Abstract:
A portable printer is provided which provides active cooperation between a computer and the portable printer unit. A number of different features are introduced into the printing unit which allow greater responsiveness from the computer responsive to actions taken at the printer unit.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a printing system and to a printer unit for use in such a system.  
         BACKGROUND TO THE INVENTION  
         [0002]    In the state of the art, a number of printers arranged to be manually placed on an image receiving medium are known. The printing means of the printer or the entire printer is operable to scan over the image receiving medium in the printing operation. Thus, the medium is not fed through the printer—as in most office sheet printers, but the printer is placed upon the medium.  
           [0003]    Such a printer is known from EP 564297-A. The printer has an ink jet print head which is scanning in two orthogonal directions over the image receiving medium, onto which the printer is placed manually. The printer is connected to a computer and capable e.g. of printing addresses onto envelopes, but can also be used separately from the computer for printing data downloaded from the computer to the printer.  
           [0004]    Another ink jet printer to be placed on a printing medium is disclosed in U.S. Pat. No. 5,634,730 A. This printer is provided with a keyboard for data inputting, but can also print images downloaded from a computer. The print head scans over the image receiving medium along a special path, e.g. helically or like a pendulum. It can print data downloaded from a computer or one of a set of predetermined words such as “PAID” etc.  
           [0005]    DE 3142937-A refers to a so-called hand stamp which is placed manually on the image receiving medium. It can print data downloaded from an accounting machine, or images consisting of user-selected fixed phrases. The hand stamp has a thermal print head and an ink ribbon for printing.  
           [0006]    The printers known in the prior art are thus capable of printing an image onto an image receiving medium, and make use of a scanning print head. Printing is performed in two steps: the first one is alignment of the printer on the image receiving medium such that the image can be printed in the desired position and the second step is printing. However, although the printers can communicate with a computer to receive data to be printed, that is the limit of their interaction. There is no other active cooperation between the printer unit and a computer.  
         SUMMARY OF THE INVENTION  
         [0007]    It is one aim of the present invention to provide a printing system in which there is more active cooperation between a computer and the printer unit.  
           [0008]    According to one aspect of the invention there is provided a printing system comprising:  
           [0009]    a printing unit;  
           [0010]    a base station configured to receive the printing unit when not in use and having means for detecting movement of the printing unit from the base station;  
           [0011]    a computer connected to the base station and configured to execute a printing application for generation of printing data for the printing unit,  
           [0012]    wherein said printing application is initiated by the computer when movement of the printing unit from the base station is detected.  
           [0013]    Another aim of the invention is to provide a printer unit for use in a printing system which has a wider range of user interface functions.  
           [0014]    According to another aspect of the invention there is provided a printing system comprising:  
           [0015]    a printing unit; and  
           [0016]    a computer connectable to the printing device and configured to execute a printing application for generation of printing data for transmission to said printing device for printing;  
           [0017]    wherein the printing system includes a memory which holds a plurality of default printing data options each having associated therewith a time activation period and means for determining the time at which the printing application is initiated, wherein the printing application includes a default output sequence for generating one of said default printing data options in accordance with the detected time of initiation of the printing application.  
           [0018]    This allows a user profile to be recognised so that the printing system is responsive to a user&#39;s requirements. The memory may be in the computer or within the printing unit.  
           [0019]    A further aspect of the present invention provides a printer adapted for communication with a host computer, the printer comprising:  
           [0020]    communication means for receiving printing data to be printed from the host computer while a communication link exists between the printer and the host computer, said printing data defining a sequence of images to be printed;  
           [0021]    a data path for conveying data received at the communication means to a printing mechanism for printing said data;  
           [0022]    a user input means for instigating a print command; and  
           [0023]    a controller connected to the printing mechanism and operable to allow the printing mechanism to print successive images in the sequence, each successive image being printed responsive to the user instigated print command.  
           [0024]    This feature can be used with the printer connected to the computer and for receiving successive images therefrom, or at a location remote from the host computer when the communication link is broken. In that case, the printer can have a store for holding the printing data.  
           [0025]    In addition, this aspect of the invention provides a method of printing a series of images comprising:  
           [0026]    establishing a communication link between a printer and a host computer;  
           [0027]    transferring printing data defining said images from the host computer to the printer;  
           [0028]    breaking the communication link and moving the printer unit to a location remote from the host computer; and  
           [0029]    at the remote location, printing successively each image in the sequence responsive to a user instigated print command at the printer unit at said remote location.  
           [0030]    According to an alternative aspect of the present invention, there is provided a method of printing a series of images comprising:  
           [0031]    establishing a communication link between a printer and a host computer, the printer including user input means for instigating a print command; and  
           [0032]    successively transferring printing data defining each image in the sequence from the host computer to the printer and printing said each image responsive to a user instigated print command.  
           [0033]    Another aspect of the invention provides a printing system comprising:  
           [0034]    a printing unit including user input means for instigating a print command;  
           [0035]    a base station configured to receive the printing unit when not in use;  
           [0036]    a computer connected to the base station and configured to execute a printing application for generation of printing data for the printing unit, the computer comprising a keyboard; and  
           [0037]    wherein execution of the printing application is interrupted by operation of any key on the keyboard of the computer or the user input means on the printing unit.  
           [0038]    One key of the keyboard may be defined as a “hot key” which remains active as the application is running such that when the hot key is depressed, a particular function is initiated.  
           [0039]    For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made to the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0040]    [0040]FIG. 1 is a plan view showing a printer, a base station and a computer;  
         [0041]    [0041]FIG. 2 is a view of the printing mechanism of the printer;  
         [0042]    [0042]FIG. 3 is a view of a printer in use;  
         [0043]    [0043]FIG. 4 is a flow diagram of the software printing application;  
         [0044]    [0044]FIG. 5 is a block diagram illustrating time related activation default options; and  
         [0045]    [0045]FIG. 6 illustrates a sequence of images to be printed.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0046]    [0046]FIG. 1 shows a printing system consisting of a computer  10 , a computer controlled display  12 , which is in the described embodiment of the invention a CRT, a keyboard  14  linked to the computer  10  by means of a cable  16 , another cable  18 , connecting the computer  10  with a base station  20 , which is connected to a printer  24  by means of a cable  22 . Thus, the printer  24  is linked to the computer via the cables  18 , 22  and the base station  20 .  
         [0047]    As known in the prior art, the computer  10  comprises a processor on which a software is running, comprising an operating system, a printer driver to enable printing with the printer  24  from the operating system and a software application by which data can be created, selected and formatted on the PC, for defining image patterns to be printed by the printer  24 . The software application can be activated in a number of ways:  
         [0048]    selected by the user at start-up or from the desktop: the user places the software application in the start-up directory or creates an icon on the desktop;  
         [0049]    from within another application: the user invokes the software application from a button (displayed on the display  12 ) in the toolbar of another software application or from its own floating toolbar.  
         [0050]    from the handheld printer  24  itself: if the application is not running, the user presses a print button  34  on the handheld printer  24 , which will automatically invoke the software application in the first instance.  
         [0051]    According to an embodiment of the invention, however, the software application is activated on the computer  10  for controlling the printer  24  by lifting the printer  24  off the base station  20 . A switch  32  is provided in the base station  24  sensing the presence or absence of the printer  24  by means of a pin  30 . When the printer  24  is placed upon the base station, the pin  30  is depressed, and the switch  32  is closed. In the case that the printer  24  is removed from the base station  20 , the pin  30  which is biased in the vertical direction moves upwardly and the switch  32  opens. The switch is connected via some electronic circuits to the computer  18  and activates the software application for printing. Conversely, when the printer  24  is returned to the base station, the state of the switch is detected to automatically return the computer to the main application which it was executing when the printer was removed. This functionality is described in more detail later with reference to FIG. 4.  
         [0052]    That is, a default printing application on the computer changes to the present printing application when it is “activated” by one of the techniques mentioned. When it is “deactivated”, the default printing application is returned to an original printing application.  
         [0053]    The base station  20  is connected to the computer  10  by means of the cable  18 , which can be a parallel or a USB cable. Electric power is supplied to the base station  20  by a separate mains transformer, but could also be supplied from the computer via the cable  18 , preferably when the cable  18  is a USB cable. The cable  18  can be hard-wired to the base station  20 , or connected to a socket of the base station, which is preferably provided at the rear thereof. When the printer  24  is not in use, the handheld printer will be placed in the base station  20 . The base station  20  will ensure that the ink jet print head of the printer  24  is protected when not in use by a capping device that will be automatically triggered whenever the printer is inserted into the base station  20 . The base station  20  will also cause the print head of the printer  24  to eject ink into a reservoir and mechanically clean the surface of the print head. These measures are necessary to maintain optimum print quality.  
         [0054]    The umbilical cable  22  connects the base station  20  to the hand held printer  24 , providing both power and data. A LED on the printer will indicate that power is on. The printer  24  is removed from the base station  24  and positioned on the surface to be printed. The length of the cable  22  limits the distance of travel from the base station.  
         [0055]    In another embodiment of the invention, the printer is arranged to be disconnected from the base station by unplugging the umbilical cable  22  and moved to another location wherein printing of the contents of on-board memory, i.e. downloaded image data, can be effected. The user will employ scroll buttons on the printer to select the required print data, which appear in a small LCD. Once a selection has been made, pressing the print button  34  will activate printing. Having selected the data to print using the software application (or the scroll buttons on the printer), the user will activate printing from the print button  34  on the hand held printer  24  itself.  
         [0056]    According to a further alternative, data for printing can be sent to the printer using RF or IR technology. The scroll buttons may be used to select data which may be stored on the “smart card” or which resides in the computer.  
         [0057]    Print alignment is achieved visually through a transparent window  36  in the print casing. This window  36  can also be opened for inserting an ink cartridge into the printer  24  before use. The cartridge is then clamped in a carriage of the printer  24 . The window  36  must be closed before printing; thus there is a switch provided in the housing of the printer for detecting whether the window is closed or not. When the window  36  is not closed, the switch disables printing. Changing a cartridge is achieved by lifting a retaining lever and extracting the cartridge in use and replacing this with a new or different colour cartridge in the way described above. If the removed cartridge still contains ink and is to be reused it must be capped to avoid the ink drying out.  
         [0058]    Alternatively a Think jet type head from Hewlett Packard may be used which utilises a different type of ink which does not dry out in the print head.  
         [0059]    The printer  24  contains a print mechanism with the ink jet print head having a number of print nozzles, and an ink supply. The print head is moved by means of motor driven scanning means within the housing in two (generally orthogonal) directions such that a rectangular area can be imprinted through an aperture of the printer  24  at the bottom of its housing. Thus, the printer  24  is placed manually on an image receiving medium and—when the print button  34  is depressed—the print head scans over the medium and imprints it by spitting ink droplets onto it.  
         [0060]    [0060]FIG. 1 shows the presence of a “Smart Card” reader  28  in the base station  20 . Smart cards  26 , i.e. memory cards, may be used for storing data or images or as a substitute for additional RAM in the base station.  
         [0061]    In another embodiment, a printer is provided which can only be used as a standalone device, i.e. in cooperation with a base station. The functionality of the printer is then as follows: the user removes the printer from the base station. A single button  36  (see FIG. 2) will switch the printer on and off, and a LED on the printer will indicate that power is on. A ROM card containing the selected image data is inserted into the printer. The ROM card is printed with images of its content and the sequence of images provided on the ROM card is indicated numerically on a display of the printer. Thus, the user will select the desired image using scroll buttons to scroll forward or backwards through the numbered content. The user will activate printing from the button  36  on the handheld printer itself.  
         [0062]    The print mechanism of the printer will now be described with reference to FIG. 2. The printer  24  has a housing, the underside of which can be abutted against the surface of the image receiving medium to be printed. A print face  11  is defined by the scanning range of an ink jet print head cartridge  126  which can be replaced using the cartridge release mechanism described above. The ink jet print head cartridge  126  is mounted for movement along a write axis  128  by virtue of a cooperating lead screw  130  and nut  132 . The movement is controlled by a stepper motor  134 . The position of the writing axis  128  can be altered by an indexing axis lead screw and bush  136  controlled by a further stepper motor  138 . Reference numeral  140  designates a stability bar which extends parallel to the write axis  128 , the ink jet print head cartridge  126  being mounted between the write axis  128  and the stability bar  140 . Reference numeral  142  designates an indexing axis stability bar and bush.  
         [0063]    The printer also includes an electronic controller  100  having a microprocessor for controlling movement of the stepper motor  34  and generating signals for controlling the print head and having a buffer memory for storing data. The microprocessor is capable of converting data from a computer to which the device is connected into a format suitable for driving the print head. The buffer memory can store information in a variety of formats to enable the printer to work with a variety of computer equipment.  
         [0064]    If a Think jet print head is used, a DC motor and encoder may be used in place of a stepper motor.  
         [0065]    In FIG. 3, a printer  24  positioned on an image receiving medium  40  is shown ready for use. That is, it has been removed from the base station  20  and placed on the medium  40  to be printed. In doing so, the application software is automatically initiated to allow printing data to be selected and configured by a user using the computer  12  and keyboard  14 .  
         [0066]    Some aspects of the application software will now be described with reference to FIGS.  4  to  6 . In addition to the automatic initiation of the application, the application allows for a number of default print options depending on a user profile as will now be described. FIG. 4 is a flow chart of the printing application. Assume the computer is executing a main application (step SO) and the printer  24  stands ready for use on the base station  20 . At step S 1 , the state of the switch is monitored by the application software to determine whether or not the printer unit  24  is on the base station  20 . When the printer unit  24  is removed from the base station  20 , at step S 2  the printing application is initiated by the computer. At step S 3 , the printing application determines whether or not default options are set. If no default options are set, a number of print options are displayed on the PC display at step S 4  from which a user may select his required option at step S 5 . Alternatively, a user may simply use the printing application initiated at step S 2  to create, select and format printing data using the keyboard  14  and the display  12  as with any existing printing application. However, the provision of default options simplifies use of the printing system for a user, in particular a user who has predictable requirements.  
         [0067]    If default options are found to be set at step S 3 , the application software selects one of the default options based on the time of use, as indicated at step S 6 . This is described in more detail later. At step S 7 , print data is generated in accordance either with the user selected option at step S 5  or the default option selected by the application software at S 6 . Then, at step S 8  the printing data is transmitted to the printer  24  ready for printing.  
         [0068]    Step S 1  is periodically implemented to check the status of the printer  24 . If it is determined to have been returned to the base station, the computer automatically returns to the main application, step S 0 .  
         [0069]    [0069]FIG. 5 is a block diagram illustrating elements of the system to implement default options with time related activation periods. A default control block  50  selects from a plurality of default options held in a memory  52 . The selected option is used by a default output sequence  54  to generate default printing data for the printer unit  24 . Default control block  50  can be responsive to an internal clock  56  or diary function  58  of the computer system so that a default options is selected in accordance with the time of day or day of the week. Alternatively, the default options may be supplied to the display  12  where a user selects a particular option, for example using user activated icons.  
         [0070]    For example, for options with a time related activation period, a user could set the default output to be “RECEIVED” when the internal clock  56  of the computer indicates the time between 9 am and 11 am, and from 11.01 am and 5.30 pm the default output could be an address format.  
         [0071]    During printing, the system may be interrupted at any stage by pressing any key on the keyboard  14  or any button on the printer unit  24  itself, in particular the print command button  34 .  
         [0072]    One of the advantages of the system described herein is that the printer unit may be used at locations remote from the computer. In particular, this is the case where the cable  22  which normally connected the printer unit  24  to the base station  20  can be detached. It may be the case that it is desired to print sequential information at a number of different remote locations, for example so as to print on a number of different products. FIG. 6 illustrates a sequence of images denoted  11 ,  12 ,  13  each of which carry a common part  60  of information and a sequentially varying part  62 , that is the numbers 1, 2, 3. The system described herein allows the whole sequence of images to be transmitted to the printer unit during operation of the application software (step S 8  in FIG. 4). Subsequently, each image in the sequence can be individually printed responsive to operation of the print command button  34  on the printer unit  24 . After an image in the sequence has been printed, the controller in the printer automatically selects the next image for printing on the next print command. This technique is useful for example in printing sequential numbers as illustrated in FIG. 6, barcodes or a sequence of database information.  
         [0073]    [0073]FIG. 3 illustrates the printer in use to print a sequence of images. The first image,  11 , has been printed by the printer  24 . The printer  24  has been lifted up and relocated in a different position. On actuation of the print command button  34 , the next image,  12 , in the sequence will be printed at the new printer location.