GB2154746A

GB2154746A - Apparatus for detecting a physical quantity of a detection medium

Info

Publication number: GB2154746A
Application number: GB08501614A
Authority: GB
Inventors: Yasuhiro Yamada
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 1984-01-31
Filing date: 1985-01-23
Publication date: 1985-09-11
Also published as: DE3503121A1; GB8501614D0; JPS60159607A; DE3503121C2; HK51589A; GB2154746B

Abstract

An apparatus for detecting a physical quantity of a detection medium, comprises a sensor (18) for outputting a signal of a level corresponding to the physical quantity of the detection medium, a detecting circuit (13) for receiving the output signal of the sensor (18) and for outputting a result of detection of the physical quantity of the detection medium on the basis of the output signal of the sensor (18), a reference signal generating circuit (17) for generating at least one reference signal, a reference signal input circuit (11, 12, 14, 15, 16) for delivering a reference signal which is output from the reference signal generating circuit (17) in place of the output signal of the sensor (18), and an off-normal state detecting circuit (11, 19) for detecting an off-normal operation state of the detecting circuit (13) by a signal which is output from the detecting circuit when the reference signal is input. The physical quantity may be thickness, and the detection medium may be a banknote. <IMAGE>

Description

SPECIFICATION Apparatus for detecting a physical quantity of a detection medium This invention relates to an apparatus for detecting a physical quantity of a detection medium and, in particular, an improved detection apparatus which is suitable to detect a thickness of sheets such as bank notes on a sheet processing apparatus.

In general, with a sheet processing apparatus such as a currency transaction apparatus on an automatic cash dispenser, etc., it is difficult to withdraw bank notes in designated numbers. Usually, a thickness detection apparatus are employed to detect a multiple feed such as a double feed of bank notes when they are withdrawn from the cash dispenser.

A thickness detection apparatus having an arrangement shown in Fig. 1 is known in the art. In this apparatus, a thickness sensor 1 is arranged on a conveying path immediately after a bank note withdrawal section and an output signal from the sensor 1 is input to a thickness detecting circuit. The thickness detecting circuit 2 is operated by a control signal which is sent through a latch circuit 4 from a CPU (central processing unit) 3 which serves as a main control section on the currency transaction apparatus. For example, an output signal of the sensor 1 is compared with a predetermined reference signal and, when the output of the sensor 1 is compared with the reference signal, a high level signal is sent as off-normal thickness data to CPU 3 through a latch circuit 5. CPU 3 checks the contents of the latch circuit 5 to see whether or not there is any multiple feed of bank notes.

However, in the conventional thickness detecting apparatus, even if any off-normal state occurs in the operation of the thickness detecting circuit 2, no means is provided for checking it and it is not possible to accurately detect such an off-normal states to the thickness of the bank notes, failing to constantly obtain a designated number of bank notes.

It is accordingly an object of this invention to provide a new and improved apparatus for detecting a physical quantity of a detection medium, which can check off-normal states in the operation of a detecting means and can accurately detect a physical quantity of a detection medium.

According to this invention, an apparatus for detecting a physical quantity of a detection medium, comprising: a sensor for outputting a signal of a level corresponding to the physical quantity of the detection medium: a detecting means for receiving the output signal of the sensor and for outputting a result of detection of the physical quantity of the detection medium on the basis of the output signal; a reference signal generating means for generating at least one of reference signals; a reference signal input means for permitting the reference signal which is output from the reference signal generating means to be received therein in place of the output signal of the sensor; and an off-normal state detecting means for detecting an off-normal state in the operation of the detecting means by the signal which is output from the detecting means when the reference signal is received.

According to the present invention, in order to achieve the above-mentioned object, at least one reference signal is input to the detecting circuit in place of an output signal of the thickness detecting sensor to permit the operation of the detecting means to be tested.

These are other objects and features of this invention can be understood by reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic view showing a conventional thickness detecting apparatus; Fig. 2 is a schematic view showing an apparatus according to an embodiment of this invention; Fig. 3 is a perspective view showing a detail of a sensor mechanism as used in the embodiment of this invention; Fig. 4 is a plan view showing a major section in Fig. 3; Fig. 5 is a characteristic view showing a relation of a rotation angle of a potentiometer in Fig. 3 to an output thereof; Fig. 6 is a circuit diagram showing a detail of an electric circuit section for detecting the thickness of a detection medium by the output of the potentiometer in Fig. 3; Fig. 7 is a timing chart for explaining the operation of the electric circuit in Fig. 6;; Fig. 8 is a circuit arrangement showing a detail of a thickness detecting circuit in Fig. 2; and Fig. 9 is a timing chart for explaining a checking operation in Fig. 2.

An embodiment of this invention will be explained below by referring to the accompanying drawings sheet.

In Fig. 2, reference numeral 11 shows a CPU (central processing unit) for controlling a main control section of a currency transaction apparatus. A thickness detecting circuit 1 3 is controlled by CPU 11 through a latch circuit 1 2. CPU 11 sends control signals C1, C2 and C3 to relays 14" 142 and 143, respectively, through the latch circuit 1 2 to energize these relays. A contact 1 6 of the relay 15, is connected to an output terminal 1 7H for outputting a high level reference voltage VH of a reference voltage generating circuit 1 7 and a contact 1 63 of the relay 1 52 is connected to an output terminal 17, for outputting a low level reference voltage V,.A contact 1 63 of the relay 1 53 is connected to an output terminal of a thickness sensor 18, as set out below, on a conveying path immediately after a bank note withdrawal section. The high level reference voltage VH, low level reference voltage V, and output of the sensor 18 are switched by the control signals C1, C2 and C3, respectively, sent from CPU 11, so that they are selectively input to the thickness detecting circuit 1 3. The thickness detecting circuit 1 3 provides three kinds of outputs in accordance with the level changes of the input signals.With the input signal at a high level, the thickness detecting circuit 1 3 produces an output signal S1 of a "1" level and with the input signal at a low level, the thickness detecting circuit 1 3 produces an output signal S2 of a low level. When the input signal has a level of a reference voltage (a predetermined voltage) corresponding to the thickness of a single sheet of a bank note, the thickness detecting circuit 1 3 produces output signals S1 and S2 of a "0" level.These output signals are supplied to CPU 11 through a latch circuit 1 9. Suppose that the thickness detecting circuit 1 3 receives the reference signal VH of a high level or the reference signal VL of a low level as an input signal as set out below. If, in this case, the output signals S1 and S2 are not at the "1" level, the thickness detecting circuit 1 3 is judged as being in the off-normal operation state.

Figs. 3 to 7 show a detail of the thickness detecting sensor 1 8. In a sensor mechanism of Fig. 3, reference numeral 31 shows a conveying path for conveying a bank note 32, as a sheet, in a longitudinal direction with an upright posture. The conveying path 31 comprises a pair of parallel conveying belts 34, 34 entrained over belt support rollers 33 ....

and a pair of conveying belts 35, 35 entrained in place such that they are in partial contact with the conveying belts 34, 34. The bank note 32 is conveyed with its upper and lower longitudinal side sections sandwitched between the conveying belts (34, 35). The thickness reference member 36 is located in close proximity to the conveying path 31 and is comprised of a non-rotatable roller fixed to a support (37, 37) around which the belt support roller (33, 33) is rotatably supported, noting that the conveying belts 34, 34, 35, 35 are run over the belt support rollers 33, 33.

A detection lever 40 contacts at one end with the thickness reference member (hereinafter referred to as a thickness reference roller) 36 and is swingably mounted with a support shaft 38 as a center as shown in Fig. 4, such that it is clockwise, urged normally under a very weak force of a spring 39. When the bank note 32 reaches the thickness reference roller 36, one end 40a of the detection lever 40 is cleared in a direction of the thickness of the bank note 32 and the detection lever 40 is swingably displaced in a counterclockwise direction with the support shaft 38 as a center. A guide plate 43 as shown in Fig. 4 is adapted to prevent the detection lever 40 from being cleared by the bank note 32 at a location other than a point of contact with the reference roller 36. The detection lever 40 is mounted on a rotation shaft of a potentiometer 41 supported by supporting columns 42.

The motion of the lever 40 is transmitted as a rotation angle displacement to the potentiometer 41, whereby an output proportional to the rotation angle displacement can be obtained from the potentiometer 41. That is, the following equation holds: T = LsinS where T : the thickness of the bank note; L : the length of the detection lever; and B : the rotation angle of the potentiometer.

Where, here, the rotation angle H is smaller, then T =LO The rotation of the potentiometer 41 becomes proportional to the thickness of the bank note.

Fig. 5 shows a relation of the rotation angle of the potentiometer to the output thereof.

Fig. 6 shows a sensor circuit for detecting an off-normal state including a state of bank notes, such as a double feed, torn hole and tapes thereon, by the output of the potentiometer 41 in the sensor mechanism. In Fig. 6, reference numeral 41 shows an equivalent circuit of the potentiometer comprised of magnetoresistive elements R", R,2. The resistive values of the magnetoresistive elements R" and R12 vary in accordance with the rotation angle displacement. Both the terminals of the potentiometer 41 are connected to the positive and negative terminals + V and - V, and a potential on a junction between the magnetoresistive elements R" and R,2 is supplied through a resistor R1 to one input terminal of an operational amplifier which is operated through a power source (+ V, - V).A predetermined potential is supplied to the other input terminal by a reference potential generating circuit comprised of resistors R2 to R4. A comparison output of the operational amplifier 44 is fed to one input terminal of an operational amplifier 45 of the next stage through a resistor R6 and is fed back to the one input terminal of the operational amplifier 44 through a variable resistor R5 for initialization.

The other input terminal of the operational amplifier 45 is grounded through a capacitor C and is connected to one terminal of a switch SW where a control signal S is supplied through a resistor R,o for high frequency cutting. The output of the operational amplifier 45 is fed back to the one input terminal through a feedback resistor R7 and is supplied to one input terminal of an operational amplifier 46 through a resistor R8. The other input terminal of the operational amplifier 46 is grounded and an output of the operational amplifier 46 is fed back to the one input terminal thereof and is connected to the other terminal of the switch SW.

The operation of the sensor 1 8 and associated circuit will be explained below by referring to a timing chart in Fig. 7.

When the bank note reaches the detection position of the potentiometer 41, the output of the potentiometer 41 varies from a low to a high level. In Fig. 7, the switch SW is kept in an "opened" state during a time period of a timing cycle from prior to the detection of the bank note by the potentiometer 41 until after such detection has been completed, noting that during the other time period of the timing cycle the switch SW is in the "closed" state.

The control signal S is used to set the switch opening/closing timing. For example, first and second photosensors (not shown) are each comprised of a pair of a light-emitting element and light-receiving element and are provided one at the upstream side and one at the downstream side of the conveying path 31 with the reference roller 36 as a reference so as to detect the passage of the bank note.

In this case, it is only necessary to obtain a logical sum of the outputs of the first and second photosensors. Alternatively, a photosensor (not shown) may be provided at a forward section of the conveying path with the reference roller 36 as a reference so as to detect the passage of the bank note. In this case, a time at which the switch SW is switched from the "closed" to the "opened" state is detected by the output of the photosensor and the switch SW is switched from the "opened" to the "closed" state by a delayed replica of an output of the photosensor.

The gain of the operational amplifier 45 is set by the variable resistor R5 to a state in which the bank note is not detected. Since the switch SW is in the "closed" state at the time at which the bank note is not detected, charges are stored in the capacitor C by the output of the operational amplifier 46. When the photosensor detects the bank note, the switch SW is in the "opened" state and the capacitor C maintains its charged level. Upon the detection of the bank note by the detection level, the values of the magnetoresistive elements Rill, R12 vary, causing the output of the operational amplifier 44 to be reversed.

The output of the operational amplifier 44 is compared by the operational amplifier 45 with the charged voltage on the capacitor C to obtain a comparison output OUT from the operational amplifier 45. Upon the detection of the bank note, the charged voltage on the capacitor is greater than the output of the operational amplifier 44, obtaining an output signal OUT of a high level. Now suppose that an extraneous thing such as a sticking tape is attached to the bank note. In this case, an offnormal state can be identified on the output OUT due to a rise in the level of the output OUT as indicated by AD in Fig. 7C upon the detection of the bank note. Now suppose that the bank notes are fed one over the other in a superimposed fashion.In this case, the output signal OUT rises as a detection level for a "double feed" and falls as a nondetected (low) level for a "worn" hole. It will be noted that a spike-like rise of the output signal OUT in an initial detection phase of the bank note is due to the clearing of the detection lever 40 upon the detection of the longitudinal sides of the bank notes.

According to the sensor 18, since the operational amplifier 45 compares an output on the potentiometer 41 when the bank note is detected with an output when the bank note is not detected, even if the rotation angle 8 of the potentiometer and thus its output vary as shown in Fig. 5 due to the wear of the reference roller 36 or the one end 40 of the detection lever 40 on account of its prolonged usage, it is still possible to accurately detect the thickness of the bank notes through a correction step.

Fig. 8 shows a detail of the thickness determining circuit 1 3 adapted to selectively receive an output signal from the sensor 1 8.

That is, the thickness determining circuit 1 3 comprises two operational amplifiers 51, 52 and reference voltage supply 53 and are adapted to supply output signals S1 and S2 corresponding to an input signal.

The checking operation of the thickness detecting circuit 1 3 of Fig. 2 will be explained below by referring to a timing chart of Fig. 9.

First, CPU 11 sends a control signal Cl as shown in Fig. 9A to the relay 15, to permit a high level reference voltage VH as indicated by I in Fig. 9D to be input to the thickness detecting circuit 1 3 through the energization of the relay 151, and checks whether or not an output signal S1 as shown in Fig. 9B is a "1" level. With the signal S1 at the ''1'' level, the operation state is judged as being a normal state and with the signal S1 not at the "1" level, the operation state is judged as being the first off-normal state. When the operation state is judged as being the normal state as the result of checking by the control signal, a control signal C2 as shown in Fig.

9B is sent to the relay 1 52 to permit a reference voltage V, of a low level as indicated by II in Fig. 9D to be input to the thickness determining circuit 1 3. At this time, check is made as to whether or not the output signal S2 as shown in Fig. 9F is at the "1" level.

With the signal S2 at the "1" level, the operation state is judged as being the "1" level and with the signal S2 not at the "1" level. the operation state is judged as being the second off-normal state. If the operation state is judged as being the normal state as the result of such checking, a control signal C3 as shown in Fig. 9C is supplied to the relay 1 53, causing the latter to be energized and permitting a ready state at which an output signal of the sensor 18 as indicated by Ill in Fig. 9D is input to the thickness detecting circuit 1 3 to permit a normal thickness detection. In this connection, it is to be noted that such testing is carried out, for example, for one transaction.

Although explanation has been given of the case where, in the above-mentioned embodiment, the operation test of the thickness determining circuit is carried out by inputting two reference signals of a different level to the thickness determining signal, this invention is not restricted to this embodiment. For example, this invention may be achieved by at least one reference signal.

Although in the above-mentioned embodiment, this invention has been explained as being applied to the thickness detecting apparatus for detecting the presence or absence of a multiple feed of bank notes, this invention is not restricted thereto, For example, this invention can be applied to an apparatus for detecting a physical quantity of a detection medium, such as the thickness, width, etc., of the other types of sheets.

According to this invention, it is possible to check the presence or absence of any offnormal state in the operation of the detecting means and to accurately detect a physical quantity of a detection medium.

Claims

1. An apparatus for detecting a physical quantity of a detection medium, comprising: a sensor for generating an output signal corresponding to the physical quantity of a detection medium; a detecting means for receiving an output signal of the sensor and for outputting a result of detection of the physical quantity of the detection medium, on the basis of the output signal; a reference signal generating means for generating at least one reference signal; a reference signal input means for inputting the reference signal, which is output from the reference signal generating means, to the detecting means in place of the output signal of the sensor; and an off-normal state detecting means for detecting an off-normal operation state of the detecting means by a signal which is output from the detecting means when the reference signal is input.

2. An apparatus according to claim 1, in which said physical quantity of said detection medium is the thickness of sheets.

3. An apparatus according to claim 1, in which said detection medium is a bank note.

4. An apparatus according to claim 1, in which said reference signal generating means is adapted to generate a plurality of reference signals of a different level.

5. An apparatus according to claim 1, in which said reference signal input means is adapted to deliver said reference signal to said detecting means before said physical quantity of said detection medium is detected.

6. An apparatus according to claim 1, in which said detecting means is adapted to deliver three kinds of results of detection in accordance with a high level, low level and set reference level corresponding to the output signals from the sensor.

7. An apparatus for detecting a physical quantity of a detection medium, substantially as hereinbefore described with reference to Figs. 2 to 9 of the accompanying drawings.