ENDOSCOPIC PROBE INTEGRATING A COMPACT OBJECTIVE

Abstract

An endoscopic probe is provided including a distal end (11, 31) having an image sensor (1) with a substantially rectangular light-sensitive surface (2) associated with an objective arranged for transmitting a light beam having a proximal section substantially identical to the light-sensitive surface of the image sensor. The objective includes at least one distal lens (32, 33) produced from a circular lens, wherein parts of the circular lens that are not passed through by light rays transmitted by the objective to the light-sensitive surface (2) have been removed, so as to reduce the lateral dimensions of a distal part of the objective, in order to particularly house a high-power lighting device.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

FIG. 1 is a longitudinal cross-sectional view of the distal end of a videoendoscopic probe comprising a distal terminal end associated with a classic removable head,

FIG. 2 is a front view of the distal end of the distal terminal end represented in FIG. 1,

FIG. 3 is a front view of the distal end of the removable head represented in FIG. 1,

Fig. is a longitudinal cross-sectional view of the distal end of a videoendoscopic probe comprising a distal terminal end associated with a removable head according to the present invention,

FIG. 5 is a front view of the distal end of the removable head represented in FIG. 4,

FIG. 6 is a perspective view of the distal end of the distal terminal end represented in FIG. 1,

FIGS. 7 and 8 are longitudinal cross-sections of a removable head according to the present invention, lockable onto the distal end of a probe represented in FIG. 6,

FIGS. 9 and 10 are perspective views of the removable distal head represented in FIGS. 7 and 8,

FIGS. 11A, 11B, 11C are timing diagrams of control signals applied to the image sensor of the videoendoscopic probe,

FIG. 12 is a schematic wiring diagram of a pulsed power supply circuit of the lighting device.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 to 3 represent the distal end of a classic videoendoscopic probe. In FIGS. 1 to 3, the distal end of the videoendoscopic probe comprises a distal terminal end 11 associated with a removable distal head 15 lockable onto the distal terminal end. In FIGS. 1 and 3, the removable distal head 15 classically comprises a lighting device comprising several low-power light-emitting diodes (LED) 22 (six in the example in FIG. 3) packed in compact SMC boxes spread in a ring around the objective.

In FIGS. 1 and 2, the distal terminal end 11 comprises a tubular cylindrical body 12 having a distal transverse partition 13. The body 12 houses an image sensor 1 comprising a rectangular light-sensitive surface 2 protected by a transparent plate 3, and a circular infrared filter 4 having a diameter at least equal to the diagonal of the light-sensitive surface 2 of the image sensor. The infrared filter 4 is fixed onto the partition 13 in front of a central circular orifice formed in the latter. The distal terminal end 11 of the probe is extended by a cylindrical tube 14 used as a receptacle for a proximal part 17 of the removable head 15.

In FIGS. 1 and 3, the removable head 15 comprises a tubular cylindrical body 16 having an external diameter substantially identical to the distal terminal end 11. The body 16 houses a cylindrical mount 20 of an objective comprising, successively centered along an optical axis OZ, a converging proximal lens 5, a converging median lens 6, an aperture diaphragm 8 installed in an opaque disc 7 and a diverging distal lens 9. All the optical components of the objective have a circular section having a diameter substantially identical to that of the infrared filter 4.

The proximal part 17 of the removable head 15 has a slightly smaller diameter than the interior diameter of the distal tube 14, so as to be capable of being introduced into it until a proximal face 18 of the removable head 15 comes in contact with the distal partition 13 of the distal terminal end 11.

The distal end of the tubular body 16 is extended by a cylindrical tube 19 delimiting a distal volume located between the internal face of the tube 19 and the external face of the cylindrical mount 20 of the objective. This distal volume enables a lighting device to be housed comprising a printed circuit 21 in the form of a ring supporting six LEDs 22 packed in SMC boxes and protected by a distal transparent plate 24 in the shape of a ring. The printed circuit 21 is linked by two electrical conductors 25 to two contact pads 27 housed in insulating bases 26 arranged on the proximal face 18 of the removable head 15. When the removable head 15 is locked onto the distal terminal end 11, the two contact pads 27 of the removable head 15 come into electrical contact with two similar contact pads 28, housed in insulating bases 29 arranged on the distal partition 13 of the distal terminal end 11. The contact pads 28 are linked to an electrical power supply device by two electrical conductors 30.

The “useful” light rays, i.e. contributing to form the video image supplied by the videoendoscopic probe, are spread in an output window Q corresponding to the light-sensitive surface 2 of the image sensor 1. The window Q has a rectangular shape the width/height ratio of which is equal to 4/3. A light ray 10 ending at a point A on the edge of the window Q and contained in a longitudinal plane OXZ including an optical axis OZ of the optical system, successively passes through an input point A3 located on the distal face of the distal lens 9, through a point A2 located on the proximal face of the median lens 6, and through a point A1 located on the proximal face of the proximal lens 5.

The “useful” light rays successively pass through a series of homothetic rectangular windows of the window Q. The width/height ratio of these windows therefore remains equal to 4/3. The output window Q is centered on a point O located at the intersection of the optical axis OZ and of the light-sensitive surface 2 of the image sensor 1. The height of the window Q (width of the window Q along the axis OX) is equal to twice the length of the segment O-A. Before arriving in the window Q, the light rays pass through a window Q1, centered on a point O1 located at the intersection of the optical axis OZ and of the proximal face of the lens 5. The height of the window Q1 is therefore substantially equal to twice the length of the segment O1-A1. Before arriving in the window Q1, the light rays pass through a window Q2, centered on a point O2 located at the intersection of the optical axis OZ and of the proximal face of the lens 6. The height of the window Q2 is therefore substantially equal to twice the length of the segment O2-A2. The light rays enter the removable distal head 15 through an input window Q3 centered on a point O3 located at the intersection of the optical axis OZ and of the distal face of the lens 9. The height of the window Q3 is therefore substantially equal to twice the length of the segment O3-A3.

The principle of the present invention consists in reducing the dimensions of the distal part of the objective by removing non-useful parts of the circular lenses 6, 9, i.e. parts not passed through by the (useful) light rays transmitted to the light-sensitive surface of the sensor 1. The respective sections of the lenses 5, 6 and 9 can thus be reduced substantially to the rectangular windows Q1, Q2, Q3, without affecting the optical characteristics of the objective.

FIGS. 4 and 5 represent a videoendoscopic probe distal end according to one embodiment of the present invention. In FIGS. 4 and 5, the videoendoscopic probe distal end comprises a distal terminal end 11, associated with a removable distal head 31 lockable onto the distal terminal end 11. The distal terminal end 11 represented in FIG. 4 is identical in every respect to the distal terminal end previously described with reference to FIGS. 1 and 2.

The removable distal head 31 represented in FIGS. 4 and 5 differs from the removable head 15 described above with reference to FIGS. 1 and 3, in the following respects.

Only the proximal lens 5 keeps its circular shape, while the lenses 6 and 9 (FIGS. 1 and 2) have been respectively replaced by a median converging lens 32 and a diverging distal lens 33. The lenses 32, 33 each have a rectangular section substantially equal to the largest of the two windows Q2 and Q3. In the case of the optical system represented in FIGS. 1 and 3, the window Q3 is the largest.

Therefore, in the example in FIGS. 3 and 4, the lenses 32 and 33 have a section of dimensions substantially identical to those of the rectangular window Q3 centered on the point 03 located at the intersection of the optical axis OZ and of the distal face of the distal lens 33. As mentioned above, the window Q3 has a height equal to twice the length of the segment O3-A3 and a width/height ratio equal to 4/3.

The lenses 5, 32, 33 are fixed into a tubular objective mount having a circular section proximal part 34 housing the proximal lens 5 and a rectangular section distal part 36 housing the median lens 32 and the distal lens 33. The distal part 36 of the objective mount thus has walls parallel to a first longitudinal plane OXZ and to a second longitudinal plane OYZ perpendicular to the first longitudinal plane.

The distal volume between the internal face of the external tube 19 of the removable head and the walls of the distal part 36 of the objective mount, proves to be sufficiently large to be capable of housing a lighting device comprising two high-power LEDs 38, 39 each associated with a field lens in an SMC box, a printed circuit 37 supporting the two LEDs and distal ports 40, 41 protecting the LEDs. The SMC boxes in which the two diodes 38, 39 are packed have a surface which can reach, with identical probe diameters, 2.5 times that of the SMC boxes in which the six diodes 22 integrated into the removable head 15 are packed.

The present invention thus enables for example one or two LEDs packed in SMC boxes of 2.0×1.6 mm, each supplying a candle power of 9 candelas, to be housed in an axial-viewing removable distal head with a diameter of 6 mm.

In practice, the lenses 32 and 33 are manufactured from circular lenses, such as the lenses 6, 9, having a diameter substantially equal to the diagonal of the widest rectangular section of the part of the useful light beam passing through the two lenses. The lenses 6, 9 are machined by causing each of them to undergo two symmetrical lateral milling operations so as to form two opposite edges that are straight and symmetrical in relation to the center of the lens. These straight edges are spaced by a distance corresponding substantially to the width of the widest section of the useful light beam in the zone of the two lenses 6, 9, i.e. in the example of the Figs. the width of the window Q3. The edges of the lenses between the straight edges can remain circular.

FIGS. 6 to 10 show the principle of assembling and locking the distal head 31 onto the distal terminal end 11.

FIG. 6 represents the distal part of the distal terminal end 11, and in particular the external cylindrical tube 14 and the partition 13. In addition to the elements described with reference to FIGS. 1 and 2, the partition 13 comprises a blind cylindrical orifice 45 located in the longitudinal plane of symmetry OYZ.

In addition to the elements described with reference to FIGS. 1 and 2, the cylindrical tube 14 comprises two diametrically opposite slits in bayonet shape. Each slit comprises a longitudinal part 42 with an open distal end contained in a longitudinal plane of symmetry bisecting the two longitudinal planes of symmetry OXZ and OYZ, and a transverse part 44 comprising a closed end located in the longitudinal plane of symmetry OYZ.

FIGS. 7 and 8 represent the axial-viewing removable head 31 which is lockable onto the distal terminal end 11 represented in FIG. 6. The removable head 31 comprises a central core 16 and an annular locking device 50.

FIG. 7 is a cross-section of the removable head 31 in the longitudinal plane of symmetry OXY, while FIG. 8 is a cross-section of the head according to the longitudinal plane of symmetry OXZ.

The central core 16 of the removable head 31 comprises an axial orifice housing the objective mount as described previously with reference to FIGS. 4 and 5.

In addition to the elements described with reference to FIGS. 4 and 5, the proximal face 18 of the central core 16 comprises a pilot point 48 located in a longitudinal plane of symmetry OYZ.

The central core 16 comprises a distal part 47 comprising a hollow located around the distal part 36 of the objective mount. This hollow houses the lighting device as described previously with reference to FIGS. 4 and 5.

The central core 16 comprises a proximal part 46 arranged for being engaged into the distal tube 14 of the distal terminal end 11. The proximal part 46 has a diameter greater than that of the distal part 47 of the core. The distal part 47 comprises an external radial finger 49 intended to longitudinally guide the annular locking device 50.

The locking device 50 which surrounds the distal part 47 of the central core 16 has a proximal cylindrical part 53 having an external diameter substantially identical to the external diameter of the proximal part 46 of the central core 16, and a distal cylindrical part 56 having an external diameter substantially identical to that of the distal terminal end 11. The proximal part 53 of the locking device 50 comprises two diametrically opposite external radial fingers 51 located in the longitudinal plane of symmetry OYZ. The fingers 51 are arranged to engage into and simultaneously circulate in the two bayonet-shaped slits 42, 44 made in the distal tube 14 of the distal terminal end 11. The distal part 56 of the locking device 50 comprises a closed longitudinal slit 52 in which the radial finger 49 fitted into the distal part 47 of the central core 16 circulates. The distal part 56 also comprises an internal annular housing 54 containing a coil spring 56 pressing on the radial finger 49 so as to exert a longitudinal pressure tending to take the finger back towards the proximal end of the longitudinal slit 52.

FIGS. 9 and 10 show the operation of locking the removable head 31 represented on FIGS. 7 and 8, onto the distal terminal end 11 represented in FIG. 6.

During an insertion phase, the proximal cylindrical part 46 of the central core 16 of the removable head 31 is inserted into the distal end of the tube 14 of the distal terminal end 11 until the two radial fingers 51 fitted into the proximal part 53 of the locking device 50 are engaged in the distal ends of the open longitudinal slits 42 made in the distal tube 14.

During a next compression phase, the proximal part 46 of the central core 16 of the removable head 31 is pushed as far as possible into the distal part of the tube 14 of the distal terminal end 11 by a longitudinal pressure exerted on the distal part 56 of the locking device 50. At the end of the compression phase, the respective positions of the various elements of the distal terminal end 11 and of the removable head 31 are then in the following configuration.

The coil spring 55 housed in the distal part 56 of the annular locking device 50 is compressed to a maximum. The radial finger 49 fitted into the distal part 47 of the central core 16 presses on the distal end of the closed longitudinal slit 52 made in the distal part 56 of the annular locking device 50. The two radial fingers 51 fitted into the proximal part 53 of the annular locking device 50 press on the proximal ends 43 of the longitudinal slits 42 made in the distal tube 14 of the distal terminal end 11. The proximal face of the proximal part 53 of the annular locking device 50 presses on the distal face of the proximal part 46 of the central core 16. The proximal face of the distal part 56 of the annular locking device 50 presses on the distal edge of the distal tube 14. The distal face of the pilot point 48 fitted into the proximal face 18 of the central core 16 presses on the distal face 13 of the transverse partition of the distal terminal end 11.

During a next locking phase, the removable head 31 in the distal terminal end 11 is rotated 45° anticlockwise. At the end of the locking phase, the respective positions of the various elements of the distal terminal end and of the removable head are in the following configuration.

The two radial fingers 51 fitted into the proximal part 53 of the annular locking device 50 press on the ends of the transverse arms 44 of the bayonet-shaped slits 42, 44 made in the distal tube 14. The point 48 fitted into the proximal face 18 of the central core 16 is housed in the blind cylindrical orifice 45 made in the transverse partition 13 of the distal terminal end 11. The proximal face 18 of the central core 16 presses on the transverse partition 13 of the distal terminal end 11. The contact pads 27 fitted into the proximal face 18 of the central core 16 come into contact with the contact pads 28 fitted into the transverse partition 13 of the distal terminal end 11. The coil spring 55 housed in the distal part 56 of the annular locking device 50 is slightly slack compared to the previous compression phase, such that the radial finger 49 fitted into the distal part 47 of the central core 16 is positioned in the median part of the slit 52 made in the distal part 56 of the annular locking device 50.

The locking thus obtained removes any possibility of accidental unlocking. The unlocking of the removable head 31 indeed requires the user to push the finger 49 away, using a sharp tool, towards the distal end of the slit 52 before turning the removable head 31 by 45° clockwise, so as to release the fingers 51 from the bayonet-shaped slits 42, 44 made in the distal end of the tube 14.

FIGS. 11A to 11C represent timing diagrams of control signals applied to the image sensor of the videoendoscopic probe when the sensor is of “interline transfer tricolor” CCD type. FIG. 11A represents line synchronizing pulses 62, and frame synchronizing pulses 60 emitted with a period equal to t1, i.e. 20 ms in PAL standard. FIG. 11B represents integrating pulses 63 of a duration equal to t2 and synchronous with the pulses 60.

The potential troughs of the light-sensitive layer of the image sensor 1 are only loaded during activation periods of duration t2 of the integrating signal 63. Therefore, the efficiency of the lighting device in terms of lighting is not substantially altered if the lighting device supplies, not a continuous light but a pulsed light of the same intensity comprising light pulses synchronous with the pulses 63 and having a duration equal to or greater than the activation duration t2 of the integrating signal.

Therefore, FIG. 11C represents the control pulses 64 for controlling the conduction of the LEDs 38, 39. The pulses 64 have a duration t3 equal to or slightly greater than the duration t2 and are also synchronous with the pulses 60.

With identical current intensities, the diodes 38, 39 powered in pulsed mode supply lighting substantially identical to that supplied in continuous mode, but with a lesser temperature rise. With identical current power and thus temperature rise, the diodes 38, 39 supply lighting in pulsed mode greater than that supplied in continuous mode.

FIG. 12 represents a schematic diagram of the pulsed supply device for powering the LEDs 38, 39. The supply device comprises a current generator 66 supplying a current of constant intensity which powers the diodes 38, 39 hard-wired in series through an electronic switch 67. An input 65 of the generator 66 is linked to a direct voltage source.

The control circuit of the switch 67 comprises a monostable circuit CMC supplying a pulse of duration t3 when a short pulse is applied to an input 69 of the monostable circuit. The short pulse is synchronous with the rising edge 61 of the frame synchronization signal 60.

It will be understood by those skilled in the art that various alternative embodiments and applications of the present invention may be made. In particular, the present application describes an axial-viewing removable head having a compact optical system, a pair of LEDs, and a locking device enabling the head to be associated with the distal terminal end of a videoendoscopic probe equipped with an image sensor of the “interline transfer tricolor” CCD type centered on the mechanical axis of the terminal end. It goes without saying that the present invention can also be applied to an endoscopic probe implementing another image capture technology than the one described above, or in which the optical axis of the image sensor integrated into the distal terminal end is not merged with the mechanical axis of the terminal end, or even to a fixed head endoscopic probe in which the optical system and the lighting device described in the present invention are integrated into the distal terminal end of the probe.

The present invention can also be applied to a deviated viewing removable head comprising a distal reflecting prism added to the optical system described previously, and the two LEDs being offset in the distal end of the removable head 31 so that the axes of the light beams of the LEDs are parallel to the viewing axis of the removable head.

The present invention can also be applied to the removable heads of endoscopic probes integrating an optical image splitting component, such as a delta prism for example, or an auxiliary image projecting device comprising for example a laser diode or an optical collimator intended to transmit the laser beam transmitted by a fiber integrated into the videoendoscopic probe.

In the case of endoscopic probes provided to be associated with a removable distal head, the objective is not necessarily entirely housed in the removable head. For example, the lens 5 of the objective can be housed in the distal terminal end of the probe.

Furthermore, it is not essential to provide two LEDs in the removable head. A single LED is sufficient if the LED supplies a light intensity sufficient for the intended use of the endoscopic probe.

In addition, if the lighting device chosen so permits, it is not necessary to reduce the section of the median lens 6 to house the lighting device. Using a distal lens of reduced section can be sufficient in certain cases. On the other hand, it is important that the proximal lens has a section corresponding to the light-sensitive surface of the image sensor and that the distal lens has a reduced section compared to the section of the proximal lens to house a lighting device supplying sufficient candle power.

It is not essential either for the two lenses 32, 33 having a reduced section compared to the proximal lens 5 to have the same section. If the lighting device used so permits, the median lens can have a larger section than that of the distal lens.

All the lenses of the objective can be machined so as to have a section corresponding to that of the light beam passing through them and covering the entire light-sensitive surface of the image sensor. In practice, the lenses of the objective have two different sections, one section corresponding to the light-sensitive surface for the proximal lens(es) and one section corresponding to the largest section of the distal part of the light beam passing through the distal part of the objective for the distal lenses.

The present invention can also be applied to other types of objectives than the one described above. Therefore, the objective can have more lenses and/or an arrangement of converging and diverging lenses different from the one described above.

The present invention can also be applied to the integration of devices other than a lighting device into the distal end of an endoscopic probe. Thus, reducing the dimensions of the objective can enable for example a laser diode of a metrology device, and possibly a single lighting diode, to be housed.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

Claims

1. An endoscopic probe comprising a distal end comprising an image sensor having a substantially rectangular light-sensitive surface associated with an objective arranged for transmitting a light beam having a proximal section substantially identical to a light-sensitive surface of the image sensor, wherein the objective comprises at least one first distal lens produced from a circular lens, and wherein parts of the circular lens that are not passed through by light rays transmitted by the objective to the light-sensitive surface have been removed, so as to reduce lateral dimensions of a distal part of the objective.

2. The endoscopic probe according to claim 1, wherein the first distal lens of the objective is produced from a circular lens having undergone two symmetrical lateral milling operations, a distance between them being substantially equal to a width of the widest section of a part of the light beam passing through the distal part of the objective and covering the light-sensitive surface.

3. The endoscopic probe according to claim 1, wherein the objective comprises a second distal lens having a section identical to that of the first distal lens.

4. The endoscopic probe according to claim 1, wherein the objective comprises at least one proximal lens of circular section, whose diameter is substantially identical to a diagonal of the light-sensitive surface.

5. The endoscopic probe according to claim 1, wherein the objective comprises at least one proximal lens machined from a circular lens, so as to have a width substantially identical to that of the light-sensitive surface.

6. The endoscopic probe according to claim 1, wherein the objective comprises a first diverging distal lens, a second converging distal lens, and a converging proximal lens, the distal lenses being produced from circular lenses, each having undergone two symmetrical lateral milling operations, a distance between them being substantially equal to a width of a widest section of a distal part of the light beam passing through the objective and covering the light-sensitive surface.

7. The endoscopic probe according to claim 1, comprising a lighting device comprising one or two high-power light-emitting diodes housed at least partly in a volume of the parts removed from the distal lens.

8. The endoscopic probe according to claim 7, wherein the lighting device comprises for each light-emitting diode a field lens, a printed circuit supporting the diode and a distal port protecting the diode.

9. The endoscopic probe according to claim 1, wherein the image sensor is housed in a distal end of the endoscopic probe.

10. The endoscopic probe according to claim 7, wherein at least one distal part of the objective and the lighting device are disposed in a head arranged for being fixed in a removable manner onto a distal terminal end of the endoscopic probe.

11. The endoscopic probe according to claim 10, wherein the removable head comprises a first electrical connection arranged for cooperating with corresponding electrical connection provided in the distal terminal end to ensure electrical connection of the lighting device when the removable head is fixed onto the distal terminal end.

12. The endoscopic probe according to claim 7, comprising a source of power in pulsed current to deactivate the lighting device when the image sensor is not in an acquisition phase.

13. A removable head lockable onto an endoscopic probe distal terminal end, the head comprising at least one distal part of an objective arranged for transmitting a light beam covering a substantially rectangular light-sensitive surface of an image sensor, wherein the objective comprises at least one first distal lens produced from a circular lens, and wherein parts of the circular lens that are not passed through by light rays transmitted by the objective to the light-sensitive surface have been removed, so as to reduce lateral dimensions of the distal part of the objective.

14. The head according to claim 13, wherein the first distal lens of the objective is produced from a circular lens having undergone two symmetrical lateral milling operations, a distance between them being substantially equal to a width of a widest section of a part of the light beam passing through the distal part of the objective and covering the light-sensitive surface.

15. The head according to claim 13, wherein the objective comprises a second distal lens having a section identical to that of the first distal lens.

16. The head according to claim 13, wherein the objective comprises at least one proximal lens of circular section, whose diameter is substantially identical to a diagonal of the light-sensitive surface.

17. The head according to claim 13, wherein the objective comprises at least one proximal lens machined from a circular lens, so as to have a width substantially identical to that of the light-sensitive surface.

18. The head according to claim 13, wherein the objective comprises a first diverging distal lens, a second converging distal lens, and a converging proximal lens, the distal lenses being produced from circular lenses each having undergone two symmetrical lateral milling operations, a distance between them being substantially equal to a width of a widest section of a distal part of the light beam passing through the objective and covering the light-sensitive surface.

19. The head according to claim 13, comprising a lighting device comprising one or two high-power light-emitting diodes housed at least partly in a volume of the parts removed from the distal lens.

20. The head according to claim 19, wherein the lighting device comprises for each light-emitting diode a field lens, a printed circuit supporting the diode and a distal port protecting the diode.

21. The head according to claim 19, comprising a first electrical connection arranged for cooperating with a corresponding electrical connection provided in a distal terminal end of the probe to ensure electrical connection of the lighting device when the removable head is fixed onto the distal terminal end.