FR2769011A1 - Optical detector for paper handler used for double-sided scanning or printing - Google Patents

Abstract

The paper is carried by a rotating drum (13) carrying a circumferential optical track (36) formed with bands having differing coefficients of reflection. An optical detector (34) has a light source (40) directed onto the optical track and a photosensitive cell (41) receiving light reflected from the track. The signal (S1) from the detector is delivered to a controller and used to control operation of the drum and to detect anomalies in its operation.

Description

 The invention relates to a sheet processing device of the type comprising an assembly movable in rotation relative to a fixed base. Such a device can for example constitute the infrastructure of an office automation machine, more particularly a scanner or a printer, capable of carrying out recto / verso processing of such a sheet. In this case, the mobile assembly houses a processing unit and a sheet guiding arrangement defining a processing path passing opposite said processing unit. By rotation of the movable assembly, it is possible to place the processing unit in one or the other of two predetermined positions relative to said processing path, allowing recto / verso processing of the sheet.

 The invention relates more particularly to an improvement making it possible at the same time to know the state of the mobile assembly, in particular its position, even if the latter is stationary, to detect and / or control its movement and, if necessary, to detect an operating anomaly.

 There is known a device of the type indicated above adapted to operate a recto / verso treatment of a sheet, that is to say a treatment on each of the faces of the sheet. As indicated, the processing can, for example, be a reading of the information carried on said sheet or on the contrary a front / back printing of such a sheet. For example, document JP 63-136762 describes a processing device comprising several sheet access arrangements arranged on either side of a rotating movable assembly. This houses a guide defining a path for the passage of a sheet and a processing unit installed on the side of this guide. After a treatment in recto mode, a rotation of 1800 of this movable assembly allows the reversal of the treatment unit with respect to the path and consequently a treatment in verso mode by reversing the direction of movement of the sheet. By "sheet access arrangement" is meant any equipment constituting a means of entry of the sheet, making it possible to introduce the latter into the movable assembly or an outlet means making it possible to extract it, or else a input / output means making it possible, depending on the operating mode selected, to extract a sheet from the processing space and then reinsert it. Such an input / output means can thus be used to temporarily store a sheet after a treatment in recto mode, outside of the moving assembly while the latter goes into the treatment position verso and to reintroduce the same sheet in the mobile equipment to allow its treatment in reverse mode.

 For example, such a sheet processing device can be equipped with two input / output means generally located on either side of the moving moving element. It can also include an input means, optionally equipped with an automatic sheet feeding device, an input / output means located opposite this input means with respect to the moving assembly for recovering and temporarily store the sheet after its treatment in recto mode and an output means for evacuating the sheet reintroduced into the moving assembly, after its treatment in verso mode.

 As these sheet access arrangements are generally integral with the same base itself supporting the rotary mobile assembly, there is necessarily an interstitial functional clearance space at the periphery of the mobile assembly (the latter generally having a cylindrical shape). The presence of such an interstitial space can be the cause of operating anomalies if a leaf engages in it instead of following its normal path along the path defined in the moving assembly.

To control the condition of the moving part in one or other of its treatment positions, to control and / or order the movement of
The moving equipment from one position to another or even to detect an operating anomaly as indicated above, it is possible to use different systems and sensors using different techniques of electromagnetic, electromechanical, optical detection, etc. ..

 We know, for example, the use of optical encoders to detect the position and speed of a moving part when it is moving. Such optical encoders include bands bearing marks or symbols placed on the periphery of the moving assembly or on a disc driven in rotation at the same time as the latter. However, the use of such a system becomes complex when it comes to determining the position of a stationary moving assembly. It is then necessary to provide marks of alphanumeric type, which can only be read by a detector of a very sophisticated technology and therefore expensive.

 If the number of positions to be determined is small, several simple optical detectors can be used and the information provided by them can be combined. It is nevertheless necessary to provide several optical detectors at the periphery of the movable assembly, which increases the manufacturing costs and decreases the reliability of the assembly.

 The main object of the invention is to use a simple optical detector (that is to say a transmitter-receiver pair) in such a device for processing sheets with a moving moving element and which is capable of delivering usable information. to control the position of the moving element, in particular when the latter has reached one or other of its treatment positions, to detect and / or control the rotation of the mobile element from a treatment position to another and to detect, if necessary, an operating anomaly of the kind indicated above to develop corresponding information and preferably a signal used to stop the moving equipment.

 The basic idea of the invention consists in associating with such a transmitter-receiver couple an optical track arranged so as to be able to be scanned during a rotation of the mobile assembly and having an optical property having different values on predetermined ranges of said track.

 More specifically, the invention relates to a device for processing sheets of the type comprising an assembly movable in rotation relative to a base and capable of taking several different predetermined processing positions, comprising an optical detection unit and an optical track arranged opposite of said unit so that it can be scanned by it, characterized in that said optical track has an optical property having different values over predetermined ranges from these, certain ranges being representative of the aforementioned processing positions of said moving equipment and in that 'it further comprises means for processing and exploiting the signals delivered by said optical detection unit, for controlling said mobile assembly and / or detecting operating anomalies.

In a preferred embodiment, the optical property mentioned above is reflection. Consequently, adjacent areas of said track will have different reflection coefficients. This makes it possible to use an optical detector (that is to say a transmitter-receiver pair) of an extremely simple design, constituted by a light source and a photosensitive sensor, said source and said sensor being oriented so as to be coupled one to the other by light reflection on said track. In a simple way,
The detection unit is installed on the base while the optical track is installed on a mobile part whose displacement is representative of the rotation of the mobile equipment. Thus, for example, the optical track can be installed on a rotary element forming part of the training system of the moving assembly. Most often, said optical track is simply installed on the mobile assembly itself.

 With regard to detecting one or the other of the two treatment positions of the moving assembly, such a track may include two extreme ranges corresponding to these two treatment positions and having respectively two predetermined and different reflection coefficients l ' one of the other.

 Between these two extreme ranges1 the track may include a series of intermediate ranges having at least two other predetermined and different reflection coefficients alternately succeeding from one extreme range to the other. This series of intermediate ranges will make it possible to detect, control and possibly order the movement of the mobile assembly from one of its treatment positions to the other. In this case, the two reflection coefficients corresponding to the two aforementioned processing positions may be respectively a maximum reflection coefficient and a minimum reflection coefficient while the other two reflection coefficients may be two different intermediate coefficients lying in the interval defined by said minimum and maximum reflection coefficients.

 In addition, the signal supplied by the optical detection unit can be used to detect an operating anomaly such as the engagement of a sheet in the aforementioned interstitial space. Indeed, if, during the rotation of the moving element, a sheet engages in this interstitial space until it comes to be placed between the detection unit and the optical track, the corresponding electrical signal delivered by said detection unit optics is transformed into a constant level (corresponding to the reflection coefficient of the sheet) and no longer a succession of two levels corresponding respectively to the two intermediate reflection coefficients. The detection of such an event is interpreted as aforementioned operating anomaly and gives rise to the emission of an alarm signal and preferably to the production of a stop order for the drive motor of the mobile equipment.

 In other circumstances, if the moving element is in one or the other of the processing positions and if a variation in the electrical signal is recorded, this means that the sheet has just engaged in the interstitial space. The detection of this event is interpreted as another operating anomaly and gives rise to the emission of an alarm signal and preferably to the preparation of a stop order for the engine of an access arrangement concerned.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of a sheet processing device in accordance with its principle, given solely by way of example and made in reference to the nonlimiting drawings annexed in which:
- Figure 1 is a schematic sectional view of a sheet processing device equipped according to the invention, shown in the front processing position;
- Figure 2 is a view similar to Figure 1, the device being shown during the rotation of the movable assembly from a front processing position to a back processing position;
- Figure 3 is a view similar to Figure 1, the device being shown in reverse processing position;
- Figure 4 shows schematically the optical system fitted to the device;
- Figure 5 is a detail view of the track of this optical system;
- Figure 6 is a graph showing the different levels and waveforms provided by the optical detection unit;
- Figure 7 is a view similar to Figure 1, the device being shown when a malfunction resulting from improper engagement of the sheet is likely to be detected;
- Figure 8 is a block diagram of the electronic circuits fitted to the sheet processing device;
- Figure 9 is a flowchart illustrating the operation of the device during a position detection sequence according to the invention; and
- Figure 10 is a flowchart illustrating the operation of the device during a sequence of detection of operating anomalies.

Considering more particularly FIGS. 1 to 6, a sheet processing device II has been shown comprising a moving element 13 of generally cylindrical shape, mounted to rotate around a main axis.
O, horizontal and driven in rotation by a motor 15 of the stepping type. The axis of rotation O of the mobile assembly is carried by a fixed base 17 which houses the motor. This base also serves as a support for two sheet access arrangements 19, 21, namely here two input-output means mainly comprising drive rollers driven by respective motors (not shown). More specifically, the access arrangement 19 comprises two drive rollers 24 substantially in tangential contact between which a sheet 25 is capable of being introduced. One of the rollers is driven by the electric motor. The other access arrangement 21 is similar; it comprises two drive rollers 26 substantially in tangential contact. The two access arrangements 19, 21 are located on either side of the movable assembly 13. The latter houses a processing unit 27 and a sheet guide arrangement 28 defining at least part of a path processing 30 of such a sheet passing opposite the processing unit. Other parts of this processing path can be materialized by guides located outside the movable assembly, in the vicinity of the access arrangements. The processing unit 27 can comprise or constitute a read head and in this case, the device is part of an office automation machine constituting or comprising a document scanner.

The processing unit can also comprise or constitute a printing means, for example of the thermal transfer or inkjet type and in this case, the sheet processing device forms part or essentially constitutes a printer. Of course, such a sheet processing device can be integrated into a fax machine, a microcomputer or a peripheral thereof. It can advantageously be equipped with means for connection to a computer.

The sheet processing device as described so far is conventional, in particular for a recto / verso processing of said sheets since the rotation of the movable assembly makes it possible to place the processing unit in one or the other of two predetermined processing positions shown in Figures 1 and 3, respectively. The front / back processing is then carried out as follows. A sheet 25 is engaged in the access arrangement 19 and moves along the processing path 30 defined inside the movable assembly (FIG. 1). The recto treatment is performed during this journey. At the exit of the moving element, the sheet is taken up by the access arrangement 21 until it is completely extracted from the moving element. The rollers 26 are stopped so that the sheet remains on standby in the position illustrated in FIG. 2. At this time,
The mobile assembly is rotated, as shown in FIG. 2, until the processing unit occupies the position illustrated in FIG. 3, the path 30 defined inside the mobile assembly being at again disposed between the two input-output means. At this time, the access arrangement 21 is actuated in the opposite direction, so as to re-engage the sheet 25 inside the moving assembly, along the path 30, to pass again opposite the unit. 27 and undergo a back treatment. The sheet 25 is then taken up by the rollers 24 and returned to the user.

The invention relates more particularly to the means making it possible to determine and stabilize the two treatment positions of FIGS. 1 and 3, while controlling the rotation of the mobile assembly 13 when the latter moves from one treatment position to another. To do this, the device is equipped with an optical detection unit 34 and an optical track 36 arranged opposite said unit so that it can be scanned by that during a rotation of the moving element 13. In the 'example, the optical detection unit is fixed to the base 17 while the optical track is secured to the moving element. Preferably, as shown, the optical detection unit and the optical track are located on either side of an interstitial functional play space 38 formed at the periphery of the movable assembly 13 between it and
the base 17. The optical track 36 has an optical property having different values over predetermined ranges 37376 thereof. In
The occurrence, the optical property in question here is reflection; therefore, said predetermined ranges have different reflection coefficients. As can be seen in FIGS. 1 to 4, the optical track 36 is a kind of strip which is wound in an arc of a circle at the periphery of the cylindrical moving element 13. The adjacent areas having different reflection coefficients are sections of this strip defining two extreme areas 37a, 37d corresponding to the two front and back processing positions and a series of intermediate areas 37fez 37c, succeeding each other between said end areas, and having at least two other predetermined and different reflection coefficients alternately succeeding on said track. In the example, the two reflection coefficients of the extreme ranges 37a, 37d, that is to say those which correspond to the two processing positions front and back are a maximum reflection coefficient a for the range 37a and a coefficient of minimum reflection g for the range 37d. The other two reflection coefficients t and c lie in the interval defined by said minimum and maximum reflection coefficients.

The optical detection unit 34 comprises, for its part, a light source 40 and a photosensitive sensor 41 oriented to be coupled to each other by light reflection on said track 36. In other words, the signal S1 available at the output of the photosensitive sensor depends on the reflection coefficient of the range which is opposite the optical detection unit at a given time. If we consider for example the operating phase during which the moving element rotates from one processing position to another, the signal S1 varies in accordance with the graph in FIG. 6. In fact, if we consider that in the position recto processing, the detection unit 34 is opposite the extreme range 37ê having the maximum reflection coefficient a, the signal S1 is maximum S1a as long as the detection unit is located opposite this range then, as soon as the moving element 13 begins to rotate, the signal S1 evolves between two different values S1b, S1ç, both less than the value SIa. These two values correspond to the reflection coefficients b and ç of the intermediate ranges 37b, 37ç. Then, when the moving element arrives at the back processing position, the signal S1 has a value Sld lower than all the previous ones. This minimum value corresponds to the minimum reflection coefficient d of the other extreme range 37d defined at the other end of the track 36.

 It should be noted that, since the signal S1 is an electrical voltage delivered by a photosensitive sensor, this voltage exists and has a well-defined value as soon as the light beam emitted by the source is reflected on one of the ranges of Track. Consequently, the signal S1 exists and has a predetermined stable value even if the moving element is stopped, in particular in one or the other of its processing positions. On the other hand, any movement of the moving assembly results in the appearance of a signal in slots as visible in FIG. 4. For a rotation at constant speed, said signal in slots presents a constant frequency as soon as the ranges intermediates 37t, 37ç all have the same length as shown in FIGS. 4 and 5. However, it may be advantageous to ensure that the lengths of said intermediate ranges 37k, 37ç (length is understood to mean the dimension of such a range according to the direction of relative movement between the track 36 and the optical detection unit 34) vary according to a predetermined progression law. For example, the length of adjacent beaches could decrease or gradually increase from one extreme beach to another.

 This would result, at constant speed, a signal in slots of variable frequency during the rotation of the moving element. The frequency would increase or decrease depending on the direction of rotation thereof. This characteristic could be used to determine the direction of rotation of the moving assembly. This would provide information that is particularly useful when starting up or returning to service (after user intervention following an operating anomaly) of the device. It may indeed happen that in such circumstances, the moving element 13 is not in one or the other of its operating positions. Restarting therefore involves repositioning the moving equipment. Analysis of the direction of variation of the frequency of the signal S1 would make it possible to know to which processing position the moving element is moving and to reverse the direction of rotation of the motor 17, if necessary, if this processing position does not is not what is desired for the next steps. It should also be noted that the square-wave signal can also constitute feedback information for controlling the motor in order to better control the movement and the speed of the moving element during its rotation.

 The sheet processing device further comprises means for processing and processing the signals delivered by the detection unit 34 for controlling the moving element 13 and in particular the stabilization of the latter in one or more 'other of its processing positions but also, as will be seen below, for the detection of certain operating anomalies. The processing and operating means will now be described with reference to FIG. 8 which represents the electronic circuits of the processing device II as a whole.

The sheet processing device 11 is here a scanner of documents of the front / back type in which the processing unit 27 is a read head capable of transmitting data representative of the inscriptions carried on the sheet. These data are transmitted via an input-output port 160 connected to an interface circuit 150. The device further comprises a main data processing circuit 100 associated by a link
BUS 120 to a read only memory 170, to a random access memory 180 and to a buffer memory 140 interposed between a video processor 130 and the output input interface 150. The processor receives the data produced by the read head.

The main processing circuit 100 is also connected to a keyboard 190 by which the user can transmit the desired operating commands. The processing circuit 100 also controls the drive motor 15 of the moving element via a power and adaptation circuit 210. The motor drives the moving element 13 in rotation possibly via a system of training 225.

 The data produced by the read head are processed by the video processor 130, itself controlled by the main processing circuit 100; they are then temporarily stored in the buffer memory 140 before being transferred to the interface 150.

 The means more specific to the invention consist of the optical track 36 described above and fixed on the movable assembly 13 and by the optical detection unit 34 delivering the signal S1. This is applied to an interface circuit 240 transforming the signal S1 into digital information applied to the main processing circuit 100. The exploitation of the information delivered by the interface circuit 240 is managed by the main processing circuit 100 as a function of several specific programs written to ROM 170.

 FIG. 9 presents the algorithm of one of these programs making it possible to manage the movement of the mobile assembly from one of its processing positions to the other. This algorithm includes 11 steps, the progress of which depends on the actual state of the scanner at a given time.

 Step E10 corresponds to switching on the device.

Step E20 consists in making a comparison between the signal S1 converted by the interface 240 and a reference value corresponding to S1a and representative of the front operating position. If the signal S1 is greater than or equal to the value S1a, this means that the moving element is in the front position and the algorithm goes to step Eu 00 initializing the operations of reading the document first on the front, then in back (CONTINUED). Otherwise, the algorithm goes to step E30.

 Step E30 consists in comparing the signal S1 with a reference value corresponding to S1d and representative of the reverse operating position. If the signal S1 is less than or equal to the value S1d, this means that the moving element is in the back position and the algorithm then proceeds to step Eu 10 authorizing the operations of turning the moving element towards the position of front and then back to E20 test. Otherwise, the algorithm goes to step E40.

 Step E40 consists in developing information indicating to the system that the mobile assembly is in the intermediate position and that it is necessary to bring it back to the front operating position.

The step E50 which follows consists in controlling the rotation of the mobile assembly to bring it back to the front operating position. The stage
E60 is launched simultaneously.

 Step E60 is a test consisting in verifying that the rotation of the moving assembly takes place correctly. To do this, the main processing circuit 100 regularly reads the information delivered by the interface 240 and verifies that it corresponds to variations in the signal SI between the levels Slh and S1c. As soon as the signal S1 becomes constant, the algorithm goes to step E65. This consists in stopping the drive motor 15 of the mobile assembly 13.

 We then renew the tests E20 and E30 again leading to steps E100 and Ex 10. If the result of the test E30 is still negative, we go to step E90 which consists of the emission of an error message warning l 'user that it was not possible to bring the moving element in one or the other of the stable treatment positions.

 FIG. 10 represents another algorithm also written into read only memory 170 and which makes it possible to deal with a particular operating anomaly as illustrated in FIG. 7. Indeed, it may happen that a sheet 25 engages in the interstitial space 38 between the moving element 13 and the base 17, until it is placed between the optical detection unit 34 and the optical track 36. In this case, the signal S1 takes a constant value depending on the coefficient of leaf reflection. The algorithm for detecting such an anomaly includes 5 steps.

Step E200 is an initialization step, the variables ROT and
VAR are set to zero.

 Step E210 consists in testing whether a rotation of the moving element 13 has been requested. If so, we go to step E215, otherwise we go to step E220.

 Step E2 15 consists in setting the variable ROT to 1.

Step E220 is a test consisting in determining whether the signal S1 varies. If so, we go to step E225. Otherwise we go to step
E230.

 Step E225 consists in setting the variable VAR to 1.

Step E230 is a test consisting in verifying the state of the variables
ROT and VAR. If these variables have the same value, it means that a rotation takes place normally or that the moving equipment is fixed and that there is no variation in the signal S1. This is the normal case and the algorithm then starts again at step E210 after resetting the variables ROT and VAR to step E231. If the E230 test is negative, this means that the situation is abnormal and corresponds to a bad positioning of the sheet, in particular the case illustrated in FIG. 7. Indeed, if the E230 test is negative, it means that a rotation of the moving part is requested but the detector does not read the variations of the signal S1 or else the moving part is fixed but a variation of the signal S1 is detected.

In this case, we go to step E240 which consists in displaying an error message intended for the user and preferably in the preparation of a command to stop a drive motor. , the motor 15 in the first case or one of the motors of the access arrangement 19 or 21 concerned.

Claims (21)

 1- Device for processing sheets of the type comprising a movable assembly (13) in rotation relative to a base (17) and capable of taking several different predetermined processing positions, comprising an optical detection unit (34) and an optical track (36) arranged opposite said unit so that it can be scanned by it, characterized in that said optical track (36) has an optical property having different values over predetermined ranges thereof, certain ranges (37a, 37d) being representative of the aforementioned processing positions of said moving assembly and in that it further comprises processing and processing means (100, 240, 170) of the signals (S1) delivered by said optical detection unit (34 ), for controlling said moving part and / or detecting operating anomalies.  2- Device according to claim 1, characterized in that said optical property is reflection, adjacent areas (37 to 37d) of said track having different reflection coefficients.  3- Device according to claim 2, characterized in that said optical detection unit comprises a light source (40) and a photosensitive sensor (41) oriented to be coupled to each other by light reflection on said track (36 ).  4- Device according to claim 3, characterized in that said detection unit (34) is installed on said base (17) and in that said optical track (36) is installed on said movable assembly (13).  5- Device according to one of the preceding claims, characterized in that said movable assembly having two treatment positions, for example for a recto / verso treatment of sheets, said track comprises two extreme ranges (37a, 37d) corresponding to these two processing positions and having respectively two predetermined and different reflection coefficients (a, d).  6- Device according to claim 5, characterized in that said track comprises a series of intermediate ranges (37h, 37ç) between said extreme ranges, said intermediate ranges having at least two other predetermined and different reflection coefficients (b,), alternately succeeding on said track.  7- Device according to claim 5 or 6, characterized in that the two reflection coefficients (a, d) corresponding to the two aforementioned processing positions are a maximum reflection coefficient (a) and a minimum reflection coefficient (d).  8- Device according to all of claims 6 and 7, characterized in that said two other reflection coefficients are two different intermediate reflection coefficients (b, ç) lying in the interval defined by said minimum and maximum reflection coefficients .  9- Device according to one of claims 6 or 8, characterized in that the lengths of said intermediate ranges (37b, 37c) in the direction of relative movement between said track and said optical detection unit, vary according to a predetermined law of progression .  10- Device according to one of the preceding claims in which an interstitial functional clearance space (38) is provided at the periphery of the movable assembly between it and said base, characterized in that said optical track (36) and said optical detection unit (34) are respectively arranged on either side of this interstitial space in a location such that a sheet (25) engaged therein is interposed between said detection unit and said track.  11- Device according to one of the preceding claims, characterized in that said movable assembly houses a processing unit (27) and a guide arrangement (28) of sheet defining at least part of a processing path (30) of such a sheet, passing opposite said processing unit.  12- Device according to claim 11, characterized in that the processing unit (27) comprises a read head.  13- Device according to claim 11, characterized in that the processing unit comprises at least one printing means.  14- Device according to claim 13, characterized in that said printing means is of the thermal transfer type.  15- Device according to claim 13, characterized in that said printing means is of the ink jet type.  16- Office machine, characterized in that it comprises or is equipped with a sheet processing device (11) according to one of the preceding claims.  17- Office machine according to claim 16, characterized in that it essentially constitutes a document scanner.  18- Office machine according to claim 16, characterized in that it essentially constitutes a fax machine.  19- Office machine according to claim 16, characterized in that it essentially constitutes a printer.  20- Office machine according to one of claims 16 to 19, characterized in that said sheet processing device is equipped with means for connection to a computer.  21. A microcomputer characterized in that it comprises at least one sheet processing device according to one of claims 1 to 15.