the LCD monitors are nondisposable, thereby creating a sterilization problem. Further, the accompanying electronics and wires add undesired clutter to the operating environment.

Standard video projection systems are also used. However, the video projecting systems require the screen to be perpendicular to the projection axis. Therefore, locating the display screen at an optimum viewing angle causes a portion of the projected image to be out of focus. Alternatively, the projection path excessively interferes with the operating environment and is subject to frequent interruptions. Further, standard projection screens are irreparably stained by blood and bodily fluids, while disposable flexible screens require stretching or sufficient tension to retain the screens in a proper orientation.

The disadvantages of the prior systems include disorientation created by locating the monitor or projected image of the surgical field remotely from the surgical field. This disorientation is enhanced by the surgeon being unable to view the area of the surgical field and their hands simultaneously. In addition, forcing the surgeon to focus on an image at a relatively large distance while the surgeon's hands are adjacent the body is an unnatural perspective detrimental to the efficiency of surgeons. In addition, constraints on the available locations of the video monitors relative to the surgical field are such that the direction of movement of an instrument within the surgical field is often not translated into a movement in the same direction in the projected image.

Therefore, a need exists for a video display system for an operating environment, wherein a high resolution projected image of a surgical field or other video information may be located adjacent the surgical field and in a viewing orientation which is optimal to the surgeon. In addition, the need exists for a video display system which presents an image which is consistent with the direction of movement within the surgical field. The need also exists for a disposable and/or sterilizable screen for permitting contact with the surgical team or blood and other bodily fluids during the surgical procedure. The need also exists for a viewing screen which may be located at a favorable viewing angle without jeopardizing the integrity of the projected image.

The present invention includes a video projection system designed for a sterile operating environment for locating a viewing screen at an optimum viewing angle adjacent a surgical field and within the reach of the viewers. As the screen is adjacent the surgical field and within reach of the surgical field, direct eye and hand coordination is enhanced as viewers can simultaneously view the display of the surgical field and their hands. In addition, communication is facilitated by permitting manual referencing to the images on the view screen to unequivocally identify areas within the surgical field. Locating the projected image adjacent the surgical field also reduces fatigue of the surgeons.

In a preferred embodiment of the invention an endoscopic surgical field is displayed upon a viewing screen adjacent the surgical field. A high resolution small screen projection system having a tilted projection optic (compensator) projects the endoscopic image along an optical path. Mirrors locate the optical path adjacent the surgical field. A disposable/sterilizable viewing screen is retained along the optical path adjacent the surgical field at a predetermined distance from the projector at a nonperpendicular angle to the optical path. The tilted projection optic and angle between the optical path and the normal to the screen provides uniform focus of the entire projected image upon the screen.

FIG. 1 is a side elevational view of a first embodiment of the present invention;

FIG. 2 is a broken perspective view of the viewing screen;

FIGS. 3a and 3b are side elevational views of the first embodiment of attaching the viewing screen to a rod;

FIGS. 4a and 4b are side elevational views of an alternative attachment of the viewing screen to the mount; and

FIG. 5 is a side elevational view of a second embodiment of the invention.

Referring to FIG. 1, a first embodiment of the present invention is disclosed. A video projector 20 is supported by a stand 40 to be remotely located from an operating table 6 and surgical field 16. The video projector 20 projects an image along an optical path 12, wherein the optical path passes through a tilted projection optic 60 (compensator) and intersects a disposable/sterilizable screen 90. An image gathering system 8, such as an endoscope, as well known in the art is used to gather the image to be projected by the projector 20. The image gathering system 8 is operably connected to the projector 20 via an image gathering system electronic converter 4, as known in the art by a standard transmission line 10, such as a video cable.

The video projector 20 is a self-contained system which projects a high quality high resolution video image along the optical path 12. Preferably, the projector 20 has a resolution which is substantially equal to a surgical video monitor. The projected resolution is approximately 450.times.245 pixels (horizontal by vertical). The video projector 20 may be any of a commercial available types such as the LC300 manufactured by Eiki.

In this embodiment the tilted projection optic 60 (compensator) includes the standard focusing, zoom optics 22 of the video projector 20 and a diopter lens 24. The diopter lens 24 is any of a variety well known in the art, such as the Professional Ser. 9 Plus 1/2 lens manufactured by Tiffen. The diopter lens 24 is used to change the focusing range of the focusing, zoom optics 22 of the projector 20 to the nearer distances. The focusing, zoom optics 22 are adjusted to produce an image the size of the viewing screen 90 at a practical projection length. The focusing, zoom optics 22 are also adjusted to focus the image onto the viewing screen 90. The projection length along the optical path 12 is sufficiently long to position the projector 20 well above or removed from the operating table 6 and out of the way of personnel and equipment. Preferably, the projection optic 60 and projector 20 location are selected to provide an optima image size at the point the optical path 12 is adjacent the surgical field 16. For example in general surgery, these selections would provide a projected image that is approximately life size.

The video projector 20 may be mounted horizontally or vertically. As shown in FIG. 1, in the horizontal mount of the projector, the stand 40 is used to support the projector 20. The stand 40 includes a base 42 having a connected post support 44. A post 46 extends from the post support 44 to terminate a distance above the operating ruble 6. An articulated arm 48 is connected to the post 46 to horizontally locate the video projector 20. Preferably, the video projector 20 is mounted to a base plate 50 which in turn is mounted to the articulated ann 48. Power and video cables 10 may extend within the post 46 and articulated arm 48 to the projector 20.

Alternatively as shown in FIG. 5, the vertical mounting of the projector 20 includes a linear track 52 affixed to the ceiling, wherein the track retains an arm mount 54. A counter balanced ann 56 extends from the arm mount 54 to horizontally displace the projector 20. A projector support 58 is connected to the ann mount 54 to operably retain the video projector 20 in a vertically projecting orientation.

Projection Optic

As shown in FIG. 1, the optical path 12 passes through an object plane 62 and the projection optic 60 and extends to the viewing screen 90. As previously stated, the optimal orientation of the viewing screen 90 and location of the video projector 20 results in the viewing screen being nonperpendicular to the optical path 12. That is, the normal of the screen 90 is set at an angle with respect to the optical path 12. In order to obtain a focused image across the entire angled screen 90, the projection optic 60 makes the object plane 62 conjugate to the screen surface 90. In conventional projection systems, the conjugate object and image planes are nominally perpendicular to the optical axis of the projection optic. In contrast in this embodiment, these planes are tilted relative to the optical axis of the projection optic 60, so that upon projection on the off angle screen 90, the entire image is in focus.

To minimize interference in the operating room and reduce interruption of the projected image, the optical path 12 adjacent the surgical field 16 is substantially vertical and does not include a substantial horizontal component which would interfere with a larger portion of the operating field. Therefore, the foot print of the optical path 12 is substantially minimized.

As shown in FIG. 1, a mirror 70 directs the optical path 12 from the projection optic 60 downward to viewing screen 90. Although only one mirror 70 is shown, a series of mirrors may be used to locate the optical path 12 relative to the surgical field 16.

Referring to FIG. 1, a screen rod 80 depends from the projector base plate 50 and terminates adjacent the operating table 6 and surgical field 16. The screen 90 is affixed to the rod 80 to be located at a predetermined distance from the projector 20. As the rod 80 is mounted upon the articulated arm 48, horizontal location of the screen 90 may be adjusted. The rod 80 is rigidly affixed relative to the projector 20 by threaded fasteners, as well known in the art.

Viewing Screen

The viewing screen 90 is a lightweight compact screen made from a PVC sheet material. Preferably, the optical surface of the screen 90 has a matte white finish. The PVC screen material is not distorted or permanently stained by blood or other body fluids. That is, the screen 90 may be easily rinsed with sterile saline or water and dried with sterile gauze to quickly remove any foreign matter which distorts the projected image.

The viewing screen material has a minimal internal light transmission and scattering. The screen material is rigid and light weight so that only a thin sheet is required to maintain a self supporting planar surface. The viewing screen has the same dimension as a typical video monitor, approximately a 13 inch diagonal. The normal to screen 90 is preferably mounted at an approximately 30.degree. angle from a vertical position, as shown in FIG. 2. Therefore, the vertical size of the screen 90 is longer than the standard 4 to 3 video aspect ratio. However, as dictated by the operating environment, the screen 90 may be from approximately 15.degree. to 85.degree. from a vertical position. As the optical path 12 is substantially vertical in the area of the surgical field 16, the orientation of the viewing screen 90 in a nonhorizontal position provides that the viewing screen is nonperpendicular to the optical path.

Screen Mounting System

The screen mounting system includes the screen mount 82 connected to the rod 80 and a fixture or cooperating structure on the back of the screen 90.

The rod 80 is substantially rigid to eliminate vibration of the screen 90 relative to the video projector 20. In addition, there is at least some adjustability between the video projector 20 and the rod 80 to correct for minor misalignments. The adjustment includes both vertical and horizontal components. However, the horizontal range of motion is relatively small compared to the range of motion of the post 46 and articulated arm 48.

In the first embodiment, as shown in FIGS. 3a and 3b, the screen mount 82 includes a magnetic socket mechanism 84. A plastic encapsulated rectangular magnet 86 is mounted onto the rod 80 and is inclined to the optimal viewing position. The viewing screen 90 includes a socket 92 having a corresponding periphery, wherein the socket includes an embedded layer of steel or other magnetically active material 94. The rectangular shape of the encapsulated magnet 86 matches the shape of the socket 92 so that the screen 90 is easily and accurately placed in the optimal viewing position. The attraction between the magnet 86 and the steel is sufficient to retain the screen 90 in operable position. However, the magnetic attraction is sufficiently small so that if the patient inadvertently contacts the screen 90, the screen with readily disengage to prevent injury. Alternatively, the screen 90 may include spring biased members or a pocket, recess or flange which cooperatively mates with a corresponding structure on the screen mount 82 to releasably and operatively retain the screen relative to the rod 80. In the second preferred embodiment of the screen mount shown in FIGS. 4a and 4b, the screen 90 includes an aperture and depending stabilizing flanges 89 which mate with a screen mount stop on the rod 80.

Operation

Although the present invention is described in terms of endoscopic and laparoscopic surgery, the invention is applicable to any procedure where it is useful to display information adjacent the viewer and the surgical field. The information can be displayed in a video format and include x-rays, ultrasonic or topographic images and vital signs information. As employed for endoscopic surgery, the location, height and orientation of the viewing screen 90 are preferably set for the surgical team prior to surgery. The articulating arm 48 or adjusting track 52 and counterbalanced ann 56 permit locating the viewing screen 90 horizontally and adjusting the vertical control in arm 48 or arm 56 permits the desired orientation of the viewing screen 90. Preferably, the viewing screen 90 is oriented so that the direction of motion in the projected image on the screen directly corresponds to the direction of motion in the surgical field 16. In addition, the viewing screen 90 is located within arms length (approximately three feet) of the surgical field 16 and below eye level of the viewer. While the viewing screen 90 is optimally located adjacent to and at the same vertical elevation as the surgical field 16, the viewing screen may be intermediate the surgical field and eye level of the viewer. In addition, the viewing screen 90 is sufficiently near the surgical field so that a surgeon working in the surgical field which is projected upon the viewing screen 90 can readily contact the viewing screen to identify a portion of the surgical field.

An active video signal and standard AC electrical power inputs are connected to the video projector 20 from the gathering system 8 and converter 4. The active video signal may come from the endoscope or an other image generating mechanism trained on a portion of the surgical field 16. The video projector 20 transfers the electrical video signal into an optical image and projects the optical image along the optical path 12 to the projection optic 60. The image size and focus are set by the details of the projection optic 60 so that they match the viewing screen size and location. Any observed keystoning, a trapezoidal shaping of the image caused by the tilt of the viewing screen relative to the optical path, is corrected at installation by an electronic adjustment of the video projector 20. Alternatively, keystoning can be corrected in the projection optic 60 by including anti-keystoning optical design principles well known in the art.

While a preferred embodiment of the invention has been shown and described with particularity, it will be appreciated that various changes and modifications may suggest themselves to one having ordinary skill in the art upon being apprised of the present invention. It is intended to encompass all such changes and modifications as fall within the scope and spirit of the appended claims.