GB2254048A - Thermal printhead with plural lines of printing elements. - Google Patents

Abstract

A heat sensitive line-recording head 17 of a video printer, comprises a plurality of parallel heat element lines 19a, 19, the elements of which can generate heat simultaneously. A printer equipped with such a printhead can print two lines of dots simultaneously, and then indexes the paper by twice the line spacing before recording the next two lines. Printing is thereby speeded up. <IMAGE>

Description

1 22549421 VIDEO PRINTER This invention relates to recording heads for

video printers, and particularly, to heat sensitive recording heads.

Video printing equipment is known for printing a picture record of a picture signal acquired instantaneously, or a pictorial image to be reproduced on a monitor by a recording device such as a still camera.

Generally, a video printer utilizes a method of heat conduction of consecutively sublimating three colors of Yellow, Magenta, and Cyan on a heat sensitive recording paper, and it is possible for the three colors to express a color tone freely, and all colors, by synthesizing the three colors.

Figure 1 of the accompanying diagrammatic drawings is a schematic diagram of a conventional video printer; Figure 2A of the accompanying diagrammatic drawings is a front view of a heat sensitive recording head of the conventional video printer; and Figure 2B of the accompanying diagrammatic drawings is a side cross sectional view of the heat sensitive recording head of the conventional video printer.

Referring to Figures 1 and 2, a known video printer comprises an ink ribbon 5 spread consecutively with the three colors of Yellow, Magenta, Cyan (hereinafter called as "Y", "M", "C") and advanced by a driving reel 1 and a supply reel 2, a platen drum 3 installed under the ink ribbon 5, and a heat sensitive recording head 4 installed above the ink ribbon 5. A heat sensitive record paper 6 is placed between a circumference surface of the platen drum 3 and the ink ribbon 5.

When the platen drum 3 is rotated, the record paper 6 fixed on the platen drum 3 and the ink ribbon 5 is advanced by a frictional force at a speed of the platen drum 3, and the heat sensitive recording head 4 generates heat. A heat generating device 9 of the heat sensitive recording head 4 sublimates the colors by pressing the ink ribbon on the recording paper 6 as heat is generated. The record paper absorbs the sublimated dyes, and is thus printed upon.

The heat generating device 9 of the heat sensitive recording head 4 comprises hundreds of heat elements, which are configured in a line. The heat sensitive recording head 4 performs a print of one line of print while the record paper 6 advances consecutively by one pitch, the pitch being that between two dots of feed line in a scanning direction.

Accordingly it takes a considerable time for the heat generating device of the heat sensitive recording head 4 to form a certain picture frame. As it is possible to secure a clear pictorial image only by way of advancing one heat element line of a heat generating device by a predetermined pitch, a high accuracy of movement of the heat generating device is required.

Preferred embodiments of this invention aim to enable a reduced transmission time in a video printer by providing a heat sensitive recording head comprising a plurality of heat element lines which generate a heat simultaneously.

Another aim is to secure a clear pictorial image by maintaining a uniform distance between the plurality of heat element lines without moving the heat sensitive recording head or a record paper while the plurality of heat element lines generate heat simultaneously.

According to a first aspect of the present invention, there is provided a heat sensitive recording head for a video printer, the head comprising:

a heat generating device which is for sublimating a dye and comprises a plurality of heat element lines.

Preferably, said dye is applied on an ink ribbon.

Preferably, said heat generating device of said heat sensitive recording head comprises two heat element lines.

The invention includes the heat sensitive recording head in combination with a platen drum which is operated by a stepping motor.

Preferably, the heat sensitive recording head is so arranged to operate that a rotation of said platen drum is stopped while said heat sensitive recording head records a pictorial image on a record medium, and said platen drum is subsequently rotated to advance said record medium.

Preferably, said pictorial image is recorded by means of said plurality of heat element lines simultaneously.

The invention includes a video printer having aheat sensitive recording head according to the above aspect.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to Figures 3 and 4 of the accompanying diagrammatic drawings, in which:

Figure 3A is a front view of a heat sensitive recording head according to one example of a specific embodiment of the present invention; Figure 3B is a side cross sectional view of the heat sensitive recording head; and Figure 4 is a view of the example of the specific embodiment of Figures 3, as applied to a video printer.

Referring to Figures 3A, 3B and 4, a heat sensitive recording head for a video printer comprises a heat generating device having two or more lines of heat elements 19a and l9b installed in parallel to each other and spaced apart by a space the same as that of a pitch between two adjacent dots in a direction of feed. The heat element lines 19a, 19b are configured so as to press a record paper fixed on a platen drum 13 with a uniform force. The heat generating device can comprise a plurality of any number of heat element lines as required, but every heat element line should be configured so as to contact with the record paper uniformly. The platen drum 13 does not rotate until an ink ribbon contacted on the record paper is sublimated completely.

A first line of the record paper to be printed is advanced to a position under the heat element line 19a by a high speed driving means such as a stepping motor after completing a sublimation of dyes. Such a stepping motor can be utilized for driving the platen drum in short and uniform angular movement rather than continuously.

i An example of operation of the video printer is described in detail as follows.

When the video printer is started, the record paper is transmitted to a circumference surface of the platen drum 13 by a feeding roller (not shown in drawings). The heat sensitive recording head 17 presses the ink ribbon which is supported by a driving reel and a supplying reel, on the record paper fixed on the platen drum 13. At this time, the heat element lines 19a, 19b which project from a substrate 18 of the heat sensitive recording head 17 presses the ink ribbon and the record paper so as to make the three parts contact closely for optimum printing.

The plurality of heat element lines 19a, 19b of the heat sensitive recording head generates heat as soon as data is transmitted to the heat sensitive recording head 17. The heat generated by the plurality of heat element lines 19a, 19b sublimates the dyes of the ink ribbon, and two lines of the record paper are printed simultaneously. After printing the two lines, the record paper and the ink ribbon are advanced rapidly at the same time as the platen drum 13 by a given distance by the stepping motor. A third line of the record paper to be printed is advanced to a position under the first heat element line 19a, and thereafter the third and fourth lines of the record paper are printed simultaneously likewise.

The printing is performed by repeating the step-by-step operation as described as above.

If the heat sensitive recording head comprises more than two heat element lines, a number of movements of the record paper is reduced proportional to the number of heat element lines because the number of lines of the record paper are printed simultaneously, and the first new line of the record paper is positioned under the first heat element line at every operation.

In conclusion, the illustrated heat sensitive recording head comprising a plurality of heat element lines may reduce printing time by printing a plurality of lines of record paper, and may improve picture quality by reducing a number of movements of the record paper advanced by the platen drum.

is The reader's attention is directed to all papers and documents which are filled concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

1 The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims (8)

1. CLAINIS r 1. A heat sensitive recording head for a video printer, the head

   comprising:

   a heat generating device which is for sublimating a dye and comprises a plurality of heat element lines.
2. 2. A beat sensitive recording head as claimed in claim 1, in which said dye is applied on an ink ribbon.
3. 3. A heat sensitive recording head as claimed in claim 1 or 2, wherein said heat generating device of said heat sensitive recording head comprises two heat element lines.
4. 4. A heat sensitive recording head as claimed in Claim 1, 2 or 3, in combination with a platen drum which is operated by a stepping motor.
5. 5. A heat sensitive recording head as claimed in Claim 4, so arranged to operate that a rotation of said platen drum is stopped while said heat sensitive recording head records a pictorial image on a record medium, and said platen drum is subsequently rotated to advance said record medium.
6. 6. A heat sensitive recording head according to claim 5, wherein said pictorial image is recorded by means of said plurality of heat element lines simultaneously.
7. 7. A heat sensitive recording head substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.

   r
8. 8. A video printer having a heat sensitive recording head according to any of the preceding claims.