The invention relates to a device for taking picture of a jaw part with elements such as tooth or molar tooth, said device mainly comprising a holder to be orienta¬ ted with respect- o a source of radiation having a windowed screen to be positioned in front of said source, a carrier arranged at a distance therefrom for retaining a picture pla te at a predetermined angle of, for example, 90° to the beam of rays and a biting element extending in the direction of the beam of rays. Such a device serves to position the picture plate with respect to the beam of rays, which may be an X-ra beam commonly used in dentistry for taking X-ray pictures.

The invention has for its object to improve the device set forth above in a sense such that the picture plate can be positioned more accurately than before with res¬ pect to the beam of rays determined by the window in the screen, whilst nevertheless the device remains friendly to the user, that is to say, this positioning does not give rise to any appreciable problem to the user and to any appreciable nuisance for the patient.

The invention provides a device which is dis¬ tinguished in that a releasable cap-shaped positioning member is arranged on the carrier and the picture plate placed thereon for positioning the picture plate with respect to the window.

The cap-shaped positioning member embodying the invention thus has a double function i.e. determination by its shape of the position of the picture plate with res¬ pect to the screen and, in addition protection of the patient against nuisance. The conventional picture plates have rela¬ tively sharp and/or hard edges, which are now covered by the cap so that these edges will not injure the delicate mucous membrane in the oral cavity. The carrier is preferably

provided with a supporting rim of a stepped shape so that picture plates of different thickness can be effectively held in place.

It is furthermore preferred to construct the supporting rim with a back part of the carrier so as to be displaceable in height with respect to the holder so that the picture plate can be displaced transversely of the beam of rays.

According to a further aspect of the invention the biting element is slidable parallel to the supporting rim with respect to the carrier. This has the advantage that the biting element can be positioned at the side of the jaw part to be displayed, which is particularly effective when wisdom teeth have not yet emerged or when elements are lacking. It is furthermore preferred to provide reces¬ ses in the element for- receiving a curable mass. By keeping the biting element with the impression it is ensured by this step that, when taking a new picture after some time, the holder can be accurately positioned with respect to the oral cavity so that a correct comparison of pictures taken prior to and after the treatment can be made.

The above mentioned and further features of the invention will become apparent from the following des¬ cription of the figures of an embodiment. The drawing shows in:

Pig. 1 a schematic disposition of a device embodying the invention with respect to the oral cavity.

Fig. 2 a perspective view of the device of fig. 1, Fig. 3 a perspective view of the carrier with the picture plate placed thereon on an enlarged scale.

Fig. 4 a perspective view of the top part of the carrier of fig. 3 with a different type of picture plate,

Fig. 5 a perspective view like that of fig. 3 of the carrier without the cap.

Fig. 6 a perspective view of the rear side of the carrier of fig. 5 in the direction of the arrow P1,

Fig. 7 a perspective view like that of fig. 3

of the carrier, the various parts being shown separately.

The device shown in the figures mainly comprises a source of radiation 1, which may be of different nature. It may be an X-ray apparatus. The source of radiation is directed with the aid of a holder 2 carrying a screen 3 having a window for directing and forming a beam of rays from the source 1. At a distance from the screen 3 the holder 2 is provided with a carrier 4 provided with a biting element 5. From fig. 1 it is clearly apparent that the patient's teeth are placed on the biting element 5 in a manner such that the carrier 4 is located in the oral cavity on the rear side of the jaw elements T with respect to the source of radiation 1. The carrier 4 supports a picture plate 6, which is sensitive to the radiation emitted by the source 1 so that a screening image of the jaw with the elements set therein can be made. This technique is known per se and lies beyond the scope of this invention.

Referring to figs. 3 to 7 an embodiment of the carrier according to the invention will be described more fully.

The carrier 4 comprises a first spray-cast part 10 provided with two upright posts 11 having a bore 12 for receiving the end of the holder 2. The connection between the part 10 and the holder 2 can be established by clamping effect. On the front side the posts 11 have a ridge 13 along which a sleeve 14 of the biting element 5 can be slid to and fro in the- direction of the arrow P1. The ridge 13 has no stops so that the sleeve 14 or the biting element 5 can be entirely slid from the ridge 13 and again be slid onto it.

Between the posts 11 is formed a space 15 into which project two ridges 16 connected with each post. These ridges serve for guiding a back part 17 of the carrier 4 which is displaceable in a direction of height. On the rear side the back part (see fig. 6) is provided for this purpose with a hook-like bracket 18 perpendicular thereto, the bent- over end of which grips behind each ridge 16. The ridge 16 is furthermore provided with ribs 19 or the like, between

which will snap the bent-over end part 18 so that the back- part 17 can be positioned in height with respect to the lower part 10. The back part has furthermore two end flanges 20 gripping around the posts 11 so that a sliding movement in a direction of height is allowed.

On the front side the back part 17 is provided with a foot rim 21, which has a stepped top face 22. It is thus possible to acco odate a picture plate B1 formed by a film suitable for X-rays and being relatively thin in the groove 24 nearest the front face 23. Besides it is possible to accomodate a picture plate B2 of fig. 4 formed by a thicker, xerographic plate suitable for X-rays in the ^' broader part of the foot between the end rim 25 and the front side 23 of the back part 17. Finally the back part 17 is associated with a cap-shaped part 26 having a cavity 27 such that it fully covers the back part 17 and the picture plate B1 or B2 res¬ pectively.

By this cavity it is ensured that the picture plate B1 is accurately positioned with respect to the back plate 17 in a lateral and upward sense so that also the pic¬ ture plate is accurately positioned with respect to the screen 3 and the window therein for obtaining the correct picture. The cavity 27 is, of course, adapted to the di en- sions of the desired picture plate.

The cap 26 is fully rounded off on the outer side end and it is preferably made from a relatively soft, elastic X-ray pervious material so that not only a satisfac¬ tory clamping effect on the picture plate B and the back part 17 can be obtained, but also the relatively weak mucous mem¬ brane in the oral cavity will not be injured.

The biting element 5 may have a recess 29 for receiving a curable mass to be arranged in advance. The tooth or molar tooth will leave a impression in this curable mass so that re-arrangement of the biting element 5 in the mouth is facilitated when afterwards again a picture has to be taken to judge variations in the patient.

For accurately positioning the biting element with respect to the carrier 4 the back 13 may have marking lines 30, which can be noted on the picture and the biting element 5. The invention is not limited to the embodimen described above, since within the scope of the invention various modifications are possible.

For example, the connection of the carrier 4 with respect to the holder 2 can be varied in dependence on the plate in the oral cavity for the picture carrier. As a matter or course, guiding and locking of the back part 17 displaceable in height may be designed in any desired manner