APPARATUS FOR SENSING THE PRESENCE OF A RECORD MEMBER

Abstract: An apparatus for sensing the presence of a record member (28) includes a protective member in the form of an opaque brush (48) which operates as a non-reflective shield to an optical sensor (60) to protect the sensor (60) against ambient light. The opaque brush (48) is engageable by the record member (28) to sweep across and clean the surface of the optical sensor (60) and to permit the presence of the record member (28) to be sensed.

Description: APPARATUS FOR SENSING THE PRESENCE OF A RECORD MEMBER Technical Field The present invention relates to an apparatus for sensing the presence of a record member and more particularly, but not exclusively, to a printing apparatus including optical sensing means having a surface across which the record member moves for sensing thereof. It is known for a printing apparatus to be provided with means for detecting the presence of a record member, such as a slip or form, as the record member is being inserted into position in the printer for the printing operation. A common mechanism for detecting the presence of the record member is an optical sensing arrangement which bridges the path of the record member and detects the presence thereof. An optical sensing arrangement is described in U.S. Patent No. 3,805,027 which relates to an optical reader apparatus having means for automatically cleaning the sensing end of a fiber optics probe. A resilient biasing element is positioned in the path of each record member, such as a document or card, and is biased to direct the forward end of the record member upwardly so that the sensing end of the probe is wiped by the leading edge of each record member being advanced. One of the disadvantages of the above automatic cleaning method is that ambient light may enter the sensing end of the probe when the record member is not present. Such ambient light may give rise to a false reading. In general, the presence of ambient light is particularly a problem when associated with optical sensing arrangements of printers. Disclosure of the Invention It is an object of the present invention to provide an apparatus for sensing the presence of a record member, the apparatus having an automatic cleaning facility for removing contamination from the surface of the sensor and for preventing ambient light entering the sensor when the record member is not present. Thus, according to the invention, there is provided an apparatus for sensing the presence of a record member, said apparatus including an optical sensing means having a surface across which said record member moves for the sensing thereof, characterized by sweep means supported in a housing and positioned to engage with the substantially cover said surface to inhibit ambient light from impinging thereon, said sweep means being engageable by said record member to cause said sweep means to sweep across and thereby clean said surface and to cause movement of said sweep means away from said surface to allow the presence of said record member to be sensed. In a preferred embodiment said sweep means is an opaque brush pivotally supported from said housing. Brief Description of the Drawing One example of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a plan view of a portion of the printer and showing the location of the optical sensor; Fig. 2 is a view taken along the line 2-2 of Fig. 1; Fig. 3 is an elevational view of a portion of a printer incorporating the subject matter of the present invention and illustrating the parts in a non- operating or dormant position; Fig. 4 is a similar view illustrating the parts in an operating position upon insertion of a slip or like document; Fig. 5 is a view of the brush supported in dormant position? and Fig. 6 is a view taken along the line 6-6 of Fig. 5. Best Mode for Carrying out the Invention Prior to describing the structure in detail, it should be noted that the printer with which the present embodiment is associated, and which is used in certain operations and/or environments, may be termed a slip or form printer for printing on documents of the slip or form type, which documents are normally inserted into the printer for the printing operations. Referring now to Figs. 1 and 2, these constitute a plan view and an end view, respectively, of a guide 10 for a slip or like document, which guide is for use in a slip printer (not shown). The slip guide 10 is a molded plastic part of unitary construction and has a brush assembly, generally designated as 12, secured to the surface 14 of the guide 10 at one corner thereof. The guide 10 includes a first straight flat portion 16 and a second straight flat portion 18 disposed at an angle to portion 16. A plurality of ribs, as at 20, connect the portions 16 and 18 with an upstanding portion 22. The brush assembly 12 is secured to the surface 14 of the first portion 16 and such assembly includes a housing 24 of generally rectangular shape which extends upwardly from the surface 14, the housing being generally perpendicular to the upper surface 14 and to a lower surface 26 of the portion 16. The surface 26 provides a path along and against which a slip or like document 28 (Fig. 4) is inserted for printing operation. Figs. 3 and 4 illustrate an elevational view taken in the direction A-A of Fig. 1. The housing 24 is preferably made of plastic material and includes side wall portions 30 and 32 (Fig. 2), a right side portion 34 (as viewed in Fig. 1) and an open left side portion 36. A cover 38 is secured to the top of the side wall portions 30 and 32 and to the top of the right side portion 34. The open left side portion 36 provides a window for access to a brush holder 40 which is pivotally supported in cradles 42 and 44 formed integral with the side wall portions 30 and 32. The brush holder 40 is generally cylindrically shaped and includes an opening 46 through which extends a brush 48 of opaque nylon material. The brush 48 includes a cap portion 50 which is captured by side portions 52 and 54 of the brush holder 40. The side portions 52 and 54 include lugs 53 and 55, as illustrated in Figs. 5 and 6, which engage the cap portion 50 and contain the brush in position in the brush holder 40. The brush holder 40 includes a flat surface portion 56 (Fig. 2) on the top thereof for receiving one end of a coil spring 58. The other end of the coil spring 58 engages the underside of the cover 38. The coil spring 58 urges or biases the brush holder 40 along with the brush 48 in a downward direction so as to maintain the brush holder 40 in contact with the cradles 42 and 44 of the housing 24. Figs. 3 and 4 show the positions of the brush holder 40, the brush 48, and an optical sensor 60 relative to an operation wherein the slip 28 or like document is inserted along the surface 26 of the guide 10. The optical sensor 60 contains both an illumination source and a detector element, and is available from TRW Optoelectronics Division and the brush is available from Schlegel Corporation. Suitable wiring, as at 64 and 66, is provided for the sensor 60, the operation of which is well-known in the optical sensing industry. As the slip 28 is placed into position to be sensed by the sensor 60 (Fig. 3), the brush 48 is in contact with the surface 68 of the sensor in a manner wherein the brush protects the sensor 60 from ambient light, which, in some environments, may be sufficient to indicate that a slip is being inserted into position for a printing operation when, in fact, a slip is not present. Fig. 4 shows the position of the slip 28 when engaging the brush 48 to cause the brush to be moved across or to sweep the surface 68 of the optical sensor 60. The brush 48, in effect, cleans the surface 68 of the sensor 60 so as to enable clear and accurate readings of the presence of the slip 28. The engagement of the slip 28 with the brush 48 causes the brush to be moved upwardly a slight amount while at the same time swinging in a clockwise direction, as seen in Fig. 4. While the member 48 is described above as a brush of opaque nylon material, other structures may include a foam-like element of porous, plastic material or a web-like element of felt or cloth material. It is, of course, a requirement that the member 48 be made of opaque (light absorbing) material. It is thus seen that herein shown and described is a record media sensing mechanism which provides for preventing false readings due to ambient light, for absorbing light from the illumination source at the time the slip or like document is not present for a printing operation, and for removing contamination from the surface of the sensor.

Claims: CLAIMS: 1. An apparatus for sensing the presence of a record member (28), said apparatus including an optical sensing means (60) having a surface (68) across which said record member (28) moves for the sensing thereof, characterized by sweep means (48) supported in a housing (240 and positioned to engage with and substantially cover said surface (68) to inhibit ambient light from impinging thereon, said sweep means (48) being engageable by said record member (28) to cause said sweep means (48) to sweep across and thereby clean said surface (68) and to cause movement of said sweep means (48) away from said surface (68) to allow the presence of said record member (28) to be sensed. 2. An apparatus according to claim 1, characterized in that cradle means (42, 44) is provided in said housing (24) for supporting said sweep means (48) to permit pivoting thereof. 3. An apparatus according to claim 1 or claim 2, characterized in that biasing means (58) is provided for biasing and sweep means (48) into contact with said surface (68) of said optical sensing means (60). 4. An apparatus according to any one of claims 1 to 3, characterized in that said sweep means (48) is in the form of an opaque member (48). 5. An apparatus according to claim 4, characterized in that said opaque member (48) is in the form of a brush (48).

Inventors: BRULL ROBERT A, BULLIVANT ROBERT F, DEL SIGNORE JAMES R II, WALKER ALAN H, BRULL, ROBERT, A., BULLIVANT, ROBERT, F., DEL SIGNORE, JAMES, R., II, WALKER, ALAN, H.
Applicants: NCR CO, NCR CORPORATION
Application year: 1989
Main classification: G06K7
IPC codes: B41J29, B65H7, G01V8, G02B27