Abstract:
The invention relates to a device for reading information stored on an information plate ( 6, 7 ) and/or writing information on an information plate ( 6, 7 ), comprising a stacking unit for the storage of at least two information plates in storage compartments ( 1, 2, 3, 4, 5 ). The invention is characterized in that the stacking unit comprises an electromechanical switching unit for detecting the information plates ( 6, 7 ) and in that the switching unit can be operated by the plate edges of the information plates ( 6, 7 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a device for reading information stored on an information plate and/or writing information on an information plate, comprising a stacking unit for the storage of at least two information plates in storage compartments. 
     Such a device is known, for example, from the document JP 8087811A. Such devices are usually called changer devices. The term information plates is understood to refer to disc-shaped information carriers, for example CDs, CD-ROMs, and DVDs. 
     The information plates are stacked one above the other in individual pigeonholes. It is necessary for a reliable operation of the changer device that the control of the device should receive information as to which pigeonholes contain an information plate. 
     Optical sensors are provided in the known device inside the stacking unit for the detection of the information plates, which sensors form a photoelectric barrier. 
     Such optical sensors tend to become unreliable in the case of pollution. In addition, the sensor function is dependent on the optical reflection or transparency properties of the information plates. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an alternative device of the kind mentioned in the opening paragraph which renders possible a reliable, failure-proof detection of the information plates inside the stacking unit. 
     According to the invention, this object is achieved in that the stacking unit comprises an electromechanical switching unit for detection of the information plates, and in that the switching unit can be operated by the plate edges of the information plates. 
     Such an electromechanical switching unit operates very reliably, shows no tendency to fail in the case of pollution, and its function is independent of the optical reflection and transparency properties of the information plates. 
     When an information plate is being transported inside the stacking unit, the electromechanical switching unit is operated by the edge of the respective passing information plate, whereby an electrical signal can be obtained from which the occupation of the individual storage compartments in the stacking unit can be concluded. 
     The inlet slopes in the embodiment of the invention as claimed in claim  2  render it possible to actuate the switching unit with a very small force. 
     The dimensioning of the slopes in accordance with claim  3  renders possible a very compact construction of the stacking unit. 
     The advantageous embodiment of the invention as defined in claim  4  renders it possible to utilize standard components, for example standard contact switches, for the switching unit. This is particularly favorable as regards cost price. 
     In the advantageous embodiment of the invention in accordance with claim  5 , the switching unit may at the same time also be utilized for ascertaining whether the information plate has fully entered the storage compartment during the process of filling the storage compartment, which is in the transitional position. Once it has fully entered the storage compartment, the information plate presses against the switching unit, from which a stop signal can be derived for switching off the transport mechanism. The switch accordingly not only has the function of detecting the occupation of the storage compartment but also a further detection function. This dual function of the switching unit implies that an additional switch can be dispensed with. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A few diagrammatically depicted embodiments of the invention will now be explained in more detail with reference to the drawing comprising FIGS. 1 to  4 , of which: 
     FIG. 1 is a perspective view of a stacking unit of a device for reading information stored on an information plate and/or writing information on an information plate, where four individual compartments are in lower stacking positions and one individual compartment in a transitional position, 
     FIG. 2 shows the stacking unit of FIG. 1, with four individual compartments in upper stacking positions and one individual compartment in a transitional position, 
     FIG. 3 is a diagrammatic lateral elevation of the device, and 
     FIG. 4 is a diagrammatic cross-sectional view of a switching unit for detecting the information plates inside the stacking unit. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a stacking unit of a device for reading information stored on an information plate and/or writing information on an information plate. The stacking unit comprises a number of individual pigeonholes  1  to  5  shaped as flat storage compartments. An information plate  7  is present in the upper compartment  1 , and an information plate  6  is present in the lower compartment  5 . The compartments  2  to  5  are all in their respective lowermost positions, i.e. moved as far down as possible. The displacement of the compartments  1  to  5  in a stacking direction  12  may take place, for example, through rotation of worm gears whose outer threads are in engagement with recesses  13 ,  14 , and  15  of the respective compartments. The compartment  1  is in a transitional position from which a transport of the information plate  7  is possible by means of a transport mechanism which is not shown in any detail, i.e. into a playback position for playing the information plate or into an ejection position for removing the information plate from the device. The various compartments are transported in the stacking direction  12  into the transitional position for the purpose of loading and unloading. Preferably, the slope of the worm gears (not shown) in the region of the transitional position is greater than in the region of the stacking positions, with the result that the distance H between the individual compartments changes during the process of displacement inside the stacking unit. A detailed description of the operation of such a stacking unit is described in the document EP 0892403, which is to be included through express reference into the disclosure of the present application. 
     The distance H is at its greatest in the transitional position, in which the compartment  1  is present. This creates room for the transport mechanism, which is not shown in any detail, for transporting the information plate  7  from the transitional position into an ejection or playback position. By contrast, the distance between the individual compartments is very small in the lower stack positions in which in FIG. 1 the compartments  2  to  5  are present. A switching unit with an electrical switch  10 , an operating lever  11 , and an abutment element  9  are arranged in the peripheral region of the information plate  7 . The operating lever  11  is rotatably journaled and comprises inlet slopes  11   b  and  11   c  as well as an extension  11   d . The extension  11   d  lies against a switching lever  10   a  of the electrical switch  10 . 
     When an information plate is moved up or down inside the stacking unit in the stacking direction  12 , its outer edges slide along the inlet slopes  11   b / 11   c  of the operating lever  11 , whereby the operating lever  11  is pivoted in the direction of the switch  10 . The extension  11   d  thus presses against the switching lever  10   a  of the switch  10 , whereby the switch  10  is operated. The switching point of the switch  10  is chosen such that it is switched the moment the relevant information plate lies approximately at the level of point  11   a  of the operating lever  11 . This is true for the information plate  7  in FIG.  1 . 
     The switch  10  supplies a switching signal to a control unit of the device which is not shown in any detail. In combination with an unequivocal assignment signal for that individual compartment which is instantaneously in the transitional position, which signal is not described in any detail here, it can thus be unequivocally detected through a simple displacement of the individual compartments inside the stacking unit which individual compartments are provided with an information plate. This is stored in an electric memory. 
     To fill an individual compartment with an information plate, the relevant compartment is to be transported into the transitional position, in which in FIG. 1 the compartment  1  is present. The information plate to be inserted can now be transported by means of the transport mechanism, which is not shown, from an ejection or playback position into the compartment present in the transitional position. During this, the edge of the information plate operates the lever  11  in point  11   a  and thus switches the switch  10 , from which a stop signal for controlling the transport mechanism can be derived. The switch  10  thus has a dual function. 
     FIG. 2 shows the stacking unit of FIG. 1 with the compartments  1  to  4  being moved into the upper stack positions and the compartment  5  with the information plate  6  being in the transitional position. In the situation shown in FIG. 2, the switch  10  is just being switched by the information plate  6 . The individual compartments  2 ,  3 , and  4  have indeed passed the point  11   a  of the contact lever on their way upwards from the lower stack positions into the upper stack positions, but the switch  10  was not operated thereby because the compartments  2 ,  3 , and  4  are not filled with information plates. 
     FIG. 3 is a diagrammatic side elevation of a device  20  for reading information stored on an information plate and/or writing information on an information plate. To clarify the manner of operation, an information plate  20  is shown in various positions  20   a  to  20   k  inside the device. The position  20   a  represents an ejection position in which the information plate can be taken from the device  20 . The information plate can be transported from the ejection position  20   a  into a playback position  20   b  on a turntable  21  by a transport mechanism, which is not shown in any detail, or into a transitional position  20   c  inside the stacking unit  22 . The fact that a plate has reached the transitional position is detected by means of the switch  10  and the operating lever  11  in that the plate edge of the information plate  20   c  presses against the tip  11   a  of the operating lever. This switches off the transport mechanism which is in charge of the transport between the ejection/playback position and the transitional position. Starting from this transitional position, the information plate can now be transported into upper stack positions  20   d  to  20   g  or lower stack positions  20   h  to  20   k  by means of a further transport mechanism, in particular the worm gear mechanism described with reference to FIG.  1 . 
     FIG. 4 is a diagrammatic cross-sectional view of the switch  10  and the operating lever  11  of FIGS. 1 to  3 . The operating lever  11  is rotatably journaled about a pivot axis  23 . When an information plate moving down inside the stacking unit presses from above against the inlet slope  11   b , or moving up presses from below against the inlet slope  11   c , the operating lever  11  will pivot in the direction of the arrow  24 . The extension  11   d  then presses against the switching lever  10   a  of the switch  10 , whereby a switch contact is established with the contact surface  10   c  and a control signal is supplied to a control unit which is not shown in any detail.