JPH03253382A - Thermal printer - Google Patents

Abstract

PURPOSE:To miniaturize an apparatus by installing a photosensor used both for detecting a medium mark and for detecting a head-up state in the position of facing a printing medium approach path in the bridge part of a head-up lever for retreating a thermal head from a platen. CONSTITUTION:Because a photosensor S is installed in the position of facing a printing medium approach path 6 of a bridge part 11, it can detect whether or not there are a printing paper and printing paper mark. Also, because the photosensor S is installed at the bridge part 11 formed into an integral body with a rotating head-up lever 5, the photosensor S of the bridge part goes toward the outside of the device and a detection light reflects externally of the device when the head-up lever 5 is operated for setting paper, etc., to push up the thermal head from the platen to make it retreat. Consequently, the detection light cannot reflect to enter the photosensor S so that detection becomes impossible. When the head-up lever 5 is operated and the photosensor S cannot function, it is possible to recognize that printing is impossible.

Description

[Detailed Description of the Invention] [Summary] Regarding a thermal printer that has a function to detect print media and media marks, the present invention provides a function to detect print media and media marks as well as a function to detect a head-up state without increasing the size of the device. The purpose of this thermal printer is to realize a thermal printer that can be equipped and is easy to handle, and in which a thermal head and a platen are arranged facing each other with a print medium in between, and the shaft of the platen is inserted through both ends of the platen. It has a shaft support and a bridge part that straddles the platen and connects both shaft supports, and is provided with a head push-up part that retracts the thermal head from the platen and a head-up lever that operates the head push-up part. A detection photosensor is attached to the bridge portion at a position facing the printing medium entrance path, and the output signal of the photosensor is used to detect the presence or absence of the printing medium and to detect media marks. The signal is also configured to be used as a signal for detecting the head-up state of the thermal head.

(Industrial Application Field) The present invention relates to a thermal printer having a function of detecting print media and media marks.

[Conventional technology]

FIG. 5 is a perspective view showing the entire structure of a conventional thermal printer. Reference numeral 1 denotes a platen, which is connected to a motor M via a reduction gear 2. Further, a paper feed knob 3 is fixed to the shaft of the platen l, and a thermal head 4 is disposed opposite to the platen l.

A head-up lever 5 is rotatably attached to the shaft of the platen l. The paper that will be the print medium is indicated by arrow a.
As shown in , the paper is fed into the feed port 6 on the lower side of the platen 1, and is sent between the platen l and the thermal head 4,
It will be printed.

In preparation for setting paper between the platen l and the thermal head 4, the thermal head 4 is rotatably supported on a support shaft 7, and the thermal head 4 rotates around the support shaft 7. and can be evacuated from platen 1.

FIG. 6 is a perspective view of the head-up mechanism in the thermal printer, and FIG. 7 is a side view of the head-up mechanism. The shaft 8 of the platen 1 passes through the shaft support 9.10 of the head-up lever 5 and is connected to the device frame Fl in FIG.
, is supported through F2. Head up lever 5
The shaft supports 9 and 10 are the bridge portion 1 that straddles the platen 1.
They are connected by 1.

Integrally therewith, there is provided a head push-up section 12 for retracting the thermal head 4 from the platen l.

That is, when the hand assembly lever 5 is pushed in the arrow a2 direction, the shaft support 9.10 and the bridge part 11 rotate about the platen shaft 8 in the arrow az force direction, and as shown by the chain line, the head push-up part Since the thermal head 4 is pushed up at 12, the thermal head 4 rotates around the support shaft 7 and retreats from the platen 1.

In this manner, with the thermal head 4 retracted from the platen 1, the printing paper 13 is inserted between the platen 1 and the thermal head 4, and centing is performed.

By the way, in order to detect the presence or absence of printing paper 13 and to determine the printing start position, a photosensor S is provided as shown in FIG. 7. Reference numeral 14 denotes a printed circuit board to which a photosensor S is attached, and is arranged at intervals above the entrance path of the printing paper 13.

Therefore, when the end of the printing paper 13 passes under the photo sensor S, it is possible to detect that the printing paper has been consumed, and to stop the printing operation or notify the operator.

In addition, if the printing paper 13 is label paper, etc., the eighth
As shown in the figure, a cue mark 15 is printed on the back side of the paper at a predetermined distance l from each print start position.

By detecting this with the photosensor S and starting printing after feeding the paper a predetermined distance, it is possible to always start printing from a predetermined position on the label paper.

[Problems to be Solved by the Invention] In the conventional device, as shown in FIG. 7, the printed circuit board 14 having the photosensor S must be provided outside the thermal printer, resulting in an overall large size and When setting the printing paper 13,
must be passed under the printed circuit board 14, which is inconvenient to handle. This is an obstacle to downsizing, especially in small, handy devices, and since the devices are handled by amateurs, there is a need to simplify paper setting.

In addition, in order to prevent paper feeding or printing from being performed in the head-up state as shown by the chain line, a microswitch MS or the like is provided on the back of the head-up lever 5. A signal indicating that the thermal head 4 is separated from the platen 1 is obtained by utilizing the fact that the thermal head 5 is separated from the microswitch MS. This micro-sinch MS is also a factor in increasing the size of the device and also obstructs lever operation.

The technical problem of the present invention is to address these problems and to provide a device that can be equipped with a function to detect printing paper and media marks and a head-up state without increasing the size of the device, and which is easy to handle. The goal is to realize a thermal printer.

[Means for Solving the Problems] FIGS. 1 and 2 are a side view and a perspective view illustrating the basic principle of a thermal printer according to the present invention.

The head-up lever 5 rotates around the shaft 8 of the platen 1 to retract the thermal head 4 from the platen 1.

Reference numeral S denotes a photosensor for detecting print media and marks, and is attached to a position facing the print medium entrance path 6 on the bridge portion 11 that is integrated with the head-up lever 5 that rotates as described above.

The output signal of the photosensor S is also used as a signal for detecting the presence or absence of a print medium and a mark on the medium, as well as a signal for detecting the head-up state of the thermal head 4.

[Effect]

As described above, the photosensor S in the present invention is attached to the bridge portion 11 at a position facing the print medium entrance path 6, and therefore cannot detect the presence or absence of printing paper or the presence or absence of a mark on the printing paper. I can do it.

In addition, since the photo sensor S is attached to the bridge part 11 that is integrated with the rotating head-up lever 5,
To set paper, etc., operate the head up lever 5 and move the thermal head 4 to the platen 1 as shown by the chain line.
When the bridge part is pushed up and retracted, the photosensor S in the bridge section is directed toward the outside of the device, and the detection light is reflected toward the outside of the device. Therefore, it becomes impossible for the detection light to be reflected and incident on the photosensor S, making detection impossible. In this way, when the head-up lever 5 is operated and the photosensor S becomes inoperable, the thermal head 4 is retracted from the platen l by detecting the state of the photosensor S at that time, and the printing becomes impossible. It can be recognized that

(Example) Next, how the thermal printer according to the present invention is actually implemented will be explained using an example. FIG. 3 is a perspective view showing an example of the thermal printer according to the present invention. In the example, two sets of platens 1.1 are installed on the same axis so that two print media 13a and 13b can be fed simultaneously and printed by two thermal heads 4.4.This device is suitable for printing receipts for customers and journals for copies at the same time, such as in stores.

When the idea of the present invention is implemented in such a two-head type device, the photosensors are also
Two pieces are mounted corresponding to each printing paper 13a, 13b. And each photo sensor SL,
S2 is used independently for detecting the printing start position of the printing papers 13a and 13b.

However, for head-up detection, it is sufficient to use only one of the photosensors Sl or S2, but if both are used, it can be used as an auxiliary device in the event that one photosensor does not function, and reliability is increased. It increases.

Note that the photosensors S, Sl, 52 are not limited to reflective types, and may be transmissive types.

FIG. 4 is a diagram showing an embodiment of a detection circuit in a thermal printer according to the present invention. The photo sensor S is controlled by the light emitting element Sa and the light receiving element sb, and when the printing paper 13 is present, the light generated from the light emitting element Sa is transmitted to the printing paper 13.
The printing paper 1
3 exists, and the printing operation continues.

When the reflected light no longer reaches the light receiving element sb, the comparison circuit 1
Since the potential at the comparison terminal 6 changes and the output signal changes, the control section determines that the printing paper is out and stops the printing operation.

In addition, as shown by the chain line in Fig. 1, the head up lever 5
When the thermal head 4 is pushed up from the platen l and retreated, the photosensor S in the bridge section is
Toward the outside of the device, the light receiving element sb can no longer receive reflected light. Therefore, the comparator circuit 16 enters the same state as when the printing paper runs out, and the printing operation is stopped.

Note that when the cue mark 15 on the printing paper 13 is detected, the same state as that of printout occurs, but soon the printing paper 13
is detected, so if the off time of the light receiving element sb is momentary, it is determined to be a cue mark, and the printing operation can be continued.

〔Effect of the invention〕

As described above, according to the present invention, in the bridge portion 11 of the head up lever 5 for retracting the thermal head 4 from the platen 1 by rotation, a medium mark is detected at a position facing the print medium entrance path 6. A photosensor is installed for both head-up and head-up state detection.

As a result, coupled with the fact that one sensor can be used for both purposes, it is possible to attach it directly to the bridge part 11, so it is possible to attach a photo sensor for mark detection outside the device as in the past, or a micro switch for detecting the head-up state. The device is smaller compared to the structure to which it is attached.

Moreover, compared to the conventional structure in which the printed circuit board 14 is mounted in front of the print medium entrance path 6, the print medium is easier to set and handle, and it does not get in the way of lever operation. There is no such thing.

[Brief explanation of drawings]

1 and 2 are a side view and a perspective view explaining the basic principle of the thermal printer according to the present invention, FIG. 3 is a perspective view showing an embodiment of the thermal printer according to the present invention, and FIG. 4 is a thermal printer according to the present invention. A diagram showing an example of a detection circuit in a printer, FIG. 5 is a perspective view showing the entire structure of a conventional thermal printer, FIG. 6 is a perspective view of a head-up mechanism in the same thermal printer, and FIG. 7 is a rad-up mechanism in the same. FIG. 8 is a plan view illustrating the printing paper. In the figure, 1 is a platen, 4 is a thermal head, 5 is a head-up lever, 6 is a print medium entrance path (paper feed port),
7 is the support shaft of the thermal head, 8 is the platen shaft, 9.10
11 is a bridge part, 12 is a head push-up part, 13.13a, 13b is a printing paper (printing medium), 14
15 is a printed circuit board, 15 is a mark, 5SSt, S2 is a photosensor, and MS is a microswitch. English 1 diagram

Claims (1)

[Claims] The thermal head (4) and the platen (1) are connected to the print medium (1).
3), the platen (1) has shaft supports (9) and (10) through which the shaft (8) of the platen (1) is inserted, at both ends of the platen (1), and the platen (1). It has a bridge part (11) that straddles the shaft supports (9) and (10), and integrally connects the thermal head (4) with the platen (1).
) and a head-up lever (12) for operating the head push-up part (12).
5), a detection photosensor (s) is attached to the bridge portion (11) at a position facing the print medium entrance path (6), and the photosensor (s) 2.) A thermal printer characterized in that the output signal of ) is also used as a signal for detecting the presence or absence of a print medium and a medium mark, as well as a signal for detecting a head-up state of the thermal head (4).