Ball-point pen

Details Ball-point pen Ball-point pen

2000-05-04

2002-01-22

Walczak, David J. (Department: 3751)

Coating implements with material supply

Including ball, roller or endless-belt tool

Ball

C401S106000, C401S110000, C401S214000

Reexamination Certificate

active

06340261

ABSTRACT:

TECHNICAL FIELD
The present invention relates to an improvement of a ball-point pen having a ball valve mechanism at the point, by pushing a writing ball at the pen point with an elastic body at all times, wherein a ball serving as a writing portion is prevented from slipping out and fitted loosely, in the state having a space of a proper size to ensure a channel of the ink. More specifically, the present invention relates to an improvement relating to solve drawbacks such as a play of the ball, writing characteristics, shock resistance, vibration starving or the like of ball-point pen with an oil-based or water-based ink or a clicking-type ball-point pen, having a medium viscosity ink.
BACKGROUND ART
Conventionally, as a ball-point pen type writing instrument, there can be mentioned: a so-called oil-based ball-point pen with an ink having a high viscosity (about 10,000 cp), using a higher alcohol solvent as a main solvent, is directly contained in an ink container tube; a so-called water-based ball-point pen with an ink having a low viscosity (from 2 to 3 cp), using water as a main solvent is stored in a bundle of fibers, referred to as slivers; and a neutral ball-point pen having intermediate properties of oil-based and water-based ball-point pens. Since the oil-based ball-point pen has a high viscosity, the manner that writing sensation is heavy, lots of blobbing is caused, and since the ink is directly stored, if air comes into the point, a trouble of back leaking of the ink is easily caused. On the other hand, the water-based ball-point pen has such disadvantages that the remaining amount of the ink cannot be confirmed, that the ink easily spreads out onto the face of a document, that since members such as slivers and intermediate feed do not discharge all the ink, the life span is short, and that barrel cylinder becomes thick. With the neutral ball-point pen for solving these drawbacks, back leaking can be almost resolved by means of a mechanism of prevention of back leaking, such as a ball valve. The present applicant has already proposed an invention of a neutral ball-point pen of a type in which a writing ball is pushed with a small load at all times toward inside of the pen point, but when adopting the invention for an actual writing instrument, drawbacks described below were found, and further improvement became necessary.
With a ball-point pen of a type in which the writing ball is pushed by an internal elastic body, there is a case where a ball seat and a point portion are worn away by the ball, with the progress of writing, and though the ink still remains, the ball slips out, thereby the ball-point pen cannot be used anymore for writing. In particular, in the case where a coloring agent of the ink is a pigment type ink with a solid fine powder being dispersed, or in the case where the ink is a water-based ink using water having poor lubricity as a base, or in the case where the oil-based ink is an ink having a viscosity of a medium level (from 10 to 5000 cp at 25° C.), these drawbacks are easily caused, due to wear caused by the solid component, or because of discontinuity of the ink film which tends to occur during ball rotation. As measures against these, there has been considered a measure in which a material of the ball and a tip holder is changed to a material such as a stainless steel having a high hardness, but in that case, there are such disadvantages that machining of the tip holder becomes difficult in proportion to the hardness, and the pen point becomes expensive. Also, when an improvement is performed with an ink, if a lubricant is blended into the ink in a large amount, these disadvantages are alleviated. Due to the lubricant, however, the ink tends to cause spreading on the face of a document, and a drawback of forward leaking, that is, the surface tension of the ink decreases to make the pen point easy to be wet, and when the pen is turned downward, the ink leaks out from the pen point. Thus, it has been found that a simple improvement with an ink is also difficult.
Furthermore, for a ball-point pen using a volatile ink, an elastic body is provided for pushing the writing ball at all times in order to prevent an ink from being volatilized when the ball-point pen is not used for writing, or to prevent starving, or in the worst case, back leaking of the ink caused by the air caught up from the pen point due to an impact such as being dropped or the like, or a so-called forward leaking, that is, the ink is dripping from the pen point. When a pushing force was increased for improving the effect, the forward leaking preventing characteristics was improved, but internal wear and, in the worst case, slipping out of the ball were caused due to writing. In the case of a clicking-type ball-point pen, there is a further drawback that at the time of accommodating a writing element serving as a writing body, the writing element is accommodated with an impact to cause the ball much easier to slip out. Furthermore, when a diameter of the writing ball increases, it favors prevention of the wear, but starving becomes more easily caused due to an impact because of the air brought up from the tip, compared to the case of the writing ball with a small diameter. As a measure against these drawbacks, there is proposed a measure in which a rubber or a spring is inserted between the writing element and the inside of the barrel cylinder, for absorbing the impact. However, with this ball-point pen, there is caused a drawback in that the rubber or the like for absorbing the impact is deformed at the time of writing, causing the pen point to move back and forth, to thereby make writing difficult. Also, another drawback occurs in that since the number of parts increases and it is necessary to consider a method for fixation, the cost also increases.
In particular, with a so-called neutral ball-point pen using an ink having a viscosity intermediate between the oil-based ball-point pen and the water-based ball-point pen, the above-mentioned drawbacks are more likely to occur. However, though being rather insufficient as a ball-point pen, the neutral ball-point pen is put on the market, since other advantages thereof are recognized. Some invention of ball-point pens in which these drawbacks are solved have been proposed occasionally, however, it is still necessary to solve a drawback of wear within the pen point and a drawback of starving resulting from the low impact resistance, considering the productivity, the cost and correlation with the clicking mechanism, including a new demand arising from needs of bold or fine tips.
The present invention is directed to an improvement of a so-called ball-point pen type writing instrument, wherein a ball serving as a writing portion is fitted loosely to the inside a point assembly of popular type, in a state protruding from the point yet not to slip out, and more specifically, the present invention is directed to an improvement of a ball-point pen having an ink having a medium viscosity. A major object of the present invention is to solve a drawback that writing becomes impossible with the ink still remaining inside before the life span as a pen body is finished, while ensuring the writing sensation from the initial stage as writing proceeds. Moreover, another object of the present invention is to provide a writing instrument having excellent performance at a low cost, without requiring an ink of special blend or an advanced mechanism, by solving drawbacks such as starving due to a diameter of a writing ball, or starving and slipping out of the ball due to a return impact in the case of a clicking type ball-point pen, without sacrificing the productivity and performance of the ball-point pen.
DISCLOSURE OF THE INVENTION
The ball-point pen of the present invention devised to solve the above described drawbacks is so configured that a ball serving as a writing portion rotatably protrudes, at distal end while prevented from slipping out, and an ink is accommodated within an ink container tube. It is constructed such that the ink is led out

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