Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Identified backing or protective layer containing
Reexamination Certificate
1999-12-08
2001-10-02
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Identified backing or protective layer containing
C430S501000, C430S496000, C430S140000, C428S690000, C428S690000, C428S690000
Reexamination Certificate
active
06296996
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a transparent magnetic recording medium in which error in input/output (recording/reading) of the magnetic signal hardly occurs.
BACKGROUND OF THE INVENTION
A magnetic recording layer of a magnetic recording medium, such as an audiotape, a videotape, and a floppy disc, contains a high content (coating amount) of magnetic substance, which results in lack of light-permeability, even though high magnetic output (reading) capability can be attained. Consequently, the magnetic recording layer cannot be applied onto the printing surface of a magnetic card or onto a photographic film. U.S. Pat. No. 5,491,051 describes photographic elements that exhibit excellent magnetic and photographic characteristics, and that are capable of repeated use. A difficulty, however, arises for these photographic elements in that recording and reading of magnetic recording information, such as conditions at the time of development and printing, are not assured, as well as at the time of a repeat usage, incorporated with various information, such as the date of photographing, weather, conditions for illumination, conditions at the time of photographing (e.g. the ratio of reduction to enlargement), the number of leaves for reprinting, an area to be zoomed, and some messages. U.S. Pat. No. 5,807,661 describes photographic elements having a transparent magnetic recording layer which is improved in lubricity and durability. However, the photographic elements were not sufficient for the prevention of head staining and for magnetic input/output capacity.
Further, transparent magnetic layer-related techniques are described in JP-A-4-214217 (“JP-A” means unexamined published Japanese patent application), JP-A-6-161033, U.S. Pat. Nos. 5,496,687, 5,432,050, 5,436,120, and 5,434,037.
In fact, for example, when a magnetic recording medium is used as a photographic element (a photographic light-sensitive material), staining materials (processing deposits), which are, for example, composed of substances resulting from dryness of processing solutions in development, thickly adhere to a magnetic head, and thereby contact between the magnetic head and a magnetic layer is extremely deteriorated, which results in a so-called spacing loss. Further consequently, an error in reading of magnetic records from the magnetic recording medium easily arises. In order to clean up the stained head, abrasives are usually added to a magnetic layer. However, use of the abrasives in the manner hitherto known was not sufficient to prevent or remove the staining materials, which are composed of substances resulting from dryness of processing solutions in development, etc., from adhesion or transfer to the magnetic head. Further, when the amount of the abrasives to be added is too much, or the grain size of the abrasives is too large, a new problem arises that the transparency of the medium is too deteriorated for preferable use for photography, or the expected life span of the magnetic head is shortened. In view of the above, there is a need for the development of substantially transparent magnetic recording media that are assuredly capable of recording and reproducing magnetic information, with little occurrence of the above-mentioned problems.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an excellent transparent magnetic recording medium that is assuredly capable of recording and reproducing various magnetic information, with little occurrence of magnetic error, even though the coating amount of the magnetic substance is reduced in order to ensure transparency thereof.
Other and further objects, features, and advantages of the invention will appear more fully from the following description.
DETAILED DESCRIPTION OF THE INVENTION
The above-mentioned object of the invention is attained by a magnetic recording medium having at least one magnetic recording layer containing magnetic particles on a support, which medium comprises protuberances having a height of 0.001 &mgr;m or more than 0.001 &mgr;m, but less than 0.1 &mgr;m, with their density being from 1×10
2
pieces/100 &mgr;m
2
to 1×10
5
pieces/100 &mgr;m
2
, and also other protuberances having a height of from 0.1 &mgr;m to 0.5 &mgr;m, with their density being from 1 piece/100 &mgr;m
2
to 200 pieces/100 &mgr;m
2
, on a magnetic recording medium surface at the side of the at least one magnetic recording layer; and by a silver halide photographic light-sensitive material comprising the above-described transparent magnetic recording layer.
Further, the object of the present invention is also attained by a transparent magnetic recording medium that has, on a support, at least one magnetic recording layer containing magnetic particles,
wherein the medium comprising
a first set of protuberances having a height of 0.001&mgr;m or more than 0.001 &mgr;m, but less than 0.1 &mgr;m, and a density of from 1×10
2
pieces/100 &mgr;m
2
to 1×10
5
pieces/100 &mgr;m
2
, and
a second set of protuberances having a height of from 0.1 &mgr;m to 0.5 &mgr;m, and a density of from 1 piece/100 &mgr;m
2
to 200 pieces/100 &mgr;m
2
,
on a magnetic recording medium surface that is at the side of said at least one magnetic recording layer provided, wherein the difference of height between the first set of protuberances and the second set of protuberances is 0.1 &mgr;m or more but 1.0 &mgr;m or less; and
said medium containing
at least first and second kinds of inorganic particles and/or organic high-molecular particles, each of which has different average primary particle diameter,
in at least the magnetic recording layer or an outer layer positioned such that the magnetic recording layer lies between said outer layer and said support,
and the average primary particle diameter of the first kind of the inorganic particles and/or organic high-molecular particles used to obtain the second set of protuberances is more than 0.4 &mgr;m, but 1.5 &mgr;m or less.
Now, the present invention is described in detail.
Ingredients in processing solutions in development are divided, at the time of drying, by the protuberances having a height of 0.001 &mgr;m or more than 0.001 &mgr;m, but less than 0.1 &mgr;m, with their density being from 1×10
2
pieces/100 &mgr;m
2
to 1×10
5
pieces/100 &mgr;m
2
(hereinafter, the protuberances may be referred to as “shorter (or small) protuberances.”), for use in the present invention, and then the dried solid materials of the ingredients are finely divided. After that, the resultant finely divided stains from processing solutions are hardly adhered to a magnetic head, owing to the protuberances having a height of from 0.1 &mgr;m to 0.5 &mgr;m, with their density being from 1 piece/100 &mgr;m
2
to 200 pieces/100 &mgr;m
2
(hereinafter, the protuberances may be referred to as “taller (or large) protuberances.”), which results in substantially no magnetic error.
The density of the protuberances having a height of 0.001 &mgr;m or more than 0.001 &mgr;m, but less than 0.1 &mgr;m, according to the present invention, is preferably 100 pieces/100 &mgr;m
2
or more, and particularly preferably 500 pieces/100 &mgr;m
2
or more. The upper limit of the number of these protuberances is substantially about 1×10
5
/100 &mgr;m
2
.
Further, the density of the protuberances having a height of from 0.1 &mgr;m to 0.5 &mgr;m is from 1 piece/100 &mgr;m
2
to 200 pieces/100 &mgr;m
2
, preferably from 5 pieces/100 &mgr;m
2
to 100 pieces/100 &mgr;m
2
, and particularly preferably from 7 pieces/100 &mgr;m
2
to 70 pieces/100 &mgr;m
2
.
In order to further reduce head stain, and thereby to reduce magnetic error, it is preferable to regulate the height of the protuberances, so that a difference in height between the taller protuberances and the shorter protuberances is about 0.05 &mgr;m or more, preferably from 0.1 &mgr;m to 1.0 &mgr;m, more preferably from 0.3 &mgr;m to 1.0 &mgr;m, and particularly preferably from 0.5 &mgr;m to 1.0 &mgr;m.
In the transparent magnetic recording m
Matsunaga Naohiro
Ogawa Hiroshi
Burns Doane , Swecker, Mathis LLP
Fuji Photo Film Co. , Ltd.
Letscher Geraldine
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