Type

Abstract

 Disclosed is a type which, having a printing surface (14) protruding from a body, is used in printing machines, such as typewriters, printers, etc., and adapted to reproduce a character on printing paper when caused to impact against the paper for printing. A joint edge (16) is formed at each corner portion (x) of the printing surface (14) where two adjacent edge lines (15) defining the printing surface (14) meet so that the joint edge (16) is continuous with the adjacent edge lines (15), whereby a dull print edge, which may otherwise be produced at the corner portion (x) during printing operation, is canceled. The joint edge forms an angle (p) narrower than the angle (a) formed between the adjacent edge lines.

Description

[0001] This invention relates to types which, having an integral printing surface and constituting a type font, may be used in printing machines, such as typewriters and daisy-wheel printers, and adapted to reproduce characters, such as letters, figures, signs, etc., on printing paper when caused to impact against the paper for printing.

[0002] Conventional types of this kind have a printing surface which, bearing a character thereon, protrudes from a body so that a beard is formed between the body and the printing surface.

[0003] In these prior art types, the printing surface representing, e.g., letter A or B, is defined by edge lines so as to be shaped like letter "A" or "B".

[0004] As shown in Fig. 3, however, if a type 2 having such a printing surface 1 is used to reproduce a matrix print on a printing sheet (p) moving relatively to the type 2 in the printing direction (t) by impact printing through a transfer medium (r), such as a carbon or ink ribbon, the printed character on the sheet (p) may involve dull print edges which will blur the outline of the character.

[0005] Figs. 1 and 2 are enlarged views showing the upper left portion of letter "B" and the top portion of letter "A", respectively. In these drawings, broken lines represent contours of the printing surface 1 of the type at those portions corresponding to the illustrated portions of letter "B" or "A", while solid lines indicate contours of printed characters produced by the printing surface 1. The contours of the printing surface 1 and each printed character are coincident except for the corner portions (a), (b) and (e).

[0006] As seen from Figs. 1 and 2, the contours of the corner portions (a), (b) and (e) of the printed characters are arcuate, lacking in sharpness in shape. In other words, the printed characters involve dull print edges (s) at the corner portions.

[0007] In Fig. 1, the printing surface 1 is defined by sharp, rectangular edges, as indicated by broken lines, at a convex corner portion (a) where two adjacent outer edge lines (c) defining an outside contour of the printing surface 1 meet or cross each other, and at a concave corner portion (b) where two adjacent inner edge lines (d) defining an inside contour meet or cross each other. On the other hand, the printed character inevitably involves the arcuate dull print edge (s) recessed from the outside contour of the printing surface 1 at the convex corner portion (a), and the arcuate dull print edge (s) protruding from the inside contour at the concave corner portion (b).

[0008] Also in Fig. 2, a sharp, acute-angled contour of the printing surface 1, as indicated by broken line, at a concave corner portion (e) where two adjacent inner edge lines (d) meet or cross each other, produces a printed character which inevitably involves an arcuate dull print edge (s) protruding from the contour, as indicated by solid line.

[0009] Fig. 4 is an enlarged view of that portion of the printing surface 1 shown in Fig. 1, for illustrating the cause of production of the dull print edges at the corner portions (a) and (b). In Fig. 4, the impact on the transfer medium (r) is represented by isobaric lines (1) around the printing surface 1. The impact causes a pressure to be applied not only to the printing surface 1 but also to regions at some distance from the line edges (c) and (d) defining the printing surface 1, in inverse proportion to the distance. At positions along an isobaric__line (1₁), among other lines (1), the character is printed on the printing sheet (p) through the transfer medium (r) under the same pressure. If the transfer medium (r) is a carbon ribbon, a carbon layer of the ribbon is separated by the impact to be transferred to the surface of the printing sheet (p).

[0010] Around the convex and concave corner portions (a) and (b) where the adjacent edge lines (c) and (d) meet, the isobaric lines (1) are arcuate in shape, unlike the sharp-edged contours at the corner portions. At the convex corner portion (a), for example, the isobaric lines (1) from arcs of concentric circles around the corner point (0).

[0011] The reason is that the impact along the edge lines (c) at the convex corner portion (a) is gradually reduced to become insufficient as the corner point is approached, while the impact along the edge lines (d) at the concave corner portion (b) gradually increases to become excessive as the extreme corner is approached.

[0012] This is regarded as the reason why the dull print edges (s), as shown in Fig. 1, are produced at the corner portions (a) and (b). The dull print edge (s) of Fig. 2 is considered to be produced at the corner portion (e) for the same reason.

[0013] Beside the aforesaid reason, the causes of the production of the dull print edges may practically include various other factors, such as the tension of the transfer medium (r), the impact of the type 2, the quality of the printing sheet (p), etc.

[0014] Thus, in the case of types having a printing surface shaped like the outline of the character to be printed, undesired dull print edges would inevitably be produced at the convex and concave corner portions to ruin the sharpness of the outlines of these corner portions, lowering the print quality.

[0015] The object of this invention is to provide a type which has an integral printing surface and is adapted for use in typewriters, daisy-wheel printers, etc., capable of minimizing the possibility of production of the aforementioned undesired dull print edges, to permit a sharply outlined print of improved quality.

[0016] In order to achieve the above object, a type according to this invention is provided with dull print edge canceling edge means formed at each corner portion of the printing surface of the type where two adjacent edge lines meet so that the edge means is continuous with the adjacent edge lines, whereby a dull print edge at the corner portion is canceled for a sharp print outline.

[0017] The dull print edge canceling edge means preferably includes a joint edge forming an angle narrower than the angle formed between the adjacent edge lines. Thus, the dull print edge is canceled by the sharpness of the joint edge, so that a sharp print outline can be obtained at the corner portion.

[0018] Preferably, the joint edge at the convex corner portion is formed of a projection tapered outwardly from the corner portion, and the joint edge at the concave corner portion is formed of a notch tapered inwardly from the corner portion.

[0019] In a further preferred arrangement, the joint edge formed of the notch is a smooth, U-shaped edge, which can prevent lowering of the strength of molding dies or lowering of the strength of the type due to undesirable effects of the notch.

[0020] These and other objects of this invention will become more apparent and will be better understood with reference to the following detailed description taken in conjunction with the accompanying drawings, in which:

Figs. 1 and 2 are partial enlarged views showing the printing surfaces of prior art types and printed characters reproduced thereby;

Fig. 3 is an enlarged sectional view showing a principal part of a prior art type together with a printing medium and a printing sheet;

Fig. 4 is a diagram for illustrating the way dull print edges are produced;

Fig. 5 is an enlarged side view showing a principal part of a type according to this invention along with a printing medium and a printing sheet;

Figs. 6 and 7 are enlarged views each showing a principal part of the printing surface of the type of the invention, for illustrating the fundamental construction of the type;

Figs. 8(a), 9(a), 10(a), 11(a), 12(a) and 13(a) are enlarged views showing the shapes of printed characters formed by means of various types of the invention; and

Figs. 8(b), 9(b), 10 (b), 11(b), 12(b) and 13(b) are sectional views, as taken along near-surface line I-I of Fig. 5, showing the shapes of printing surfaces corresponding to the printed characters of Figs. 8(a) to 13(a), respectively.

[0021] The construction of types according to this invention will be described in detail with reference to the accompanying drawings of Figs. 5 to 13.

[0022] In Fig. 5, a type 10 of the invention has a body 11, a printing surface 14 protruding from a shoulder 12 of the body 11, and a beard 13 defined between the printing surface 14 and the shoulder 12. The profile of the type 10 shown in Fig. 5 is not expressly different from that of a conventional type.

[0023] The printing surface 14 of the type 10 forms a character, such as a letter, figure, sign, etc. When it is caused to impact against a printing sheet (p) with a transfer medium (r) between them, the printing surface 14 produces a printed character.

[0024] Referring now to Figs. 6 and 7, the fundamental arrangement of the printing surface 14 according to this invention will be described. As shown in the partial enlarged view of Fig. 6, a sharp, outwardly projecting joint edge 16 is formed at a convex corner portion (x) where two adjacent outer edge lines 15 defining an outside contour of the printing surface 14 meet or cross each other, the joint edge 16 being continuous with the edge lines 15. The joint edge 16 is composed of an outwardly tapered projection 17 which is formed integrally with the printing surface 14 at the convex corner portion (x). The angle of the joint edge 16 is adjusted to about 35 to 60 degrees, which is narrower than the angle a defined between the two edge lines 15.

[0025] The projecting joint edge 16 includes two somewhat concavely curved edge line portions which extend outward and meet to form a pointed end. In order to avoid causing a dull print edge at the convex corner portion (x), the shape and size of the joint edge 16 are identical with the desired ones which are determined in consideration of the arcuate isobaric lines (1) at the corner portion (a) as described with reference to Fig. 4.

[0026] As shown in the partial enlarged view of Fig. 7, on the other hand, an inwardly extending joint edge 19 is formed at a concave corner portion (y) where two adjacent inner edge lines 18 defining an inside contour of the printing surface 14 meet or cross each other, the joint edge 19 being continuous with the edge lines 18. The joint edge 19 is composed of a notch 20 tapered toward the inner part of the printing surface 14. The angle β of the joint edge 19 is preferably adjusted to zero to about 10 degrees, which is much narrower than the angle a defined between the two edge lines 15. If β = 0, for example, the width of the notch 20 practically is expected to be 0.1 mm or a little narrower than 0.1 mm.

[0027] Preferably, the notch 20 defined by the joint edge 19 is shaped like a smooth, continuous U-shaped cut, as shown in Fig. 7, in order to prevent lowering of the strength of dies used in forming the notch portion integrally with the printing surface 14, or lowering of the strength of the type due to undesirable effects of the notch 20.

[0028] In order to avoid causing a dull print edge at the concave corner portion (y), the shape and size of the notch 20 are determined in consideration of the isobaric lines (1) at the corner portion (b) as described with reference to Fig. 4.

[0029] Thus, dull print edges at the corner portions (x) and (y) of printed characters can be canceled by providing the convex and concave joint edges 16 and 19 at the convex and concave corner portions (x) and (y), respectively. In other words, the joint edges 16 and 19 serve to compensate for or eliminate a deficiency or excess of printing pressure at the corner portions (x) and (y).

[0030] Thus, the joint edges 16 and 19 constitute dull print edge canceling edge means.

[0031] An experiment conducted by the inventor hereof revealed that the convex and concave joint edges 16 and 19 are particularly effective if they are provided at those corner portions where the angle a between the adjacent edge lines 15 or 18 is an acute angle, i.e., narrower than 90 degrees. It was also found that if the angle a becomes wider, then the possibility of dull print edges being produced at the corner portions is reduced in proportion.

[0032] Figs. 8(a), 9(a), 10(a), 11(a), 12 (a) and 13(a) are enlarged views showing the shapes of various characters 21 printed on printing paper by means of the types 10 of the invention representing various letters A, B, a, b, M and W, respectively. On the other hand, Figs. 8(b), 9(b), 10(b), 11(b), 12(b) and 13(b) are enlarged views showing the shapes of the printing surfaces 14 of the invention used to produce the printed characters 21. Figs. 8(b) to 13(b) are sectional views as taken along near-surface line I-I of Fig. 5, corresponding to the printing surfaces 14. The printing surfaces 14 shown in Figs. 8(b) to 13(b) are each provided with the joint edges 16 and 19 as shown in Figs. 6 and 7 at the corner portions (x) and (y) where dull print edges should expressly be prevented from being produced to ensure sharp outlines. Thus, as shown in Figs. 8(a) to 13(a), the printed characters 21 can enjoy sharp outlines without any dull print edges at the corner portions.

[0033] It is not necessary, however, to provide the joint edges 16 and 19 at all the corner portions of the printing surface 14. The joint edges 16 and 19 are not formed at concave corner portions (z) (Fig. 8(b)) and convex corner portions (f) (Figs. 10(b), 12(b) and 13(b)), for example, since the shape or quality of the printed characters at these portions is hardly influenced by dull print edges, if any, or that the angle between each two adjacent edge lines at the corner portions is an obtuse angle such that the effect of dull print edges is small. At concave corner portions (y) defining blank portions (k) (Figs. 8(b), 9(b) and 10(b)) surrounded by the printing surface 14, however, the concave joint edges 19 should preferably be provided to make the blank portions (k) clear-cut for improved print shape and quality.

[0034] Based on this conception, the convex and concave joint edges 16 and 19 may be provided at desired convex and concave corner portions, respectively, of other characters, including letters, figures, etc., as well as those illustrative characters described in connection with the above-mentioned embodiment.

[0035] The spirit and scope of the invention should not be limited to any obvious changes or modifications which would occur to those skilled in the art. The invention should be interpreted with respect to the following appended claims.

Claims

1. A type having a body (11) and a printing surface (14) protruding from the body and defined by edge lines (15, 18) so as to form a character,
characterized in that edge means (16, 19) for canceling a dull print edge is formed at each corner portion (x, y) of the printing surface (14) where two adjacent edge lines (15, 18) meet so that the edge means (16, 19) is continuous with the adjacent edge lines (15, 18), whereby the dull print edge at the corner portion (x, y) is canceled.

2. The type according to claim 1, characterized in that said dull print edge canceling edge means (16, 19) includes a joint edge forming an angle (β) narrower than the angle (a) formed between the adjacent edge lines (15, 18).

3. The type according to claim 2, characterized in that said corner portion (x) is a convex corner portion, and said joint edge (16) is formed of a projection (17) tapered outwardly from the corner portion.

4. The type according to claim 2, characterized in that said corner portion (y) is a concave corner portion, and said joint edge (19) is formed of a notch (20) tapered inwardly from the corner portion.

5. The type according to claim 4, characterized in that said joint edge (19) formed of the notch (20) is U-shaped.

6. The type according to claim 1, characterized in that the angle formed between the adjacent edge lines (15, 18) at the corner portion (x, y) where the dull print edge canceling edge means (16, 19) is formed is 90 degrees or less.

Drawing