JPS60239265A - Serial printer - Google Patents

Abstract

PURPOSE:To increase the ability of detecting a bulge of printing paper by a construction wherein electroconductive rubber having a characteristic of conduction under pressure is provided between a ribbon shield plate preventing the paper from being stained and a metal fitting fixing said plate in the state of non-conduction. CONSTITUTION:When paper 3 is bulged and a printing head 4 runs in the direction of an arrow (b) and passes through a bulged portion A of the paper causing jamming, a force pressing a ribbon shield plate 13 is about 10N. Meanwhile, electroconductive rubber 17 fixed to the shield plate 13 and a shield fixing plate 11 by an electroconductive adhesive changes at about 3N from the state of non- conduction to that of conduction, and therefore jamming is detected from a signal of detection of said change in the state which is sent to a control circuit. In this way, the bulge of the paper can be detected by a simple construction without necessitating any specific detection switch.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a serial printer, and particularly to a structure for detecting jamming of printing paper in a serial printer.

[Background of the invention]

In known serial printers for word processors, printing paper called cut paper or single sheet is often used. Therefore, for this type of serial printer,
With the addition of an automatic paper feed mechanism, work efficiency has been improved so that once a large number of sheets of paper are set, there is no need for the troublesome task of inserting paper for the time being.

An example of this type of serial printer is shown in FIG.

In this figure, a wire dot matrix print head 4 is fixed to a carrier 5 by screws 6. The carrier 5 is supported by support rails 71 and 72, and is driven by means such as a motor and a timing belt (not shown) to travel in the direction indicated by the arrow, that is, in a direction parallel to the platen 9. A ribbon shield plate 13 is placed on the carrier 5 to prevent the ink ribbon 8 from contacting the printing paper 3 and staining the printing paper 3. A ribbon shield plate fixture 11 is provided, and a ribbon guide 12 is also provided to improve ease of ribbon insertion. Print wires arranged in a matrix in the print head 4 are driven,
Printing is performed on the printing paper 3 by striking the platen 9 through the ink ribbon 8 and the printing paper 3. Feed rollers 101 and 102 are provided on the conveyance path of the paper 3, and by rotating in the direction of the arrow C, the printing paper 3 is fed in the direction of the arrow a. The printed paper 3 is sent in the direction a, and is conveyed and accumulated in a stacker (not shown) below.

However, if a large number of printed sheets 3 accumulate in this stacker, the following problem will occur.

Although such a situation normally does not occur often, it may occur if more sheets than the specified number remain in the stacker due to the operator's carelessness or the like.

In this case, when a new printing paper 3 is further fed into the stacker, the leading edge of the paper gets caught by the already stacked papers and is greatly bent. When this situation progresses and the paper 3 is further conveyed by the feed roller 101, the paper becomes wrinkled because the print head 4 is running. Then, the paper 3 finally breaks.

When the paper breaks, the broken pieces are transferred to the feed roller 10.
1 R-102 or scattered deep inside the printer, and it takes a lot of time to clean these pieces of paper. Further, since the print wire of the print head 4 is very thin, for example, with a diameter of 0.2+m, the print wire may be caught by a step such as a wrinkle in the paper, and the print wire may be broken.

As described above, paper jams significantly reduce the reliability of printers.

As a method for preventing the paper from being torn due to a paper jam and the printing wire from being broken, a method has been proposed in which the floating of the paper is detected and the printing operation is stopped. For example, as an example of this method, it is conceivable to provide an ON-Urr switch having mechanical contacts in order to detect floating of paper. However, this method requires a constant operating stroke, and therefore has a drawback in that the ability to detect sheet lifting is low.

In addition, when sucking and discharging paper, a sliding plate is required to prevent the paper from getting caught on the pusher of the switch, and the mechanical strength is weak.
The disadvantage is that jammed paper is easily damaged when removed.

[Purpose of the invention]

An object of the present invention is to provide a serial printer equipped with a paper floating detection means that detects paper floating using a simple mechanism, has high detection ability, has strong mechanical strength, and has a small number of parts. .

[Summary of the invention]

In a serial printer that prints on print paper via an ink ribbon while the print head runs in a predetermined direction, the present invention has a ribbon shield plate that prevents the ink ribbon from staining the print paper and a ribbon shield plate that is in a non-conducting state. A conductive rubber with pressurized conductive properties is provided between the metal fitting and the metal fitting that is fixed.

Generally, printers have a print head that prevents the ink ribbon from coming into contact with the printing paper and staining the printing paper.
It is equipped with a ribbon shield plate that is open only where necessary for printing.

If printing paper floats due to a jam, it will come into contact with the ribbon shield plate, so if the ribbon shield plate is used as the actuator of the paper float detection switch, paper float detection can be achieved with fewer parts and greater mechanical strength. It can be a sensor.

, Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. Second
The figure is an exploded perspective view showing the paper floating detection mechanism. A plurality of wires are mounted on the print head 4, guided by a nose 41, and arranged in two rows at the tip thereof. The ribbon guide 12 is provided with an opening 121 in the center into which the rad nose 41 enters the print. Ribbon shield plate fixture 11
is provided with a large opening 111. A ribbon is guided between the nose 41 of the print head and the ribbon shield plate 13. Further, a conductive rubber 17 is attached between the ribbon shield plate 13 and the ribbon shield plate fixture 11. This conductive rubber 17 has, for example, pressure characteristics as shown in FIG.

That is, as shown in more detail in FIG. 6, the ribbon shield plate 13 is attached to the ribbon shield plate fixing A11 with only the end portion of the ribbon shield plate 13 bonded 18 in a non-conducting state. The conductive rubber 17 is attached to the ribbon shield plate 13 and the ribbon shield plate fixture 11 using conductive adhesive.
is fixed.

Ribbon shield plate 13. Lead wires are connected to the ribbon shield plate fixture 11, and are connected to a printed circuit board (not shown).

The ribbon shield plate 13 is made of a very thin metal plate, and when the ribbon shield plate 13 is pressed, a conductive rubber 17 shown in FIG. The properties are almost the same as the pressurized conductive properties of .

Next, the operating pressure of the present invention will be explained with reference to FIGS. 4 and 5. As shown in FIG. 4, it is assumed that the paper is floating and the print head 4 is running in the direction indicated by the arrow. If the print head 4 continues to run in this state, it will become as shown in FIG. When the print head passes through the bulge A of the jammed paper, the force pushing the ribbon shield plate 13 is approximately 1 ON. The conductive rubber 17 changes from a non-conductive state to a conductive state at approximately 3N. By sending a detection signal from the conductive rubber 17 to a control circuit (not shown), the control circuit detects the jam and controls the print head to stop running immediately.

This prevents tearing of the paper and damage to the print head.

Note that the paper floating detection means with this structure utilizes the fact that conductive rubber becomes conductive when pressure is applied, so if preload is applied to the conductive rubber, paper floating can be accurately detected. I get busy. Therefore, by preferably providing a small distance between the ribbon shield plate 13 and the conductive rubber 170, it is possible to provide a detection means that requires almost no operating stroke and does not apply preload. In addition, in order to provide this minute gap, when bonding the ribbon shield plate 13 and the ribbon shield plate fixture 11, a thin metal plate is inserted between the ribbon shield plate 13 and the conductive rubber 17, and This can be easily done by removing the metal plate after drying.

〔Effect of the invention〕

According to the present invention, since conductive rubber is used as the paper jam detection means, an operating stroke is almost unnecessary, and the ability to detect paper lifting is improved. In addition, since the ribbon shield plate used in ordinary printers is effectively used, there is no need for a sliding plate, high mechanical strength, no special detection switch, and a simple structure. It is possible to detect floating of paper.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a serial printer mechanism for single-sheet printing according to the prior art, FIG. 2 is an exploded perspective view showing a print head addition mechanism according to an embodiment of the present invention, and FIG. 3 is a characteristic of conductive rubber. 4 and 5 are side views for explaining the operation, and FIG. 6 is a plan view of the printing mechanism section. 3... Print paper, 4... Print head 8... Ink ribbon, 9... Platen 11... Ribbon shield plate fixture 13... Ribbon shield plate 17... Conductive rubber. Representative Patent Attorney Akio Takahashi Figure 1 Figure 3 Reaction force CKi/cw)”)

Claims (1)

[Scope of Claims] 1. In a serial printer that prints on printing paper via an ink ribbon while a print head runs in a predetermined direction, a ribbon shield plate that prevents the printing paper from being stained by the ink ribbon, and a ribbon A serial printer characterized in that a conductive rubber having pressurized conductive properties is provided between a metal fitting that fixes a shield plate in a non-conductive state. 2. The serial printer according to item 1, characterized in that a minute gap is provided between the conductive rubber and the ribbon shield plate.