Line thermal printer head

Abstract: There is provided a line thermal head printer apparatus in which a ribbon tape (2) is moved, only while printing is to be made, synchronously with the moving velocity of the object (18) to be printed, thereby the ribbon tape (2) is moved only by the amount needed for printing and the amount of use of the ribbon tape (2) is reduced and yet a well-defined printing is made. In such a line thermal head printer apparatus a ribbon tape (2) unwound from a heat transfer ribbon tape master roll (1) is superimposed to a packaging material film (8) on a platen roller (6) and a printing is made by a line thermal head (5; 15) on the packaging material film (8). The ribbon tape (2) is stopped by a braking action making use of a maximum static torque characteristic of a stepping motor (3) until a portion to be printed of the packaging material film (8) comes, and is moved correctly by the stepping motor (3) only when the portion to be printed of the packaging material film (8) comes. With the signal from an encoder (10) for detecting a velocity of the packaging material film (8), the stepping motor (3) moves the ribbon tape (2) at a velocity always synchronized with the velocity of the packaging material film (8) and a well-defined printing is made on a predetermined place.

Description: The present invention relates to a line thermal head printer apparatus in which a line thermal head is supplied with electricity and a printing is made on a moving object to be printed by a ribbon tape (carbon tape). In US-A-4 507 667 there is disclosed a line thermal head printer apparatus of the kind referred to above and set out in the preambles of claims 1 or 2. In the recent years, there are many cases where printing of letters and marks, such as date of manufacture, tastable time period, series number of manufacture, etc. on a packaging material for example, are required to be made on the object to be printed, and for this kind of printing, a line thermal head printer apparatus is often used. In the line thermal head printer apparatus in the prior art, following a velocity of a moving object to be printed, such as a film supplied from a master roll of packaging material film for example, a ribbon tape of same length as the moving length of the film is fed for printing. In this type of line thermal head printer apparatus in which a ribbon tape of same length as the moving object to be printed is fed, as a highly expensive ribbon tape is consumed in a large amount, there is a large problem how to suppress the amount of use of the ribbon tape. So, there is disclosed a device in which a ribbon tape is moved only while a printing is being made on an object to be printed and movement of the ribbon tape is stopped otherwise. However, is such kind of device, construction is so made that the movement of the ribbon tape is made always at a constant velocity. Accordingly, in such device in the prior art, when the movement of the ribbon tape is commenced upon the portion to be printed of the object to be printed coming, some rise time is required until the ribbon tape reaches said constant velocity and moreover the transfer velocity itself of the object to be printed varied slightly, thus there occurs a deviation in the relative position of the object to be printed and the ribbon tape, and there is a shortcoming that a clean or clear printing is not always applied to a predetermined place of the object to be printed. It is therefore an object of the present invention to provide a line thermal head printer apparatus in which a ribbon tape is moved only while a printing is to be made on an object to be printed, so that the amount of use of the ribbon tape is remarkably reduced, a rise time of the ribbon tape is short enough and yet the ribbon tape is moved at a velocity always synchronized with the moving velocity of the object to be printed, so that a clean or clear printing can be made. According to the present invention there is provided a line thermal head printer apparatus as set out in claim 1. In the line thermal head printing apparatus according to the present invention, when a portion not to be printed of the object to be printed is moving, the movement of the ribbon tape is stopped by the stepping motor as a brake and only when a portion to be printed of the object to be printed comes, the movement of the ribbon tape is commenced by the stepping motor with an appropriate rise time. The stepping motor is rotated at a speed synchronized with the moving velocity of the object to be printed detected by the velocity detecting device for detecting the moving velocity of the object to be printed, and moves the ribbon tape at a velocity always synchronized with the moving velocity of the object to be printed. The ribbon tape is moved at a velocity always synchronized with the object to be printed even if the moving velocity of the object to be printed varies, partly assisted by an adhesion by a friction resistance and a static electricity between the object to be printed and the ribbon tape, thus a well-defined printing can be applied onto a predetermined place to be printed. For a printing apparatus in which the ribbon tape is moved, only when a printing is being made by a thermal head on the object to be printed, at a velocity synchronized with the moving velocity of the object to be printed, as mentioned above, the present invention further provides a line thermal head printer apparatus as set out in claim 2. According to said printer apparatus, when the portion not to be printed of the object to be printed is being transferred, the ribbon tape, being only pressed against the object to be printed by the presser element, does not move and the object to be printed is transferred or moved slidingly on the surface of the ribbon tape. When the portion to be printed of the object to be printed is coming, the ribbon tape is moved at the velocity synchronized with the object to be printed by the appropriate means as mentioned above and an instantaneous pressing force is added to the presser element by the knock cylinder, thus without a shock such as the added pressing force given by the descent of the thermal head, a clean and well-defined printing can be made on the portion to be printed of the object to be printed. As mentioned above, according to the present invention, there is provided a line thermal head printer apparatus in which a ribbon tape is moved only by a length necessary to make a heat transfer printing and the amount of the ribbon tape is remarkably saved and even if the moving velocity of the object to be printed varies, the ribbon tape is moved at a velocity always synchronized with the object to be printed. BRIEF DESCRIPTION OF THE DRAWINGS: Fig. 1 is an explanatory view showing a line thermal head printer apparatus of a preferred embodiment according to the present invention. Fig. 2 is an arrangement view of machinery and equipment showing the construction of a printing portion of Fig. 1. Fig. 3 is a front view showing the construction of a line thermal head portion of Fig. 2. Fig. 4 is a side view of Fig. 3. Herebelow, a line thermal head printer apparatus according to the present invention is described with reference to the figures of the drawings. Fig. 1 shows a line thermal head printer apparatus of a preferred embodiment according to the present invention, wherein numeral 1 designates a master roll of ribbon tape of the heat transfer type. The ribbon tape 2 unwound therefrom, after being used for printing as described below, is wound around a used tape winding roll 4 fitted on a shaft 9 of DC torque motor. Numeral 5 designates a line thermal head and numeral 6 designates a head receiving platen roller. Between the line thermal head 5 and the head receiving platen roller 6, the ribbon tape 2 from the master roll 1 and an object to be printed, a packaging material film 8 for example, are passed in superimposed arrangement and a previously programmed printing is applied to the packaging material film 8. Numeral 3 designates a stepping motor driven roller and when a printing is not being made on the packaging material film 8, the stepping motor is stopped of rotation and its used as a brake to the ribbon tape 2, making use of its maximum static torque characteristic. Numeral 7 designates a ribbon tape pressing roller. Numeral 10 designates an encoder to detect a transfer velocity of the packaging material film 8, and the stepping motor is constructed so as to be controlled as to the rotational speed by the signal detected thereof. As the line thermal head printer apparatus shown in the figure is so constructed as mentioned above, when a printing is not necessary to be made on the packaging material film 8 which is an object to be printed, the stepping motor is stopped of rotation and is used as a brake to the ribbon tape 2, making use of its maximum static torque characteristic, and the moving of the ribbon tape 2 is also stopped. When a printing is to be made upon the portion to be printed of the packaging material film 8 coming, a control is made so that by a signal of the encoder 10 for detecting the moving velocity of the object to be printed, the stepping motor moves the ribbon tape 2 at a velocity synchronized with the transfer velocity of the packaging material film 8 and the line thermal head 5 is supplied with electricity so that a printing is made by the ribbon tape 2. The ribbon tape 2 is moved correctly at a continuous velocity synchronized with the transfer velocity of the packaging material film 8, partly assisted by an adhesion to the packaging material film 8 by friction resistance and a static electricity, thus the ribbon tape 2 is efficiently used and a well-defined printing can be made. One example of concrete construction of said line thermal head 5 is shown in Fig. 2 to 4. In Fig. 2 to 4, numeral 11 designates a knock cylinder fitted to a fitting plate 12, a piston rod 13 of which is provided with a presser element 14, numeral 15 designates a thermal head, which is fitted cantileverwise rotatably around a pin 16 via a head fitting plate 17 so as to be movable up and down as shown by arrows of Fig. 3. Thus, the thermal head 15 is in a state that it is put on a platen roller 6 so that the ribbon tape 2 is always pressed against the packaging material film 8 by the self-weight (dead load) of the thermal head 15 (about 1.2 kg/cm 2 as one example). When a portion not to be printed of the packaging material film 8 is being moved, the ribbon tape 2 is stopped as mentioned above, thereby the packaging material film 8 is transferred or moved slidingly on the surface of the ribbon tape 2. When the portion to be printed of the packaging material film 8 is coming, the ribbon tape 2 is fed by the stepping motor 3 and is wound by the DC torque motor, thereby the ribbon tape is moved at a velocity equal to the packaging material film 8. At the same time, the knock cylinder 11 is operated so that the ribbon tape 2, which is being pressed against the packaging material film 8 by the self-weight (dead load) of the thermal head 15 as mentioned above, is given an instantaneous cylinder pressure and printing is made. When the printing is finished, operation of the knock cylinder 11 is stopped and the ribbon tape 2 returns to a state in which it is pressed against the packaging material film 8 by the self-weight (dead load) of the thermal head 15. Thus, the ribbon tape 2, as it is being pressed against the packaging material film 8, is pushed to make a printing only at the time of operating of the knock cylinder 1, and a printing without giving an impact force to the ribbon tape 2 or the packaging material film 8 can be made. As mentioned above, according to the present invention, a control is made so that the ribbon tape is moved, only for the portion to be printed of the object to be printed, synchronously with the moving velocity of the object to be printed, and the line thermal head is supplied with electricity to make a printing. Thus the ribbon tape is transferred effeciently corresponding to the object to be printed and a well-defined printing can be made on an economical manner. While the preferred form of the present invention has been described, variations thereto will occur to those skilled in the art within the scope of the present inventive concepts.

Claims: A line thermal head printer apparatus in which a printing is made on a moving object (8) to be printed by use of a thermal head (5; 15), a ribbon tape (2) and a platen roller (6) comprising a stepping motor (3) for moving the ribbon tape (2), only when a printing is to be made on said object (8) to be printed, characterized by a velocity detecting device (10) for detecting a moving velocity of the object (8) to be printed and said stepping motor (3) is moving the ribbon tape (2), only at the time of printing at a velocity synchronized by said detecting device (10) with the moving velocity of the object (8) to be printed. A line thermal head printer apparatus in which a printing is made on a moving object (8) to be printed by use of a thermal head (5; 15), a ribbon tape (2), and a platen (6) comprising a stepping motor (3) for moving the ribbon tape (2), only when a printing is to be made on said object (8) to be printed, as claimed in claim 1, further characterized by a presser element (14) for pressing the thermal head (5; 15) constantly against the object (8) to be printed via the ribbon tape (2), and a knock cylinder (11) for applying an instantaneous pressing force acting on said presser element (14) at the time of printing.

Inventors: SOGABE MASUO, TAZAKI RIBUN, SOGABE, MASUO, TAZAKI, RIBUN
Applicants: DAISEY KIKAI CO LTD, DAISEY KIKAI CO., LTD.
Application year: 1996
Main classification: B65B61
IPC codes: B41J33, B65B61