Technical Field of the Present Invention

The present invention relates to a light guide device for use in dental imaging applications. More particularly, the present invention relates to a light guide that is attachable and removable from an imaging device (such as a camera) to be used in dental imaging applications.

Background of the Present Invention In the past decades, use of digital photography has become standard for dental practices. The applications for clinical photography in dentistry include: diagnosis and treatment planning, laboratory communication, legal and forensic documentation, as well as patient education and communication (Terry et al., 2008, Compend Contin Educ Dent. 92, pp. 432-6, 438, 440-2, 450, 462). The quality of the dental image is very important, especially with such a wide range of applications. Dental photography comprises extraoral, perioral and intraoral photography and each region has unique considerations that must be kept in mind to acquire the best possible images. The main difficulties that need to be addressed for intraoral photography are the inaccessibility of oral structures, lighting inside the mouth, framing of the image and reproducibility. For example, as the objects to be photographed, such as teeth and mucous membranes of the mouth, are hidden inside the oral cavity, special lighting equipment is needed. Also, as these objects are very small, problems of macrophotography such as magnification ratio, depth of field and perspective distortion need to be taken into account. In addition, due to the high contrast and presence of reflective surfaces inside the oral cavity, exposure concerns emerge. Dental photography needs to balance these concerns in order to successfully provide comprehensive images that reflect the outline, surface texture and color of the object and even some inner structures of the semitransparent teeth (Bengel, 2006, Mastering Digital Dental Photography, 2nd ed., Quintessence, Chicago, IL).

DLSR (digital single-lens reflex) cameras are currently the most commonly used cameras for dental imaging applications. However, the camera body itself is not as critical to high quality dental photography as the lens and lighting selections. Macro lenses (close-up lenses) are the ideal choice in terms of large magnification ratios (e.g. 1 : 1) and focusing at close range. Another parameter is the aperture, which determines the amount of light entering the lens. To obtain the maximum depth of field that is required for dental imaging, the aperture opening must be small, so lenses with large f- stop values (e.g. f-22) are preferable. Point flash, ring flash or twin flash can be used as a light source. While use of ring flash is acceptable, twin flash provides the best images. Twin flash consists of two flashes placed on either side of the lens, with no light coming from the top or bottom. Because the light comes in at a slight angle, there is less specular reflection and some slight shadowing is created which gives depth to the image. The line angle, color effects, subtle color gradations, translucency levels and crack lines can be seen by use of a twin flash (Terry et al., 2001, J Calif Dent Assoc. 29, pp. 735-742). The attempts made in the state of the art to improve dental imaging can be exemplified by the following patent. KR 10-1589737 Bl discloses a device for guiding light from the flash of a camera for use in dental treatment. The device comprises a light leakage prevention frame, to transmit the light from the flash to two light guiding members while preventing light leakage, a support frame so that said light leakage prevention frame can be attached to the flash housing groove. The user can position the light guiding members to desired places to optimally light the oral cavity of a patient. The present invention aims to improve on the prior art. The invention proposes a light guide device that is removably attachable to an imaging device such as a camera for use in dental imaging applications. The invention comprises a light transfer frame, so that the light emitted from the flash can be transmitted to a light guide cable. The invention also comprises a support means to securely attach the light transfer frame to a camera, and a light positioning means to provide adjustable twin flash configuration. Additionally the invention comprises a light directing slide to allow the user further control over the direction of light and optimally highlight the contours and color variations of a patient's teeth. In this manner, the invention aims to provide a practical alternative for use in dental photography applications.

The present invention provides a light guide device for use in dental imaging applications as provided by the characterizing features defined in Claim 1. Objects of the Present Invention

The object of the invention is to provide a light guide device that is removably attachable to an imaging device such as a camera for use in dental imaging applications.

It is a further object of the invention that the light guide device comprise a light transfer frame secured by a support means, whereby the light emitted from the flash of the camera can be transmitted to a light guide cable containing optical fibers.

It is a further object of the invention that the light guide device comprise a light positioning means whereby adjustable twin flash configuration is achieved.

It is a further object of the invention that polarized filters be placed in front of the lens of the camera and the twin light source of the light positioning means in such a manner that their polarizing directions are orthogonal to each other so that cross-polarized lighting is obtained.

Brief Description of the Technical Drawings

Accompanying drawings are given solely for the purpose of exemplifying a light guide device, whose advantages over prior art were outlined above and will be explained in brief hereinafter.

The drawings are not meant to delimit the scope of protection as identified in the Claims, nor should they be referred to alone in an effort to interpret the scope identified in said Claims without recourse to the technical disclosure in the description of the present invention. The drawings are only exemplary in the sense that they do not necessarily reflect the actual dimensions and relative proportions of the respective components of the system. Figure 1 demonstrates a side view of an embodiment of the present invention which is installed on a camera. Figure 2 demonstrates a front view of an embodiment of the present invention which is installed on a camera as depicted in Figure 1.

Figure 3 demonstrates a top view of a light positioning means of the present invention as depicted in Figure 1.

Figure 4 demonstrates a sectional view of a light guide cable of an embodiment of the present invention as depicted in Figure 1.

Figure 5 demonstrates a top view of a light positioning unit of an embodiment of the present invention as depicted in Figure 1.

Figure 6 demonstrates a front view of a light directing slide of an embodiment of the present invention. Figure 7A demonstrates a top view of a light positioning base of an embodiment of the present invention.

Figure 7B demonstrates a bottom view of a light positioning base of an embodiment of the present invention.

Figure 7C demonstrates a top view of a support base of an embodiment of the present invention. Figure 7D demonstrates a bottom view of a support base of an embodiment of the present invention.

Figure 8 demonstrates a front view of a polarizing filter cover of an embodiment of the present invention.

Figure 9A demonstrates a top view of an alternative embodiment of light positioning means of the present invention in closed position. Figure 9B demonstrates a top view of an alternative embodiment of light positioning means of the present invention in open position.

Figure 10 demonstrates a side view of an alternative embodiment of the present invention which is installed on a camera.

Detailed Description of the Present Invention

The following numerals are referred to in the detailed description of the present invention:

10 Camera

11 Lens

12 Flash

100 Light guide device

111 Light transfer frame

112 Light guide cable

113 Twin light guide cable

114 Central light guide cable 120 Support means

121 Support base

122 Support adjustment unit

123 Mounting groove

131 Optical fiber

132 Extendable optical fiber

133 Central optical fiber

140 Light positioning means

141 Light positioning unit

142 Light positioning base

143 Light positioning adjustment unit

144 Light positioning adjustment handle

145 Twin light source

146 Central light source

147 Mounting tab

148 Moving part

151 Light directing slide

152 Light directing window

153 Light directing slide slot

154 Light directing slide adjustment groove

160 Polarizing filter cover

161 Lens polarizing filter

162 Flash polarizing filter

163 Magnet

171 Screw hole

200 Twin light focus point

201 Central light focus point Figures 1 and 2 illustrate an embodiment of the present invention, referred to as light guide device (100). Light guide device (100) comprises light transfer frame (111), light guide cable (112), light directing slide (151), support means (120) and light positioning means (140). Light guide device (100) is attachable to a camera (10) with a lens (11) and a flash (12). Light transfer frame (111) is positioned to be aligned with and fitted tightly against flash (12) so that light emitted from said flash (12) is fully captured. In addition, light directing slide slot (153) is placed at the flash (12) facing end of light transfer frame (111) whereby light directing slide (151) can be inserted and the direction of light can be controlled by changing the alignment of light directing window (152) (see Figure 6).

Light transfer frame (111) is secured in position by support means (120). Support means (120) comprises support base (121) and support adjustment unit (122). Support base (121) is removably attachable to the bottom surface of camera (10) to provide stability. Support adjustment unit (122) may comprise interlocking rods, or other size adjustment mechanisms such as telescopic poles etc. to adjust the height and width of support means (120) to ensure that light transfer frame (111) is aligned with and fitted tightly against flash (12). In other words, the length of said support adjustment unit (122) is adjustable along vertical as well as horizontal axes.

Light emitted from flash (12) is transmitted to light positioning means (140) via optical fibers (131) encased in light guide cable (112). Light guide cable (112) is positioned to be aligned with flash (12) by light transfer frame (111).

Light positioning means (140) comprises light positioning unit (141), light positioning base (142), light positioning adjustment unit (143) and light positioning adjustment handle (144). Light positioning means (140) is attached to the bottom of support base (121) via light positioning base (142), mechanically or by welding. Light positioning base (142) is connected to light positioning unit (141) by light positioning adjustment unit (143). The distance of light positioning unit (141) to lens (11) can be modified by light positioning adjustment unit (143) using light positioning adjustment handle (144). Additionally, light positioning unit (141) comprises twin light sources (145) and central light sources (146). Light guide cable (112) comprises twin light guide cables (113) and central light guide cables (114). Twin light guide cables (113) and central light guide cables (114) transmit light to twin light sources (145) and central light sources (146) on light positioning unit (141) respectively. While Figure 1 laterally demonstrates one of the twin light guide cables (113), both of them are seen in Figure 2. The central light guide cables (114) are not shown in Figure 2 as they are shown at the position where they are inserted into the light positioning unit (141).

The structure of light positioning unit (141) is such that a twin flash system is formed by twin light sources (145) and central light sources (146) provide additional lighting when desired. Twin flash system is ideal for dental imaging as it allows the contours and line angles of teeth to become more pronounced. It is also important that twin light sources (145) and central light sources (146) are placed below the camera and particularly below the central axis of the lens (11) to optimally capture the line angles.

Figure 3 illustrates light positioning means (140) in greater detail. As mentioned above, light positioning base (142) is connected to light positioning unit (141) by light positioning adjustment unit (143). Light positioning adjustment unit (143) has a collapsible scissor structure so that the distance of light positioning unit (141) from lens (11) can be changed by moving light positioning adjustment handle (144) towards or away from camera (10). Light positioning base (142) also comprises screw hole (171) so that light positioning means (140) can be secured to tripod mount hole of camera (11) by a screw. In an alternative embodiment of the invention, additional stands (not pictured) of the same height as light positioning adjustment handle (144) can be placed under moving parts (148) and/or light positioning base (142) whereby light guide device (100) attached to camera (10) can be balanced on a flat surface, such as a table.

Figure 4 illustrates light guide cable (112) in greater detail. In one embodiment of the invention, light guide cable (112) contains 22 optical fibers (131, 132 and 133). Preferably optical fibers (131, 132 and 133) are 3 mm in diameter. Optical fibers (131, 132 and 133) are divided evenly to twin light guide cables (113) and central light guide cables (144) so that each twin light guide cable (113) contains 10 optical fibers (131) and each central light guide cable (114) contains 1 central optical fiber (133) respectively. Optical fibers (131, 132, and 133) transfer light emitted from flash (12) to light positioning unit (141) of light guide device (100). In one embodiment of the invention, at least one extendable optical fiber (132) contained in a twin light source (145) can be unhoused and pulled forward so that the oral cavity of a patient can be better illuminated and more detailed information can be gained on color variations and chipped or broken teeth.

Figure 5 illustrates the angling of optical fibers (131, 132 and 133) in twin light sources (145) and central light sources (146) respectively. 20 optical fibers (131 and 132) divided evenly among twin light sources (145) are positioned such that light emitted from twin light sources (145) is focused at twin light focus point (200) which is centered with respect to lens (11) and light positioning unit (141). 2 optical fibers (133) divided evenly among central light sources (146) are positioned such that light emitted from central light sources (146) are directed at central light focus points (201) which lie above and on two sides of twin light focus point (200).

Figure 6 illustrates light directing slide (151) in greater detail. Light directing slide (151) comprises light directing windows (152) and light directing slide adjustment grooves (154). The desired light directing window (152) may be positioned to be aligned with and fitted tightly against flash (12) by light directing slide adjustment grooves (154). Each window determines whether an optical fiber (131, 132 or 133) will receive transmitted light from flash (12). In an exemplary embodiment of the invention light directing slide (151) contains 3 light directing windows (152) that direct the light to extendable optical fibers (132), to optical fibers (131 and 132) going to twin light source (145) only and to all optical fibers (131, 132 and 133). Figures 7A, 7B, 7C and 7D illustrate light positioning base (142) and support base (121) in greater detail. As can be seen, both light positioning base (142) and support base (121) comprise screw hole (171) so that light positioning means (140) and support means (120) can be secured to tripod mount hole of camera (11) by a screw. Figure 7A illustrates top face of light positioning base (142) which comprises mounting tab (147) and Figure 7D illustrates bottom face of support base (121) which comprises mounting groove (123) corresponding to said mounting tab (147) whereby light positioning base (142) can be securely attached to support base (121). Some models of support base (121) may also comprise protrusions (P) placed in suitable locations corresponding to grooves on the bottom face of a camera model to facilitate attachment of support base (121) to said camera. Figure 8 illustrates an embodiment of the invention where polarizing filters (161 and 162) are attached to lens (11) and twin light sources (145). Polarizing filters (161 and 162) are attached to lens (11) and twin light sources (145) respectively by polarizing filter cover (160). Polarizing filter cover (160) is shaped such that polarizing filters (161 and 162) can be conveniently snapped into their respective places on lens (11) and twin light sources (145) optionally also using magnets (163). Central light sources (146) are blocked by polarizing filter cover (160) and are therefore not operational while using polarizing filters. Polarization directions of lens polarizing filter (161) and flash polarizing filters (162) are orthogonal to each other. Preferably lens polarizing filter (161) is at 90° and flash polarizing filters (162) are at 180°. This arrangement produces cross-polarized lighting. Cross- polarized lighting enhances contrast and eliminates specular reflections which allow the contours and color variations of teeth to become more pronounced, resulting in a higher quality dental image.

Figures 9A and 9B illustrate an alternative embodiment of light positioning means (1400. Light positioning means (1400 comprises light positioning adjustment unit (1430 which has a telescopic pole structure so that the distance of light positioning unit (141) from lens (11) can be adjusted as needed. In the closed position (Figure 9A) light positioning adjustment unit (1430 preferably has a length of 20 cm. In the open position (Figure 9B) light positioning adjustment unit (1430 preferably has a length of 50 cm. Figure 10 illustrates an alternative embodiment of light guide device (1000- Light guide device (1000 comprises light positioning means (1400 attached to camera (10) by light positioning unit (142). The distance of light positioning unit (141) from lens (11) can be adjusted by moving light positioning adjustment handle (144) towards or away from camera (10).

In a nutshell, the present invention proposes a light guide device (100) comprising light transfer frame (111), light guide cable (112) and light positioning unit (141) constructed to be removably attachable to an imaging device with a lens (11) and a flash (12).

In one embodiment of the present invention, said light transfer frame (111) and said light guide cable (112) are in optical communication with flash (12) of said imaging device.

In a further embodiment of the present invention, the transfer of light emitted from the flash of an imaging device to light positioning unit (141) is effectuated by optical fibers (131, 132 and 133) encased in light guide cable (112).

In a further embodiment of the present invention, said light guide cable (112) is positioned to be aligned with said flash (12) by said light transfer frame (111). In a further embodiment of the present invention, said light positioning unit (141) comprises twin light source (145) and central light source (146).

In a further embodiment of the present invention, said light transfer frame (111) is positioned to be aligned with and fitted tightly against said flash (12).

In a further embodiment of the present invention, said light transfer frame (111) comprises light directing slide slot (153) at the flash (12) facing end of said light transfer frame (111) whereby light directing slide (151) is insertable.

In a further embodiment of the present invention, said light transfer frame (111) is secured in position by support means (120).

In a further embodiment of the present invention, said support means (120) comprises support base (121) and support adjustment unit (122).

In a further embodiment of the present invention, said support base (121) is removably attachable to the bottom surface of said imaging device.

In a further embodiment of the present invention, the length of said support adjustment unit (122) is adjustable along vertical as well as horizontal axes. In a further embodiment of the present invention, said support adjustment unit (122) comprises interlocking rods.

In a further embodiment of the present invention, said support adjustment unit (122) comprises telescopic poles.

In a further embodiment of the present invention, said light positioning unit (141) is connected to light positioning base (142) whereby said light positioning unit (141) is removably attachable to said support base (121). In a further embodiment of the present invention, the connection between light positioning unit (141) and light positioning base (142) is facilitated by light positioning adjustment unit (143).

In a further embodiment of the present invention, the distance of said light positioning unit (141) to said lens (11) can be modified by said light positioning adjustment unit (143). In a further embodiment of the present invention, said light positioning adjustment unit (143) has a collapsible scissor structure.

In a further embodiment of the present invention, said light guide cable (112) comprises twin light guide cables (113) and central light guide cables (114).

In a further embodiment of the present invention, the transmittance of light from said light guide cable (112) to said twin light sources (145) is facilitated by twin light guide cables (113) and the transmittance of light from said light guide cable (112) to said central light sources (146) is facilitated by central light guide cables (114).

In a further embodiment of the present invention, said twin light sources (145) and said central light sources (146) are placed below said imaging device.

In a further embodiment of the present invention, said twin light sources (145) and said central light sources (146) are placed below the central axis of said lens (11). In a further embodiment of the present invention, said light guide cable (112) contains 22 optical fibers (131, 132 and 133). In a further embodiment of the present invention, said optical fibers (131, 132 and 133) are 3 mm in diameter.

In a further embodiment of the present invention, said optical fibers (131, 132 and 133) are divided among said twin light guide cables (113) and central light guide cables (144) in such a manner that each said twin light guide cable (113) contains 10 optical fibers (131 and 132) and each said central light guide cable (114) contains 1 central optical fiber (133) respectively. In a further embodiment of the present invention, at least extendable optical fiber (132) contained in a twin light source (145) can be unhoused and pulled out of said twin light source (145).

In a further embodiment of the present invention, said optical fibers (131 and 132) contained in twin light sources (145) are positioned in such a manner that the light emitted from said twin light sources (145) is focused at twin light focus point (200) which is centered with respect to said lens (11) and said light positioning unit (141). In a further embodiment of the present invention, said optical fibers (133) contained in central light sources (146) are positioned in such a manner that the light emitted from said central light sources (146) is directed at central light focus points (201) which lie above and on two sides of twin light focus point (200).

In a further embodiment of the present invention, said light directing slide

(151) comprises light directing windows (152) and light directing slide adjustment grooves (154).

In a further embodiment of the present invention, said light directing window

(152) may be positioned to be aligned with and fitted tightly against said flash (12) by light directing slide adjustment grooves (154).

In a further embodiment of the present invention, the transmittance of light from said flash (12) to said optical fibers (131, 132 and 133) is controlled by the alignment of said light directing window (152) with respect to said flash (12).

In a further embodiment of the present invention, said light directing slide (151) comprises 3 light directing windows (152) whereby light from said flash (12) is transmitted to extendable optical fibers (132), to optical fibers (131 and 132) going to twin light source (145) only and to all optical fibers (131, 132 and 133).

In a further embodiment of the present invention, said light positioning base (142) and said support base (121) comprise screw holes (171) whereby said light positioning means (140) and said support means (120) can be secured to tripod mount hole of an imaging device by a screw.

In a further embodiment of the present invention, said support base (121) comprises mounting groove (123) on bottom face of said support base (121) and said light positioning base (142) comprises mounting tab (147) on top face of said light positioning base (142) configured to fit into said mounting groove (123) whereby said light positioning base (142) is attached to said support base (121).

In a further embodiment of the present invention, said support base (121) comprises protrusions (P) on top face of said support base (121) configured to fit into characteristic grooves of a bottom surface of an imaging device whereby said support base (121) is attached to said imaging device.

In a further embodiment of the present invention, polarizing filters (161 and 162) are attached to said lens (11) and said twin light sources (145).

In a further embodiment of the present invention, said polarizing filters (161 and 162) are fastenable to said lens (11) and said twin light sources (145) by polarizing filter cover (160).

In a further embodiment of the present invention, said polarizing filter cover

(160) is attachable to said lens (11) and said twin light sources (145) by magnets (163).

In a further embodiment of the present invention, polarization directions of lens polarizing filter (161) and flash polarizing filters (162) are orthogonal to each other.

In a further embodiment of the present invention, said lens polarizing filter

(161) is at 90° and said flash polarizing filters (162) are at 180°. In a further embodiment of the present invention, said light positioning adjustment unit (1430 has a telescopic pole structure.

In a further embodiment of the present invention, said imaging device is a camera (10).