EP0787586A1

EP0787586A1 - Printing device and postage franking machine

Info

Publication number: EP0787586A1
Application number: EP95934841A
Authority: EP
Inventors: Nobuchika Menda; Yasushi Kawamoto; Masakazu Suzuki; Masahiro Seguchi; Naoyuki Wakabayashi; Katsuhiko Ohta
Original assignee: Omron Corp; Omron Tateisi Electronics Co
Current assignee: Omron Corp
Priority date: 1994-10-20
Filing date: 1995-10-19
Publication date: 1997-08-06
Also published as: EP0787586A4; WO1996012621A1

Abstract

A printing medium conveyed relative to a printing head is subjected to printing on a printing device. The printing head is arranged on a side of a conveying surface of a conveying passage for the printing medium along which the printing medium is conveyed. The conveying passage for the printing medium is inclined in a widthwise direction of conveyance, and a lower edge of the inclined conveying passage surface is bent in a V-shape along a direction of conveyance to provide a V-shaped conveying surface. The printing head is arranged in the vicinity of the V-shaped bent portion of the V-shaped conveying surface.

Description

TECHNICAL FIELD

The present invention relates to a printing device for printing on mail or other printing media. More specifically, the invention relates to a printing device and postage franking machine which performs a stable printing process irrespectively of the size or softness of the printing media. Furthermore, the invention relates to a printing device and postage franking machine for printing at proper places of such a printing medium as envelopes and other postal matters having a cellophane transparent window.

BACKGROUND ART

Generally, the printing device for printing on printing media that are continuously transferred are known as the following systems:

1. A system that a previously printed seal-like label is stuck onto a printing medium;
2. A system that a print roller is pressed directly against the surface of a printing medium; and
3. A system that ink is jetted out for printing with an ink jet type print head.

However, in these printing devices, different sizes of printing media would give rise to a need of position adjusting equipment or pressing-force adjustment equipment for coping with the size of the printing medium. As a result, miniaturization and reduction in cost have been impossible for those printing devices. Moreover, in the case of soft printing media, it has been difficult to print on the surface thereof.
In any of these printing devices, the print position is fixed with respect to a regular position of printing media such as postal matters, the printing is effected at this regular print position. As a result, the devices have had a problem as described below.
That is, as shown in Fig. 19, in the case of an envelope 200 having a cellophane transparent window 201, when the printing is executed at a regular position by the aforementioned printing device, a printed-image range 202 may overlap the transparent window 201, such that the printed image of an overlapping portion 203 (hatched for convenience of drawing) would be dimmed and erased, disadvantageously.
Further, in the case where a step gap is formed in the envelope 200 by a content 204 enclosed inside the envelope 200, as shown in Figs. 20 and 21, when the printing is executed at the regular position by the printing device, a lack 205 may occur to a portion of the printed image corresponding to the step gap. This would lead to a problem that important portions of the printed image for mail service such as the charging amount (postage) and date are omitted.

DISCLOSURE OF THE INVENTION

A first object of the present invention is to provide a printing device and postage franking machine which is capable of achieving a stable printing irrespectively of changes in size or softness of the printing media, based on the fact that disposing the print head on the conveyance-surface side makes it possible to maintain the opposing distance between print head and printing medium.
A second object of the present invention is to provide a printing device and postage franking machine which is capable of obtaining a clear printed image by controlling the printing medium or the print head to effect the printing at a proper printing place so that any disappearance or omission of the printed image can be prevented securely.
According to a first aspect of the invention for achieving the first object, there is provided a printing device for printing on a printing medium conveyed relatively to a print head, the print head being disposed on a conveyance-surface side of a printing-medium conveyance path for conveying the printing medium.
In this aspect of the invention, when the printing medium is conveyed along the printing-medium conveyance path, the print head disposed on the conveyance-surface side effects printing from lower conveyance-surface side to upper printing medium on a lower surface of the printing medium. Accordingly, for printing onto the printing medium, the opposing distance between the bottom surface of the conveyed printing medium and the print head opposing thereto from below can be maintained constant at all times regardless of the size or softness of the printing medium. Thus, the print head no longer needs to be adjusted for farness or nearness in position, so that the device can be designed for smaller size or lower cost. Moreover, the device can yield a beautiful, high-grade printed image suitable for continuous printing.
According to a preferred embodiment of the first aspect of the invention, the device further comprises a V-shaped conveyance surface which is bent into a V shape along a conveyance direction over a lower edge portion of a tilted conveyance surface tilted widthwise of the printing-medium conveyance path. With this arrangement, the printing medium of, for example, an oblong shape introduced onto the V-shaped conveyance surface formed into a V shape along the conveyance direction is supported at its bottom surface and one side surface thereof by the tilted both surfaces in the V shape, so that the printing medium is conveyed in such a stable state that any widthwise shifts of the printing medium is restricted.
According to another preferred embodiment of the first aspect of the invention, the print head is disposed at a place near the V-shaped bent portion of the V-shaped conveyance surface. With this arrangement, the printing medium is conveyed by referencing the V position, making it possible to print at a regular set position located at a specified length from an end of the printing medium, after achieving a positioning thereto.
According to yet another preferred embodiment of the first aspect of the invention, the print head is implemented by an ink jet type print head. With this arrangement, the print head will make no contact with the printing medium, eliminating the need of pressing force adjustment, so that the device can print on soft printing media securely.
According to still another embodiment of the first aspect of the invention, any of the devices as described above is incorporated into a postage franking machine to print postal matters. With this arrangement, the device is enabled to print also on postal matters of different sizes or different softnesses such as letters and parcels, securely at regular positions thereof.
According to a second aspect of the invention for achieving the second object, there is provided a printing device having a print head for performing a specified printing on a printing medium, the printing device comprising: detection means for detecting a proper printing place of the printing medium; and control means for controlling the printing medium or the print head so that printing is performed at the proper printing place detected by the detection means.
In this second aspect of the invention, in the process of carrying out a specified printing on the printing medium by the print head, the detection means detects a proper printing place (in terms of both material and flatness for proper printing) of the printing medium, and the control means controls the printing medium or the print head so that printing is performed at the proper printing place detected by the detection means. As a result, the device has an effect that it is capable of obtaining a clear printed image by securely preventing any disappearance or omission of the printed image.
According to the preferred embodiment in the second embodiment of the invention, the detection means is a material detecting means for detecting a material portion of the printing medium proper for printing. With this arrangement, since a material portion proper for printing in the printing medium is detected by the material detecting means, the device has an effect that printing can be effected by selecting a material portion that allows a clear printed image to be yielded and that has been detected by the material detecting means.
According to still another preferred embodiment of the second aspect of the invention, the detection means is a flatness detecting means for detecting a flat portion of the printing medium proper for printing. With this arrangement, since a flat portion proper for printing in the printing medium is detected by the flatness detecting means, the device has an effect that printing can be effected by selecting a flat portion, or non-step-gapped portion, that allows a clear printed image to be yielded and that has been detected by the flatness detecting means.
According to still another preferred embodiment of the second aspect of the invention, the control means has lateral moving means for moving the printing medium or the print head in parallel with the conveyance surface of the printing medium. With this arrangement, since the moving means moves the printing medium or the print head so that printing is effected at a proper printing place, the device has an effect that a clear printed image can be ensured with the print head.
According to still another preferred embodiment of the second aspect of the invention, the control means has vertical moving means for moving the print head vertically to the conveyance surface of the printing medium. With this arrangement, since the vertical moving means moves the print head vertically to the conveyance surface of the printing medium, the device has an effect that a proper printed image can be obtained by controlling the vertical position of the print head responsive to the thickness of the printing medium.
According to still another preferred embodiment of the second aspect of the invention, the flatness detecting means has a touch roller that makes rolling contact with the printing medium to detect any shift in the vertical direction with respect to a conveyance surface of the touch roller. With this arrangement, since the flatness detecting means has the touch roller, a flat portion including no step gaps of the printing medium can be detected based on the touch roller by putting the touch roller into rolling contact with the printing medium. As a result, the device has an effect that a further clearer printing can be achieved.
According to still another preferred embodiment of the second aspect of the invention, the print head is implemented by a non-contact type print head. With this arrangement, since even a printing medium having some step gaps of thicknesses can be printed from a separate location away from the printing medium, the device has an effect that a clear printed image can be obtained.
According to still another preferred embodiment of the second aspect of the invention, a postage franking machine is equipped with any one of the devices as described above. With this arrangement, there can be produced an effect that postal printed information (specified prints) such as postal charges, dates and others necessary for postal matters can be printed clearly with preventions of any disappearance or omission of printed images.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a partly broken perspective view showing a postage franking machine equipped with a printing device according to a first embodiment of the present invention;
Fig. 2 is a longitudinal sectional view in the conveyance direction showing a placement state of the print head of the printing device of Fig. 1;
Fig. 3 is a longitudinal sectional view in the widthwise direction showing a printing state of each postal matter at the V-shaped conveyance surface of the printing device of Fig. 1;
Fig. 4 is an appearance perspective view of each postal matter showing printing results by the printing device of Fig. 1;
Fig. 5 is a control circuit block diagram of the postage franking machine of Fig. 1;
Fig. 6 is a flow chart showing the processing operations of the postage franking machine of Fig. 1;
Fig. 7 is an appearance perspective view of a postage franking machine equipped with a printing device according to the second embodiment of the present invention;
Fig. 8 is an explanatory view showing the internal construction of the main part in the printing device of Fig. 7;
Fig. 9 is a waveform diagram showing the relationship between the amount of light by the photodetector and the detection pulse in the printing device of Fig. 8;
Fig. 10 is an arrangement view of the flatness detecting means of the printing device of Fig. 8;
Fig. 11 is a characteristic view showing the relation of pressure-sensor detection pressure to upward and downward shifts of the touch roller in the printing device of Fig. 8;
Fig. 12 is a perspective view showing the arrangement of the print-head lifting device in the printing device of Fig. 8;
Fig. 13 is a control circuit block diagram of the printing device of Fig. 8;
Fig. 14 is a flow chart showing the printing control process of the printing device of Fig. 8;
Fig. 15 is an explanatory view of a postal matter to be printed by the printing device of Fig. 8;
Fig. 16 is a time chart showing the printing control process by the printing device of Fig. 8;
Fig. 17 is an explanatory view similar to Fig. 8, showing a modification example of the printing device according to the present invention;
Fig. 18 is a flow chart showing the printing control process by the printing device of Fig. 17;
Fig. 19 is an explanatory view showing a state in which the printed image and the transparent window are overlapping with each other in a postal matter printed by a conventional printing device;
Fig. 20 is an explanatory view showing a partly lost state of the printed image printed by the conventional printing device; and
Fig. 21 is a cross sectional view taken along the line 21 - 21 of Fig. 20.

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment

A first embodiment of the present invention is now described in detail with reference to the accompanying drawings.
Fig. 1 shows a postage franking machine 11 used for mail service. This postage franking machine 11 is so constructed that a V-shaped conveyor body 13 is overlaid on a meter body 12 located on the lower side. The lower-side meter body 12 comprises a liquid crystal display (LCD) 14 serving also for touch input, and an ID card insertion hole 15. The upper-side V-shaped conveyor body 13 comprises a meter 16, a postal-matter detection sensor S, a print head 17 of ink jet type, and a conveyor belt 18. Thus, the postage franking machine 11 automatically performs postage reckoning and postal stamping on various types of postal matters 19 of different sizes such as letters and parcels.
The LCD 14 displays charges responsive to the weight of the postal matter 19 as well as the type of treatment such as surface mail, express mail, registered mail and domestic/foreign mail. Moreover, the LCD 14 allows touch input of stamping start or the like. The ID card insertion hole 15 allows the ID card of a user to be inserted thereinto for the identification and confirmation of the user's own data, by which the postage franking machine 11 permits the user to handle it.
The V-shaped conveyor body 13 is formed into a V shape by a combination of shorter and longer components suitable for placement and conveyance of the postal matter 19 which is rectangular shaped. Besides, the V-shaped conveyor body 13 is divided into front and rear two divisions in the conveyance direction. The divisional front side is provided as a receiving tray 16a of the meter 16, and further has a weighing instrument connected thereto to measure the weight of the postal matter 19 placed on the receiving tray 16a. Also, the divisional rear side is fixed onto the meter body 12, where the postal-matter detection sensor S and the print head 17 are disposed along the conveyance direction so as to be located lower than the conveyance surface of the longer component.
In this case, as shown in Fig. 2, the postal-matter detection sensor S and the print head 17 photo-electrically detect and print the postal matter 19 from below a V-shaped conveyance surface 22 via a detection hole 20 and a print hole 21 opened near the V-shaped bent portion of the conveyor body 13.
For this process, since the print head 17 is disposed at a location lower than the V-shaped conveyance surface 22, the opposing distance between the bottom surface of the conveyed postal matter 19 and the print head 17 opposing thereto upward from below can be maintained constant at all times regardless of the size of the postal matters 19 ···. Therefore, the print head 17 no longer needs to be adjusted in the farness or nearness of position.
With the provision of the print head 17 at a location near the V-shaped bent portion, the V position serves as a conveyance reference position for the postal matter 19, so that each postal stamp 23 ··· can be positioned and printed at a regular set position of a generally fixed length from an end of each postal matter 19 ···, as shown in Fig. 4. Also, using an ink jet type print head eliminates the need for the adjustment of pressing force as a result of non-contact printing, so that a reliable printing can be achieved even on soft postal matters.
Further, by virtue of the V-shaped conveyance surface, rectangular postal matters such as letters and parcels will be conveyed stably in a two-side supported state that the bottom surface and one side surface thereof are supported by inclined two surfaces of the V shape and thereby restricted in widthwise shifts.
Further, the conveyor belt 18 that can convey postal matters placed thereon is disposed along the longitudinal direction of the V-shaped conveyance surface 22. The postal matter 19, as placed on the conveyor belt 18, will be conveyed from the preceding-stage meter 16 side to the succeeding-stage printing side.
Although the two components of the V shape have been formed into a V shape by combining shorter and longer components in the drawings, it is also possible to set the two components into any arbitrary V shape suitable for the conveyance of postal matters depending on the state of combination with the conveyor belt 18.
Fig. 5 shows a control circuit block diagram of the postage franking machine 11. This control circuit controls: a control unit 51 for controlling the circuit devices of the whole system; an external memory 52 for storing postage data and use data; a transmitter 53 for performing data communication between a host system and an external memory; an ID card reader 54 for reading data of the ID card; a display section 55 for displaying and guiding input operation and the like for the user, as well as an operating section 56 for allowing various types of input operations such as selecting a mail treatment process, both of the display section 55 and the operating section 56 being equipped in the LCD 14; a meter 16 for metering the weight of postal matters; an ink jet type print head 17 for printing images on postal matters in a non-contact manner with ink jet; a postal-matter detection sensor S for measuring print-operation timing; and a conveyor belt 18 for conveying the postal matter 19.
In use of the postage franking machine 11 constructed as described above, its processing operation is explained with reference to the flow chart of Fig. 6.
Now assuming that a user who handles this postage franking machine 11 has inserted the ID card into the ID card insertion hole 15 in compliance with the display guidance displayed on the LCD 14 (steps n1 to n2), the validity of the inserted ID card is read by the ID card reader 54 (steps n3 to n4). The control unit 51, deciding that the user is the very person of handling from the validity of the card, stands by until the postal matter 19 is placed on the receiving tray 16a (step n5). With the postal matter 19 placed on the receiving tray 16a, the control unit 51 measures the weight of the postal matter with the meter 16, and renders a selection among mail treatment process such as surface mail, express mail, registered mail and domestic/foreign mail (steps n6 to n7). When the user has selected and specified one from among these treatment processes, the control unit 51 automatically reckons the postal charge based on these data, making a display on the LCD 14 (step n8).
Subsequently, as the user enters and specifies the printing operation according to the display guidance displayed on the LCD 14, the conveyor belt 18 is driven to convey the postal matter 19. Then, as the postal matter 19 has been conveyed to pass the position of the postal-matter detection sensor S (steps n9 to n10), the print head 17 starts the printing operation for the postal stamp 23 after a certain time elapse based on the then resulting detection signal (step n11).
After the completion of printing, with the postal stamp 23 on the postal matter 19 ended, an automatic subtracting process from the user's registered account is done, and the stamped postal matter 19 is further conveyed so as to be led to the succeeding-stage next-processing side. Thus, the control unit 51 makes ready for the stamping of the next postal matter (steps n12 to n13).
As described above, in the printing onto postal matters, since the opposing distance between the bottom surface of the conveyed postal matter and the print head opposing thereto from below can be maintained constant at all times regardless of the size of the postal matters, the print head no longer needs to be adjusted for farness or nearness in position, so that the device can be designed for smaller size or lower cost. Moreover, the device can yield a beautiful, high-grade printed image suitable for continuous printing. Further, by virtue of the V-shaped conveyance surface, the postal matter can be conveyed stably in a two-side supported state. Besides, with the provision of the print head at a location near the V-shaped bent portion, the V position can serve as a conveyance reference position for the postal matter, so that the postal matter can be positioned and printed at a regular set position of a fixed length from an end of the postal matter. Also, by a combinational use of an ink jet type print head that allows non-contact printing, the need for the adjustment of pressing force can be eliminated so that a reliable printing can be achieved even on soft postal matters. Moreover, the device is enabled to print also on postal matters of different sizes such as letters and parcels, securely at the regular position.
In correspondence between the present invention and the arrangement of the above-described one embodiment,

the printing device and postage franking machine of the present invention correspond to the postage franking machine 11 of the embodiment;
the case being similar also with the following,
the printing medium corresponds to the postal matter 19 such as letters and parcels; and
the printing-medium conveyance path corresponds to the conveyor belt 18 and the postage franking machine 11,

Second Embodiment

Next, a second embodiment of the present invention is described in detail with reference to the accompanying drawings.
Fig. 7 shows a postage franking machine 111 equipped with a printing device of the present invention. In this postage franking machine 111, a measuring section 113 for a postal matter A is formed on one side (left side in the figure) of an device body 112, while a stacker section 114 is formed on the other side (right side in the figure). A touch panel 115 as an input operating section is provided between these sections, and further a print head 116 of non-contact type, for example, ink jet type is provided inside the device body 112.
The measuring section 113 measures the weight of postal matters A of different outside dimensions and masses, such as envelopes. The touch panel 115 is used to press displayed selector keys and enter a mail type such as surface mail, registered mail, express mail, domestic/foreign mail, air mail and ship mail. The postal matter A, when moving from the measuring section 113 and passing under the print head 116, will have postage, date or the like printed in a non-contact manner at the proper printing place of the postal matter A by the print head 116, and then stored in the stacker section 114.
Fig. 8 shows the internal construction of the main part. Along a conveyance path 117 for the postal matter A to be conveyed in the direction of arrow "a" are disposed a photoreceiver 121 for receiving, via a polarizing filter 120, reflected light of illuminated light projected from a phototransmitter 118 via a polarizing filter 119 from left to right side as shown in the figure, a touch roller 122 which will make rolling contact with the postal matter A with low frictional resistance, and the print head 116 in this order. In this arrangement, the distance between the light reflecting site and the touch roller 122 is set to L1, the distance between the center of the touch roller 122 and the center of the print head 116 is set to L2, the overall length of the postal matter A is set to Lm, the length necessary for the printed postal matter A to pass through under the print head 116 is set to L3 (where L3 > Lm), and the vertical height between the top face of the postal matter A and the print head 116 is set to h (which is however variable depending on the thickness of the postal matter A, as will be later described).
In addition, the conveyance path 117 is implemented by an endless belt or the like, and the conveyance of the postal matter A is controlled by a postal matter conveyor 123 having a motor (see Fig. 13).
Also, the phototransmitter 118 and the photoreceiver 121 have the polarizing filters 119 and 120, respectively, so as not to be affected by disturbance noise light. Thus, illuminating light of certain specific frequencies is emitted from the phototransmitter 118 and its reflected light is detected by the photoreceiver 121.
If the postal matter A is absent from the phototransmitter/ photoreceiver 118 or 121, the illuminated light from the phototransmitter 118 is transmitted downward, so that the reflected light will not enter the photoreceiver 121. However, if the postal matter A enters (is present at) the phototransmitter/ photoreceiver 118 or 121, the photoreceiver 121 detects the reflected light of the postal matter A.
Fig. 9 shows time-base variations in the amount of light received by the photoreceiver 121 and the pulses of reflected light detected by a differentiating circuit 124. When the cellophane transparent window (hereinafter, abbreviated simply as cellophane portion B) of the postal matter A (see Fig. 15) has passed the phototransmitter/ photoreceiver 118 and 121, the reflected will be irregularly reflected so that the amount of light at the photoreceiver 121 is reduced. By detecting the amount of resultant variation in the reflected light with the differentiating circuit 124, the range Lc (see Fig. 15) of the cellophane portion B of the postal matter A is detected.
Accordingly, the photoreceiver 121 and the differentiating circuit 124 constitute a material detecting means 125 that detects a material portion (non-cellophane portion) proper for printing in the postal matter A. In addition, in Fig. 9, reference character Tm denotes a time period in which the postal matter A passes, and Tc denotes a time period in which the cellophane portion B passes, where these time data will be inputted to a CPU 140, which will be described later.
Fig. 10 shows a concrete arrangement of the touch roller 122 disposed in the stage succeeding the material detecting means 125. A pressure sensor 128 is disposed above a roller holder 126 which rotatably supports the touch roller 122, with a pressure spring interposed therebetween.
The touch roller 122 will make rolling contact with the postal matter A with a relatively weak pressing force so as to detect slight up or down strokes, where any pressure change during the passage of the postal matter A is measured by the pressure sensor 128. That is, as Fig. 11 shows the relationship between pressure P and displacement y, such a linear relationship holds between these P and y, that they proportionally increase or decrease in a linear fashion. Thus, the thickness of the postal matter A can be detected by the pressure sensor 128.
Accordingly, the pressure sensor 128 constitutes a flatness detecting means 129 that detects a flat portion proper for printing in the postal matter A. A portion having no deviation of pressure signals derived from the pressure sensor 128 (deviation between last time and this time values) corresponds to a flat portion of the postal matter A.
Fig. 12 shows a print head lifting device 130 which moves up and down the print head 116 disposed in the stage succeeding the flatness detecting means 129, responsive to the thickness of the postal matter A. A driving gear 133 is attached to an output shaft 132 of a pulse motor 131, while a driven gear 134 that is normally engaged with the driving gear 133 has the print head 116 coupled therewith via a screw 135 and a slider 136. Thus, the print head lifting device 130 is so constructed that the print head 116 is lifted or lowered to a vertical distance h (see Fig. 8) optimum for clear prints by driving the pulse motor 131 forward and reverse. In this embodiment, since a print head 116 of non-contact type such as ink jet type is employed, the vertical distance h is variably adjusted to one that results in the clearest prints by the print head 116, relative to the thickness of the postal matter A.
Fig. 13 shows a control circuit block diagram of the postage franking machine. The CPU 140 drives and controls the print head lifting device 130, the print head 116, the postal matter conveyor 123 and the measuring section 113 based on inputs of various types of signals from the touch panel 115, a print start button 137, the differentiating circuit 124 and the pressure sensor 128, and according to programs stored in a ROM 138. Also, a RAM 139 stores various types of necessary data and tables. In addition, in the embodiment as shown in Figs. 7 through 12, a print head lateral moving device 141 is not employed.
The operation of the postage franking machine having the above construction is described below in detail with reference to the flow chart as shown in Fig. 14.
At step S1, when the user sets a postal matter A to the measuring section 113, the measuring section 113 measures the weight of this postal matter A and outputs a measuring result to the CPU 140. Upon the setting of the postal matter A, the CPU 140 displays various types of selector keys on the touch panel 115, where the user makes an input by pressing any one of the selector keys at which such mail types as surface mail, registered mail, express mail, domestic/foreign mail, air mail and ship mail are displayed. Then the CPU 140 determines an information pattern to be printed on the postal matter A.
Next, at step S2, the user turns ON (inputs by touch) the print start button 137 in the touch panel 115, the program moves to the next step S3. At this step S3, the CPU 140 drives the postal matter conveyor 123, starting to convey the postal matter A along the conveyance path 117.
By this conveyance of the postal matter A, the length (La + Lb) from the end to the cellophane portion of the postal matter A (see Fig. 15) as well as the length Lc of the cellophane portion (see Fig. 15) are first detected by the material detecting means 125. Next, the displacement y of the touch roller 122 that makes rolling contact with the postal matter A is converted into a pressure P by the pressure sensor 128, by which a maximum thickness (hmax) of the postal matter A (which is data that makes a factor for determining the vertical position of the print head 116) as well as a change in the thickness along the longitudinal direction (which is data that makes a factor for detecting a flat portion) are detected, especially, a portion having a step gap and another portion having no step gap are detected.
Subsequently, at step S4, as the postal matter A passes the place where the touch roller 122 is disposed, the program moves to the next step S5. At this step S5, the CPU 140 decides whether or not the postal matter A is printable, where for a decision of YES, the program moves to the next step S6, while for a decision of NO, it skips to step S8 with the purpose of extraction of abnormalities.
At step S6 mentioned above, the CPU 140 decides whether or not it is a position to start printing on the postal matter A (see the timing at which the print head turns ON in the time chart as shown in Fig. 16). For a decision of NO, the program flow stands by until the print start portion for the postal matter A is reached. For a decision of YES, the program moves to the next step S7.
At this step S7, the CPU 140 drives the print head 116 of non-contact type, executing the printing of specified postal information on a non-cellophane, step-gap-free flat portion of the postal matter A as shown in Fig. 15, by which a printed image C is formed. Next, at step S8, the CPU 140 ends the conveyance of the postal matter A, thus completing a sequence of processing.
As shown above, in the process of executing a specified printing on the postal matter A by the print head 116, the detection means (at least either one of the material detecting means 125 or the flatness detecting means 129) detects a proper printing place (in terms of both material and flatness for proper printing) of the postal matter A, while the control means (see the postal matter conveyor 123 and the print head lifting device 130) controls the postal matter A or the print head 116 so that printing is performed at the proper printing place detected by the detection means. As a result, there is produced an effect that it is capable of obtaining a clear printed image C (see Fig. 15) by securely preventing any disappearance or omission of the printed image.
Also, since the material detecting means 125 detects a material portion of the postal matter A proper for printing, there is produced an effect that printing can be effected by selecting a material portion that allows a clear printed image C to be yielded and that has been detected by the material detecting means 125.
Further, since the flatness detecting means 129 detects a flat portion proper for printing in the postal matter A, there is produced an effect that printing can be effected by selecting a flat portion, or non-step-gapped portion, that allows a clear printed image C (see Fig. 15) to be yielded and that has been detected by the flatness detecting means 129.
Furthermore, the moving means (see the postal matter conveyor 123, the print head lifting device 130) moves the postal matter A or the print head 116 so that printing is effected at a proper printing place, there is produced an effect that a clear printed image can be ensured with the print head 116.
Besides, the vertical moving means (see the print head lifting device 130) moves the print head 116 vertically to the conveyance surface of the postal matter A, there is produced an effect that a proper printed image C can be obtained by controlling the vertical position of the print head 116 responsive to the thickness of the postal matter A.
Moreover, since the flatness detecting means 129 has the touch roller 122, a flat portion including no step gaps of the postal matter A can be detected based on the touch roller 122 by putting the touch roller 122 into rolling contact with the postal matter A. As a result, there is produced an effect that a further clearer printing can be achieved.
Still, since the print head 116 is implemented by a non-contact type print head, even a postal matter A having some step gaps of thicknesses can be printed from a separate location away from the postal matter A. Thus, there is produced an effect that a clear printed image C (see Fig. 15) can be obtained.
Fig. 17 shows another embodiment of the postage franking machine. The foregoing embodiment has been so arranged that printing is performed by the print head 116 while the postal matter A is conveyed by the postal matter conveyor 123 in the direction of arrow "a". However, in this embodiment as shown in Fig. 17, with a view to reducing the longitudinal size of the device body 112, it has been arranged that after the postal matter A is once conveyed up to the terminal end of conveyance, the print head 116 in the regular position (normal position) as depicted by solid line in Fig. 17 is moved laterally to the print start position as depicted by imaginary line in the figure, and that after the printing, the print head 116 is moved laterally again and thus returned to the regular position.
In this embodiment, since the print head 116 is moved laterally as described above, a print head lateral moving device 141 as shown in Fig. 13 is employed.
Next, with reference to the flow chart of Fig. 18, the operation of this postage franking machine is described in detail. It is noted that the main part circuit unit shown in the foregoing figures is used also in this embodiment.
At step U1, when the user sets a postal matter A to the measuring section 113, the measuring section 113 measures the weight of this postal matter A and outputs a measuring result to the CPU 140. Upon the setting of the postal matter A, the CPU 140 displays various types of selector keys on the touch panel 115, where the user makes an input by pressing any one of the selector keys at which such mail types as surface mail, registered mail, express mail, domestic/foreign mail, air mail and ship mail are displayed. Then the CPU 140 determines an information pattern to be printed on the postal matter A.
Next, at step U2, the user turns ON (inputs by touch) the print start button 137 in the touch panel 115, the program moves to the next step U3. At this step U3, the CPU 140 drives the postal matter conveyor 123, starting to convey the postal matter A along the conveyance path 117.
By this conveyance of the postal matter A, the length (La + Lb) from the end to the cellophane portion of the postal matter A (see Fig. 15) as well as the length Lc of the cellophane portion B (see Fig. 15) are first detected by the material detecting means 125. Next, the displacement y of the touch roller 122 that makes rolling contact with the postal matter A is converted into a pressure P by the pressure sensor 128, by which a maximum thickness (hmax) of the postal matter A (which is data that makes a factor for determining the vertical position of the print head 116) as well as a change in the thickness along the longitudinal direction (which is data that makes a factor for detecting a flat portion) are detected, especially, a portion having a step gap and another portion having no step gap are detected.
Subsequently, at step U4, as the postal matter A passes the place where the touch roller 122 is disposed, the program moves to the next step U5. At this step U5, the CPU 140 conveys the postal matter A up to the terminal end of conveyance on the right side as shown in Fig. 17, thus ending the conveying process prior to the printing.
Next, at step U6, the CPU 140 decides whether or not the postal matter A is printable. For a decision of NO, the CPU 140 does not execute the processes of step U7 and the following (especially, printing process), thus ending the sequence of processing with the purpose of extraction of abnormalities. On the other hand, for a decision of YES, the program moves to the next seventh step U7. At this step U7, the CPU 140 drives the print head lateral moving device 141, thereby moving the non-contact type print head 116 as shown in Fig. 17 laterally from the position depicted by solid line to the print start position depicted by imaginary line in the same figure.
Subsequently, at step S8, the CPU 140 decides whether or not the print head 116 has been moved to a print start position serving both as a material portion that allows a proper printing and as a flat portion that has no step gap. For a decision of NO, the program flow returns to the foregoing step U7. On the other hand, for a decision of YES, the program moves to the next ninth step U9.
At this step U9, the CPU 140 drives the non-contact type print head 116 as well as the print head lateral moving device 141, executing the printing of specified postal information on a non-cellophane, step-gap-free flat portion of the postal matter A as shown in Fig. 15, while moving the print head 116 from right to left in Fig. 17, by which a printed image C (see Fig. 15) is formed.
After the printed image C has been formed in this way, the CPU 140 makes the print head 116 returned to the regular position as depicted by solid line in Fig. 17 via the print head lateral moving device 141, thus completing a sequence of processing.
In the case of this arrangement, as apparent from a comparison between Fig. 8 and Fig. 17, there is produced an effect that the device can be reduced in size, especially in the longitudinal size. Otherwise, functions and effects similar to those of the foregoing embodiment can be fulfilled and therefore their detail description is omitted only by designating like components by like numerals in Fig. 17. In addition, in Fig. 17, reference character L4 denotes the length between the center of the touch roller 122 and the end of postal matter A that has been conveyed up to the terminal end position of conveyance, where a relation, $L4 < L2 + L3$
, holds. Thus, the embodiment of Fig. 17 achieves a miniaturization of the device, compared with the foregoing embodiment.
In correspondence between the present invention and the arrangement of the above-described embodiment,

the printing medium of the present invention corresponds to the postal matter A of the embodiment;
the case being similar also with the following,
the detecting means corresponds to either one or both of the material detecting means 125 and the flatness detecting means 129; the control means and the moving means correspond to at least one of the print head lifting device 130, the print head lateral moving device 141 and the postal matter conveyor 123;
the vertical moving means corresponds to the print head lifting device 130; and
the print head corresponds to the print head 116 of non-contact type such as ink jet type,

Claims

A printing device for printing on a printing medium conveyed relatively to a print head, the print head being disposed on a conveyance-surface side of a printing-medium conveyance path for conveying the printing medium.
The printing device according to Claim 1, further comprising a V-shaped conveyance surface which is bent into a V shape along a conveyance direction over a lower edge portion of a tilted conveyance surface tilted widthwise of the printing-medium conveyance path.
The printing device according to Claim 2, wherein the print head is disposed at a place near the V-shaped bent portion of the V-shaped conveyance surface.
The printing device according to Claim 1, wherein the print head is implemented by an ink jet type print head.
A printing device having a print head for performing a specified printing on a printing medium, the printing device comprising: detection means for detecting a proper printing place of the printing medium; and control means for controlling the printing medium or the print head so that printing is performed at the proper printing place detected by the detection means.
The printing device according to Claim 5, wherein the detection means is a material detecting means for detecting a material portion of the printing medium proper for printing.
The printing device according to Claim 5, wherein the detection means is a flatness detecting means for detecting a flat portion of the printing medium proper for printing.
The printing device according to Claim 5, wherein the control means has lateral moving means for moving the printing medium or the print head in parallel with the conveyance surface of the printing medium.
The printing device according to Claim 5, wherein the control means has vertical moving means for moving the print head vertically to the conveyance surface of the printing medium.
The printing device according to Claim 7, wherein the flatness detecting means has a touch roller that makes rolling contact with the printing medium to detect any shift in the vertical direction with respect to a conveyance surface of the touch roller.
The printing device according to Claim 5, wherein the print head is implemented by a non-contact type print head.
A postage franking machine equipped with any one of the devices as defined in Claims 1 to 11.