[0001] The present invention relates to an arrangement for controlled transportation of
sheet-like material, such as bank-notes. The arrangement includes means for transporting
sheets along a transport path, past optical detectors which detect the presence/absence
of sheets in the transport means. The detectors include a detector signal transmitter
and a detector signal receiver and are so arranged that a detector signal path extends
twice through the transport path.
[0002] It is known to use optical detectors adjacent bank-note transportation paths in,
e.g., bank-note handling systems to count and detect bank-notes. In this regard, problems
have occurred in transilluminating bank-notes of given currencies and denominations.
In addition, problems have occurred in trimming the level of a light-emitting diode
included in the detectors. Thus, when constructing an arrangement of the kind defined
in the introduction, problems have occurred in achieving the requisite reliability
in operation, particularly in combination with desired compact construction of the
arrangement components.
[0003] An object of the present invention is to avoid these problems.
[0004] To this end, it is proposed in accordance with the invention that the transportation
means of a transportation arrangement of the aforedescribed kind have the form of
transport bands, rollers or like devices for transporting sheets along the transportation
path in the close proximity of a rotating guide roller which is provided with a circular
prism in the region of its periphery; and that the detectors are disposed closely
adjacent to the transport path but on the side thereof that lies opposite the circular
prism.
[0005] According to one advantageous embodiment of the invention, the detectors with signal
transmitter and receiver are so arranged in relation to the rotating guide roller
that part of a signal path will have an extension through the peripheral region of
the guide roller and parallel with the rotational axis of said roller.
[0006] The invention will now be described in more detail with reference to the accompanying
drawings, in which
- Figure 1
- illustrates schematically and in side view part of an arrangement for transporting
sheet-like material constructed in accordance with the invention; and
- Figure 2
- illustrates the arrangement of Figure 1 from beneath, partly in section taken on the
lines II-II in Figure 1.
[0007] Figure 1 illustrates that part of the transportation arrangement which is essential
to the invention. The illustrated arrangement includes transport means 10 in the form
of two coacting transport bands 101, 102 which transport therebetween sheets (bank-notes)
along a transport path and past detectors 111, 112. In the illustrated case, the detectors
are mounted on a circuit board 11 and function to detect optically the presence/absence
of sheets in the transport means, i.e. between the transport bands 101, 102, as they
pass around a guide roller 103 forming part of the transportation arrangement. The
detectors 111, 112 include a light transmitter 111 (Figure 2) and a light receiver
112, the light transmitter 111 being hidden by the light receiver 112 in the Figure
1 illustration. The roller 103 is provided with a circular prism 1031 which extends
circumferentially around the roller at the periphery thereof, and the transport bands
or belts 101, 102 pass around the periphery of said roller 103. The roller 103 is
intended to be rotated anti-clockwise (see the two arrows in Figure 1).
[0008] The circuit board 11 is attached to an acrylic plate 12. Light from the transmitter
111 (suitably an IR-diode) follows a signal path through the plate 12 and through
the sheet (the bank-note), when a sheet is located between the bands 101, 102 passing
around the roller 103, and is reflected twice in the prism 1031, more specifically
against its conical end surface parts 1032, and finally reaches the receiver 112.
This is shown clearly in Figure 2, in which a transported sheet is referenced 2. The
signal path 113 is shown in Figure 2 and marked with two arrows. The transmitter 111
and the receiver 112 are placed outside the edges of the transport bands 101, 102
on that side of the transport path which lies opposite to the guide roller 103. The
signal path will thus pass twice through the transport path and in the region between
the end surface parts 1032 passes parallel with the rotational axis of the guide roller
103 and the prism 1031, as shown in Figure 2.
[0009] In the case of the inventive arrangement, the signal path is broken twice by passing
sheets 2. This minimizes the influence of semi-transparent sheets or bank-notes and
also eliminates the risk of, e.g., a bank-note passing a sensor placed close to the
centre of the bank-note path unnoticed. Furthermore, all electronics can be placed
on one and the same side of the bank-note path, thereby minimizing the number of circuit
boards and cables. When the receiver 112 incorporates a drive for the transmitter
111, the arrangement will be sensitive solely to its own light, i.e. will be insensitive
to ambient light. In addition to achieving good reliability in operation, a saving
in space can be achieved in accordance with the invention by fitting the requisite
prism to an existing guide roller.
1. An arrangement for controlled transportation of sheet-like material, such as bank-notes,
comprising transport means (10) for transporting sheets along a transport path past
detectors (111, 112) for detecting optically the presence/absence of sheets in the
transport means (10), wherein the detectors (111, 112) include a detector signal transmitter
(111) and detector signal receiver (112) and are so disposed that a detector signal
path extends twice through the transport path, characterized in that the transport means (10) include transport bands, belts, rollers or like
devices (101, 102, 103) for transporting sheets along the transport path in the close
proximity of a rotating guide roller (103) which is provided with a circular prism
(1031) in its peripheral region; and in that the detectors (111, 112) are disposed
in the close proximity of the transport path but on the side thereof opposite to the
circular prism (1031).
2. An arrangement according to Claim 1, characterized in that the detectors (111, 112) with signal transmitter (111) and receiver (112)
are so arranged in relation to the rotating guide roller (103) that a part of the
signal path has an extension through the peripheral region of the guide roller (103)
and extends parallel with the rotational axis of the guide roller (103).
