GB2181584A - Optical reading sensors - Google Patents

Abstract

An optical reading sensor has a lens (26) for receiving a beam of light reflected from a medium carrying optical information. The lens (26) is resiliently supported by an open-ended support (19) which is longitudinally slit near its open end to form a plurality of resilient members (27b) for snugly accommodating the lens therein. The lens directs light to a photo-electric sensor either directly or via an optical fibre (24). <IMAGE>

Description

SPECIFICATION Optical reading sensors The present invention relates to optical reading sensors. Optical reading sensors are used for detecting an information signal from an optical information medium.

Avariety of optical reading sensors made receptive of a reflected beam through a lens from a medium, in which information is optically recorded, to detect an information signal have been proposed in the prior art and put into practice.

In the aforementioned optical reading sensor, incidentally, there have been used a variety of lenses, of which an objective lens is significantly important for inputting oroutputting an optical beam.Thisobject- ive lens is so carefully mounted in a supportthatits optical axis may not be misaligned from a sensor member.

Here, in an ordinary method of supporting the objective lens according to the prior art, an adhesive is applied between the objective lens and the support and is set to fix the objective lens relative to the support. This method, however, is accompanied by a de fect that the alig nment of the optical axis cannot be ensured precisely and easily. According to another method, the objective lens is cut to flatten a portion at its side and is fixed, while its flattened portion being brought into abutment against a flat portion ofthe support, to ensure the positional precision between the support and the objective lens. This method, however, is accompanied by a defect that the aforementioned flattened portion of the objective lens causes secondary reflection of the optical beam to blurthe detected image.

It is an object of the present invention to provide an improved optical reading sensor. The sensors to be described enable a lens to be easily supported with a simple structure.

According to the present invention there is provided an optical reading sensor made receptive of a reflected beam through a lens from a medium, in which information is recorded in an optical state, to detect an information signal, characterised in that said lens is elastically supported by a support.

According to an aspect of the present invention, there is provided an optical reading sensor for receiving an optical beam, which is reflected by a medium recorded with information in an optical state, to detect an information signal, comprising: a light emitting elementforemitting an optical beam to said medium; a lens arranged for receiving and focusing the first-named optical beam reflected by said medium; a light receiving elementforreceivingthe first named optical beam focused by said lens; and an open-ended supportfor elastically supporting said lens near its open end in alignment with said light receiving element so that said lens may guide its focused optical beam into said light receiving element.

An optical reading sensor embodying the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1fa) is an exploded perspective view show ing the whole structure of a firstembodiment; Figure 1fbJ is an exploded perspective view showing the sensor body of the first embodiment; Figure2 is an enlarged sectional view showing the lens supporting portion of the first embodiment; Figure 3 is a sectional view showing the second embodiment; Figure 4 is a perspective view showing the support ofthesecond embodiment; Figure 5is a sectional view showing the third emb- odiment; and Figure 6 is a front elevation showing the third emb- odiment.

Figures 1(a), (b) and Figure 2 show an optical reading device in the form of a bar code scanner.

As shown in Figure 1(a), a sensor body 1 is electrically connected to a printed circuit board 11 carrying an electric processing circuit 10. The printed circuit board 11 is electrically connected through a cable 13 to a connecter 12 which makes contact at its end with the connecting portion of the not-shown body of a device to be used with the optical reading sensor.

The sensor body 1 and the printed circuit board 11 having the electric processing circuit 10 mounted thereon are housed in a casing which is constructed by joining a pair of split casing halves 3. Of these, the upper casing half 3 is formed with a rectangular slot 14, from which projects a finger portion 1 5a of a control unit 15forcontrolling a switch element 10a in the aforementioned electric processing circuit 10, and hinges a hinged portion 15b ofthe control unit 15.

Fromthe right-hand end portions 3b ofthetwo split casing halves 3, on the other hand, there are formed cylindrical extensions 18, on which is fitted a joint cap l6tojoin thetwo split casing halves3 atthe right- hand end portions 3b. In those cylindrical extensions 18, moreover, there is fixed a cylindrical rubber member 17 into which is inserted the aforementioned cable 13.

The split casing halves 3 are formed at their lefthand end portions 3cwith extensions 3a so that heir left-hand end portions 3carve connected by means of an intermediate cap 4.

The afore-mentioned sensor body 1 will be described with reference to the exploded perspective view of Figure 1 (b). This sensor body 1 has its outer casing 19 constructed of a pair of upper and lowersplitcas- ing halves, which are integrated byfitting a plurality of depending walls 20,which are defined byengag- ing holes 20a formed in the upperoutercasing half 19, on retaining projections 21 which are formed in such positions on the lower outer casing half 19 asto correspond to the aforementioned engaging holes 20a.Moreover, the lower outer casing half 19 is formed in its upper right-hand portion with both a first accommodating recess 22 for accommodating a not-shown light emitting element such as an LED and a second accommodating recess 23 juxtaposed to theformerforaccommodating a not-shown light receiving element such as a phototransistor.The outer casing half 19 isfurtherformed in its upper central portion with a third accommodating recess 25 for accommodating an opticalfibre24.Thisthirdac- commodating recess 25 is bifurcated at its right-hand portion into two branches, of which one recess branch 25a guides a first branch 24a of the optical fibre 24 into the aforementioned first accommodating recess 22 whereas the other recess branch 25b guides a second branch 24b of the optical fibre 24 into the afore-mentioned second accommodating recess 23. As shown in Figure 2, on the other hand, both the left ends of the outer casing halves 19 are formed with elastic tips 27 in which a ball lens 26 is retained such that the opposite end 24c ofthe optical fibre 24 opposed to the aforementioned branches is arranged to face the innerface portion of the ball lens 26.

As has been described above, the ball lens 26 is resiliently supported by the tips 27 of the outercasing halves 19 acting as the support. These tips 27 are slit at 27a to increase the resilience of the tips 27. This results in forming the tips 27 with a plurality of members 27b which are defined by the slits 27a. These members 27b are formed symmetrically with respect to an optical axis e shown in Figure 2. Then, if the ball lens 26 issnuglyfitted in the tips 27, it can be aligned in the optical axis e with the optical fibre 24, because the ball lens 26 per se is made spherical to have a symmetric shape, so that a complicated optical aligning operation can be eliminated. Moreover, the ball lens 26 is retained in position by the elastic force of the elastic members 27b.

The second embodiment shown in Figures 3 and 4 is of the type inwhich an optical beam emitted from a lightemitting medium is received bya light receiving element 30 such as a phototransistorso that information may be read in terms ofthe optical change ofthe optical beam. The sensor body 1 is constructed such thatthe light receiving surface ofthe aforementioned light receiving element 30 connected electrically with a not-shown device to be used with the optical reading sensor is arranged on the bottom wall of a gener allycylindricalsupport31 and such thatthe ball lens 26 is elasticallysupported inthe open end ofthesupport31.

More specifically, the support 31 is formed in an innerwall at its open end with a spherical recess 32 which is contoured to snugly receive the ball lens 26, and is furtherformed with four slits 31 a which are cut from the open end to the bottom wall ofthe support 31 to form a corresponding number of resilient members 31 b symmetrically with respect to the optical axis C of the light receiving element 30.

As a result, if the symmetric ball lens 26 is driven into the afore-mentioned spherical recess 32 against the resilience ofthe members 31 b until it is snugly fitted in the support31, it is retained in the support31 in alignment with the optical axis e of the light receiving element 30.

The third embodiment shown in Figures Sand 6is an optical reading sensorwhich is constructed such that a light receiving element 40 such as a phototransistor and a light emitting element 41 such as an LED are arranged to face the ball lens 26 directly not through any optical fibre. The sensor body 1 is constructed of: a generally cuboid support 42; the aforementioned light receiving and emitting elements 40 and 41 arranged across partition 43 formed to project fromthebottomwallofthatsupport42; a depending leg 42a formed to depend from the support 42 and to bearing a terminal 40a forthe light receiving element 40, a terminal 41 a forthe light emitting element41 and a common terminal 44; and the ball lens26sup ported elastically in the open end ofthe support 42.

The afore-mentioned terminals 40a, 41 a and 44 are electrically connected with the body of a device to be used with the optical reading sensor.

The retaining structure ofthe ball lens 26 in this third embodiment is made similar two the foregoing first and second embodiments such that the support 42 is formed in its inside with a spherical recess 46 contoured to snugly receive the ball lens 26 and is further formed with four slits 42b cut from the open end to the bottom wall of the support42 to form a corresponding nu m ber of resilient members 42c symmetrically with respect to the optical axis e ofthe sensor body 1.

As a result, if the ball lens 26 is snugly fitted in the aforementioned spherical recess 46, it is retained re liablybythesupport42in alignmentwiththeoptical axis e ofthe sensor body 1.

The foregoing respective embodiments have been described by using the ball lens 26, but it will be app reciated that lenses having a shape otherthan spheri cal can be used.

In the foregoing respective embodiments, more overthe supports 19,31 and 42 are slit at 27a,31 a and 42b to form the resilient members 27b, 31 band 42c. It will, however, be appreciated that the shape, con struction and number of those slits be changed ac cording to the shape and construction of the sup ports and the lenses.

As has been described hereinbefore, it is possible to provide the optical reading sensor which can sup portthe lens by its supporteventhough it haste simple construction.

Claims (10)

1. An optical reading sensorfor receiving an optical beam,which is reflected from a medium carrying a recorded optical information, to detect an information signal,the sensorcomprising: a light emitting elementfordirecting an optical beam at said medium; a lens arranged for receiving and focusing the first-named optical beam reflected by said medium; a light receiving element for receiving the first-named optical beam focused by said lens; and an open-ended supportfor resiliently supporting said lens near its open end in alignment with said light receiving element so that said lens may guide its focused optical beam towards said light receiving element.

2. An optical reading sensor according to Claim 1, wherein said support is provided longitudinally extending slits near its open end to form a pluralityof resilient membersforsnugly accommodating said lens therein to retain the same in position.

3. An optical reading sensor according to Claim 2, wherein said support is tapered toward its open end so that said resilient members become thinner and narrowertowardsthe open end of said support.

4. An optical reading sensor according to Claim 2, wherein said support comprises a pair of casing halves which together form a casing for retaining said lens in position by the resilience of said resilient members and for accommodating said lightreceiv- ing memberwhen they are joined to each other.

5. An optical reading sensor according to Claim 2, wherein said support is generally of cylindrical configuration having a generally spherical recess in its open end for retaining said lens in position by the resilience of said resilient members.

6. An optical reading sensor according to Claim 2, wherein said support is generally of cuboid con- figuration having a generally spherical recess in its open end for retaining said lens in position by the resilience of said elastic members.

7. An optical reading sensor according to any preceding claim, wherein said lens is spherical.

8. An optical reading sensor substantially as hererin before described with reference to Figures 1 a to 2.

9. An optical reading sensor substantially as hereinbefore described with reference to Figures 3 and 4.

10. An optical reading sensor substantially as hereinbefore described with reference to Figures 5 and 6.