Thermal developing photosensitive member and image forming method using the thermal developing photosensitive member

A heat developing photosensitive member including: a photosensitive layer containing at least an organic silver salt, a reducing agent and a photosensitive silver halide or a photosensitive silver halide forming agent; and a supporting member for supporting the photosensitive layer thereon, wherein merocyanine dye having a structure in which a thiazole nucleus or selenazole nucleus and hydantoin nucleus, thiohydantoin nucleus or selenohydantoin nucleus are combined with each other by a combining group having a methine group is contained in the photosensitive layer.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a thermal developing photosensitive member 
capable of forming an image by a dry process and an image forming method 
using the thermal developing photosensitive member. 
2. Description of the Prior Art 
A sliver-salt photographing method using a silver halide is a recording 
technology exhibiting excellent sensitivity and gradient expression 
characteristics and therefore used widely. However, the method involving 
to perform the process after exposing the image to light in a wet manner 
has suffered from unsatisfactory working property, convenience and safety. 
On the other hand, a study of dry material, by which the wet process can be 
omitted, has been made and resulted in disclosures in Japanese Patent 
Publication No. 43-4921 and Japanese Patent Publication No. 43-4924. The 
foregoing disclosure each uses a photosensitive silver halide in a 
quantity as a catalyst and a non-photosensitive organic silver salt is 
used as an image forming material. The reason why the organic silver salt 
serves as the image forming material is considered to be due to the 
following mechanism. 
(1) Exposure to an image causes a latent image to be formed on the 
photosensitive silver halide in a quantity which acts as a catalyst; and 
(2) The latent image serves as a catalyst and the photosensitive member is 
therefore heated, causing the organic silver salt and a reducing agent to 
take part in redox reactions to reduce the organic silver salt into silver 
which forms the image. 
The heat developing photosensitive member has an advantage that it forms an 
image by a dry process in place of the wet process. Therefore, it has been 
used as an industrial photosensitive member in a variety of fields, for 
example, image communication, medical care and computer output fields. The 
heat developing photosensitive member exhibits excellent photosensitivity 
because the silver halide is contained as the photosensitive element. 
Furthermore, sensitization to a visible region can easily be performed. 
Recently, a semiconductor laser has been developed and utilized which 
exhibits low cost, small size, light weight and excellent output 
efficiency as compared with a gas laser. Therefore, use of the low-cost, 
small and light laser beam source and the heat developing photosensitive 
member will enable a low-cost, compact and high performance dry image 
recording system to be realized. 
A conventional gelatin-type silver halide photosensitive member for a wet 
process has employed a cyanine dye for the purpose of improving the 
photosensitivity with respect of long wave light, particularly, red light. 
However, the cyanine dye suffers excessively unsatisfactory sensitizing 
efficiency with respect to the heat developing photosensitive member for 
the dry process and therefore it has been considered to be inadequate for 
the foregoing use. 
Although the silver halide photosensitive member for the wet process is 
able to decolor a sensitizing dye by the wet process, the conventional 
heat developing photosensitive member cannot decolor it sufficiently in a 
heating process and therefore raises a problem in that an image having a 
lower optical density cannot easily be obtained. If the sensitizing dye is 
decreased in quantity in order to lower optical density, problems of 
unsatisfactory photosensitivity and defective resolution arise. 
The conventional heat developing photosensitive member has another problem 
in that the photosensitivity deteriorates excessively if it is stored in 
an unused manner for a long time. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a heat developing 
photosensitive member and an image forming method using the heat 
developing photosensitive member with which a compact and economical image 
system can be constituted. Because the heat developing photosensitive 
member is utilized by a semiconductor laser or an LED or the like having 
an oscillation wavelength in a red or near infrared ray region, fog can 
substantially be prevented and excellent storing characteristics can be 
realized. 
According to one aspect of the present invention, there is provided a heat 
developing photosensitive member comprising: a photosensitive layer 
containing at least an organic silver salt, a reducing agent and a 
photosensitive silver halide or a photosensitive silver halide forming 
agent; and a supporting member for supporting the photosensitive layer 
thereon, wherein a merocyanine dye having a structure in which a thiazole 
nucleus or selenazole nucleus and hydantoin nucleus, thiohydantoin nucleus 
or selenohydantoin nucleus are combined with each other by a combining 
group having a methine group is contained in the photosensitive layer. 
According to another aspect of the present invention, there is provided a 
heat developing photosensitive member comprising: a photosensitive layer 
containing at least an organic silver salt, a reducing agent and a 
photosensitive silver halide or a photosensitive silver halide forming 
agent; and a supporting member for supporting the photosensitive layer 
thereon, wherein a merocyanine dye having a structure in which oxazole 
nucleus, thiazole nucleus or selenazole nucleus and 
hydantoinilidene-hydantoin nucleus having four substituents, 
hydantoinilidene-thiohydantoin nucleus having four substituents or 
hydantoinilidene-selinohydantoin nucleus having four substituents are 
combined with each other by a combining group having a methine group is 
contained in the photosensitive layer. 
According to another aspect of the present invention, there is provided a 
heat developing photosensitive member comprising: a photosensitive layer 
containing at least an organic silver salt, a reducing agent and a 
photosensitive silver halide or a photosensitive silver halide forming 
agent; and a supporting member for supporting the photosensitive layer 
thereon, wherein two oxazole nuclei, two thiazole nuclei, or oxazole 
nucleus and thiazole nucleus at two ends thereof and further comprising, 
between the nuclei at the two ends, one nucleus selected from a group 
consisting of oxazolidone nucleus, thiazolidone nucleus and 
dihydroimidazolidone nucleus is contained in the photosensitive layer. 
According to another aspect of the present invention, there is provided an 
image forming method having an arrangement that an image is exposed to a 
heat developing photosensitive member and heating is performed to form an 
image. 
Other and further objects, features and advantages of the invention will be 
appear more fully from the following description. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A heat developing photosensitive member according to the present invention 
comprises, on a supporting member thereof, a photosensitive layer 
containing at least an organic silver salt, a reducing agent, a 
photosensitive silver halide or a photosensitive silver halide forming 
agent, and a sensitizing dye. 
The sensitizing dye for use in the present invention is as follows. 
Sensitizing Agent (a): merocyanine dye having a structure in which a 
thiazole nucleus or selenazole nucleus and hydantoin nucleus, 
thiohydantoin nucleus or selenohydantoin nucleus are combined with each 
other by a combining group having a methine group. 
Sensitizing Agent (b): merocyanine dye having a structure in which oxazole 
nucleus, thiazole nucleus or selenazole nucleus and 
hydantoinilidene-hydantoin nucleus having four substituents, 
hydantoinilidene-thiohydantoin nucleus having four substituents or 
hydantoinilidene-selinohydantoin nucleus having four substituents are 
combined with each other by a combining group having a methine group. 
Sensitizing Agent (c): merocyanine dye having a structure comprising two 
oxazole nuclei, two thiazole nuclei, or oxazole nucleus and thiazole 
nucleus at two ends thereof and further comprising, between the nuclei at 
the two ends, one nucleus selected from a group consisting of oxazolidone 
nucleus, thiazolidone nucleus and dihydroimidazolidone nucleus. 
Use of any one of the foregoing sensitizing dyes (a), (b) and (c) enables 
excellent photosensitivity with respect to red or near infrared region 
light, particularly, light having a wavelength 640 nm to 750 nm. 
Furthermore, the fog density can be lowered. 
The sensitizing agent (a) will now be described. 
As the thiazole nucleus, it is preferable that aromatic thiazole nucleus be 
employed. In particular, it is preferable that benzothiazole nucleus or 
naphthothiazole be employed. In particular, it is preferable that 
naphthothiazole be employed. 
As the selenazole nucleus, it is preferable that aromatic selenazole 
nucleus be employed. In particular, benzoselenazole nucleus or 
naphthoselenazole nucleus be employed. It is most preferable that 
naphthoselenazole be employed. 
Among hydantoin nucleus, thiohydantoin nucleus and selenohydantoin nucleus, 
it is preferable that thiohydantoin nucleus or selenohydantoin nucleus be 
employed. In particular, it is preferable that thiohydantoin nucleus be 
employed. 
It is preferable that the number of methines in the combining group be 2 to 
8, more preferably 4 to 6. The methine chain may have a substituent. 
As the sensitizing dye (a) , it is preferable that substance expressed by 
the following general formula (I) be employed. 
##STR1## 
where r.sup.1, r.sup.2, r.sup.3 and r.sup.4 respectively are hydrogen 
atom, halogen atom, alkyl group, alkoxy group, alkenyl group, aralkyl 
group, hydroxyl group, aryl group, carboxylic group, alkoxycarbonyl group, 
cyano group, trifluoromethyl group, amino group, acylamide group, acyl 
group, acyloxyl group, alkoxycarbonylamino group or carboalkoxy group, r 
and r.sup.2, r.sup.2 and r.sup.3 or r.sup.3 and r.sup.4 may combined with 
each other to form a five or six-membered ring, r.sup.5, r.sup.6 and 
r.sup.7 respectively are alkyl group, alkenyl group, aryl group or aralkyl 
group, r.sup.8, r.sup.9, r.sup.10 and r.sup.11 respectively are hydrogen 
atom, halogen atom, alkyl group, alkoxy group, aryl group or amino group, 
r.sup.8 and r.sup.9, r.sup.10 and r.sup.11, r.sup.8 and r.sup.10 or 
r.sup.9 and r.sup.11 may be combined with each other to form a ring, 
X.sup.1 is sulfur atom or selene atom, X.sup.2 is oxygen atom, sulfur atom 
or selene atom, m.sup.1 and n.sup.2 are each an integer 0 to 3 that are 
not zero simultaneously, r.sup.1 to r.sup.11 may have a substituent or 
not, it is preferable that X.sup.1 and X.sup.2 be sulfur atoms, it is 
preferable that each of r .sup.1 to r.sup.4 be hydrogen atom, halogen 
atom, alkyl group, alkenyl group, aryl group or aralkyl group, in 
particular, it is preferable that r.sup.1 and r.sup.2 or r.sup.3 and 
r.sup.4 be combined with each other to form a naphthonucleus, the 
naphthonucleus may be substituted with an alkyl group or a halogen atom, 
it is preferable that each of r.sup.5 to r.sup.7 be an alkyl group, it is 
preferable that r.sup.8 to r.sup.11 be hydrogen or alkyl group, and 
m.sup.1 and n.sup.1 be integers holding a relationship m.sup.1 +n.sup.1 
=2. 
Preferred examples of the sensitizing dye (a) are as follows: 
##STR2## 
The sensitizing dye (b) will now be described. 
As the oxazole nucleus, it is preferable that aromatic oxazole nucleus be 
employed, more preferably benzoxazole nucleus be employed. 
As the thiazole nucleus, it is preferable that aromatic thiazole nucleus be 
employed, more preferably benzothiazole nucleus be employed. 
As the selenazole nucleus, it is preferable that aromatic selenazole 
nucleus be employed, more preferably benzoselenazole nucleus be employed. 
The hydantoinilidene-hydantoin nucleus having four substituents means 
1,1',3,3'-substituted hydantoinilidene-hydantoin nucleus. The 
hydantoinilidene-thiohydantoin nucleus having four substituents and the 
hydantoinilidene-seleno hydantoin nucleus having four substituents as well 
as mean the same. Among (i) hydantoinilidene-hydantoin nucleus having four 
substituents, (ii) hydantoinilidene-thiohydantoin nucleus having four 
substituents and (iii) hydantoinilidene-selenohydantoin nucleus having 
four substituents, it is preferable that (ii) or (iii) be employed, more 
preferably (ii) be employed. 
It is preferable that the number of methines in the combining group be 2 to 
8, more preferably 4 to 6. The methine chain may have a substituent. 
It is preferable that the sensitizing pigment (b) be a substance expressed 
by the following general formula (II). 
##STR3## 
where r.sup.12, r.sup.13, r.sup.14 and r.sup.15 respectively are hydrogen 
atom, halogen atom, alkyl group, alkoxy group, alkenyl group, aralkyl 
group, hydroxyl group, aryl group, carboxylic group, alkoxycarbonyl group, 
cyano group, trifluoromethyl group, amino group, acylamide group, acyl 
group, acyloxyl group, alkoxycarbonylamino group or carboalkoxy group, 
r.sup.12 and r.sup.13, r.sup.13 and r.sup.14 or r.sup.14 and r.sup.15 may 
combined with each other to form a five or six-membered ring, r.sup.16, 
r.sup.17, r.sup.18, r.sup.19 and r.sup.20 respectively are alkyl group, 
alkenyl group, aryl group or aralkyl group, r.sup.21, r.sup.22, r.sup.23 
and r.sup.24 respectively are hydrogen atom, halogen atom, alkyl group, 
alkoxy group, aryl group or amino group, r and r.sup.22, r.sup.23 and 
r.sup.24, r.sup.21 and r.sup.23 or r.sup.22 and r.sup.24 may be combined 
with each other to form a ring, x.sup.3 and x.sup.4 are oxygen atoms, 
sulfur atoms or selene atoms, m.sup.2 and n.sup.2 are integers 0 to 3 that 
are not zero simultaneously, r.sup.12 to r.sup.24 may have a substituent 
or not, it is preferable that X.sup.3 and X.sup.4 be sulfur atoms, it is 
preferable that each of r.sup.12 to r.sup.15 be hydrogen atom, halogen 
atom, alkyl group, alkenyl group, aryl group or aralkyl group, in 
particular, it is preferable that r.sup.12 and r.sup.13 or r.sup.14 and 
r.sup.15 be combined with each other to form a naphthonucleus, the 
naphthonucleus may be substituted with an alkyl group or a halogen atom, 
it is preferable that each of r.sup.16 to r.sup.20 be an alkyl group, it 
is preferable that r.sup.21 to r.sup.24 be hydrogen or alkyl group, and 
m.sup.2 and n.sup.2 be integers holding a relationship m.sup.2 +n.sup.2 
=2. 
Preferred examples of the sensitizing dye (b) are as follows. 
##STR4## 
The sensitizing dye (c) will now be described. 
As the oxazole nucleus, it is preferable that aromatic oxazole nucleus be 
employed, more preferably benzoxazole nucleus or naphthoxazole nucleus be 
employed. As the thiazole nucleus, it is preferable that aromatic thiazole 
nucleus be employed, more preferably benzoxazole nucleus or naphthoxazole 
nucleus be employed. 
Among oxazolidone nucleus, thiazolidone nucleus and dihydroimidazolidone 
nucleus, it is preferable that oxazolidone nucleus or thiazolidone nucleus 
be employed, more preferably thiazolidone nucleus be employed. 
The sensitizing dye (c) has, in one molecule thereof, two combining groups 
for combining nuclei with each other. It is preferable that the two 
combining groups be combined groups of a type having a methine chain. It 
is preferable that the number of methines of one combining group be 1 to 
5. If the one combining group in one molecule has an even number of 
methines, it is preferable that the number of another combining group has 
an odd number of methines. 
It is preferable that the sensitizing dye (c) has a structure expressed by 
the following general formula (III). 
##STR5## 
where A.sub.1.sup.- is substituted or unsubstituted alkyl sulfonic acid 
ion, substituted or unsubstituted aromatic sulfonic acid ion, 
NO.sub.3.sup.-, Cl.sup.-, Br.sup.-, I.sup.- or ClO.sub.4.sup.-, X.sup.5 is 
substituted or unsubstituted imino group, y.sup.1 and y.sup.2 respectively 
are oxygen atom or sulfur atom, r.sup.31 and r.sup.32 respectively are 
substituted or unsubstituted alkyl group, substituted or unsubstituted 
aryl group or substituted or unsubstituted aralkyl group, Z.sup.1 is 
oxygen atom, sulfur atom, selenium atom or substituted or unsubstituted 
imino group, r.sup.33, r.sup.34, r.sup.35, r.sup.36 and r.sup.37 
respectively are hydrogen atom, halogen atom, substituted or unsubstituted 
alkyl group, alkoxy group, substituted or unsubstituted aryl group or 
substituted or unsubstituted amino group, r.sup.33 and r.sup.34, r.sup.36 
and r.sup.37, r.sup.35, r.sup.36 and r.sup.37 may form a ring, m.sup.3 and 
n.sup.3 are integers 1 to 3, it is preferable that r.sup.31 and r.sup.32 
be alkyl groups, more preferably ethyl groups, it is preferable that 
r.sup.33 to r.sup.37 be hydrogen atoms or alkyl groups, it is preferable 
that m.sup.3 and n.sup.3 be integers holding a relationship m.sup.3 
+n.sup.3 =2 to 4. 
Preferred examples of the sensitizing dye (c) are as follows. 
##STR6## 
As the organic silver salt, an organic silver salt or triazole silver salt 
disclosed in "Basis of Photographic Engineering", 247, chapter "Non-silver 
salt" edited by , Japan Photography Institute and published by Corona 
Corp., Tokyo, No. 1 edition, 1982, or Japanese Patent Laid-Open No. 
59-55429 may be employed. It is preferable that a silver salt having a low 
sensitivity be employed. For example, any one of a silver salt selected 
from the following group may be employed; the group consisting of 
aliphatic carboxylic acid, aromatic carboxylic acid, thiol, thiocarbonyl 
compound having .alpha.-hydrogen or a compound containing an imino group. 
The aliphatic carboxylic acid is exemplified by acetic acid, butyric acid, 
succinic acid, sebacic acid, adipic acid, oleic acid, linolic acid, 
linolenic acid, tartaric acid, palmitic acid, stearic acid, behenic acid 
and camphoric acid. Since the silver salt is generally instable if the 
number of carbon atoms decreases, it is preferable that a compound having 
an adequate number of carbon atoms (for example, 16 to 26 carbon atoms) be 
employed. 
The aromatic carboxylic acid is exemplified by benzoic acid derivative, 
quinolinic acid derivative, naphthalene carboxylic acid derivative, 
salicylic acid derivative, gallic acid derivative, tannic acid, phthalic 
acid, phenylacetic acid derivative and pyromellitic acid. 
The thiol or thiocarbonyl compound having .alpha.-hydrogen is exemplified 
by dithiocarboxylic acids such as 3-mercapto-4-phenyl-1,2,4-triazole, 
2-mercapto-4-phenyl,1,2,4-triazole, 2-mercaptobenzoimidazole, 
2-mercapto-5-aminothiadiazole, 2-mercaptobenzothiazole, S-alkylthioglycol 
acid (the alkyl group having 12 to 23 carbon atoms), and dithioacetic 
acid, thioamido such as thiostearoamide, and mercapto compounds disclosed 
in U.S. Pat. No. 4,123,274, such as 
5-carboxy-1-methyl-2-phenyl-4-thiopyridone, mercaptotriazine, 
2-mercaptobenzoxazole, mercaptoxathiazole or 
3-amino-5-benzylthio-1,2,4-triazole. 
The compound having an imino group is exemplified by benzotriazole or its 
derivative disclosed in Japanese Patent Publication No. 44-30270 or 
Japanese Patent Publication No. 45-18416, for example, an alkyl 
substituted benzotriazole such as benzotriazole or methylbenzotriazole, a 
halogen substituted benzotriazole such as 5-chlorobenzotriazole, a 
carboimidobenzotriazole such as butyl carboimidobenzotriazole, 
nitrobenzotriazole disclosed in Japanese Patent Laid-Open No. 58-118639, 
sulfobenzotriazole, carboxybenzotriazole or their salts or 
hydroxybenzotriazole disclosed in Japanese Patent Laid-Open No. 58-115638, 
and 1,2,4-triazole, 1H-tetrazole, carbazole, saccharin, imidazole and 
their derivatives disclosed in U.S. Pat. No. 4,220,709. 
As the reducing agent, all materials (preferably organic materially) of a 
type capable of reducing silver ions into a metal silver may be employed. 
The reducing agent is exemplified by monophenol, bisphenol, trisphenol, 
tetrakisphenol, mononaphthol, bisnaphthol, dihydroxynaphthalene, 
sulfonamidophenol, biphenol, trihydroxynaphthalene, dihydroxybenzene, 
trihydroxybenzene, tetrahydroxybenzene, hydroxyalkylmonoether, ascorbic 
acid, 3-pyrazolidone, pyrazolone, pyrazoline, sugars, phenylenediamine, 
hydroxyamine, reductone, hydroxamine, hydrazine, hydrazido, amidoxime, and 
N-hydroxyurea. Among the foregoing substance, it is preferable that 
p-bisphenol, o-bisphenol, bisnaphthol or 4-substituted naphthol be 
employed. A reducing agent disclosed in Japanese Patent Laid-Open No. 
3-135564 may be employed. 
The photosensitive silver halide is exemplified by silver chloride, sliver 
bromide, silver chlorobromide, silver bromoiodide and silver 
chlorobromoiodide. 
As a method of preparing the silver halide, a method in which a portion of 
an organic silver salt is halogenated by a photosensitive silver halide 
forming component, such as ammonium bromide, lithium bromide, sodium 
chloride or N-bromo succinimide imide to prepare the silver halide and a 
method a so-called system-outside silver halide is contained are 
exemplified. 
The shape of crystal of the silver halide is exemplified by a cubic shape, 
octahedral shape and flat shape. It is preferable that the cubic or flat 
shape be employed. A preferred length of one side of crystal of the cubic 
silver halide is 0.01 to 2 .mu.m, more preferably 0.02 to 0.5 .mu.m. It is 
preferable that the mean aspect ratio of the flat silver halide be 100:1 
to 3:1, more preferably 50:1 to 5:1. It is preferable that the diameter of 
its particle be 0.01 to 2 .mu.m, more preferably 0.02 to 0.5 .mu.m. 
The silver halide may contain iridium ions in the surface layer of the 
crystal thereof. The "surface layer of the crystal" is a layer having a 
predetermined depth from the surface of the crystal. It is preferable that 
the shape of the silver halide crystal be a tetragon having planes (1,0,0) 
. It is preferable that the thickness of the surface layer of the crystal 
containing iridium ions be 10% or less of the length of the one side of 
the crystal, more preferably 5% or less. It is preferable that the surface 
layer of the crystal containing iridium ions be 0.5 % or longer than the 
length of one side of the crystal. 
The silver halide containing iridium ions can be prepared by injecting a 
member for supplying iridium ions when the silver halide is obtained from 
an irreducible organic silver salt and a component for forming the silver 
halide. It is preferable that the member for supplying iridium ions be 
iridium tetrachloride, iridium hexachloride (IV) potassium or iridium 
hexachloride (IV) sodium. 
Iridium ions can be contained in the surface layer of silver halide crystal 
by injecting the member for supplying iridium ions after a short time has 
passed from the commencement of the generation of the silver halide. For 
example, the injection of the member for supplying iridium ions may be 
commenced at a moment 90 wt % of a predetermined quantity of the silver 
halide is generated. 
Although the overall portion of the silver halide according to the present 
invention may contain iridium ions, a mixture of a silver halide 
containing iridium ions and a silver halide containing no iridium ions may 
be employed. 
It is preferable that the content of iridium ions be 1.times.10.sup.-8 mole 
to 1.times.10.sup.-4 mole with respect to 1 mole of silver halide, more 
preferably 1.times.10.sup.-7 to 1.times.10.sup.-6 mole. 
The heat developing photosensitive member according to the present 
invention may contain cyanine dye expressed by general formula (IV). 
Employing the cyanine dye expressed by general formula (IV) improves the 
storing characteristics in an unused state and the resolution. 
##STR7## 
where r.sup.41, r.sup.42, r.sup.43, r.sup.44, r.sup.47, r.sup.48, 
r.sup.49, r.sup.49 and r.sup.50 respectively are hydrogen atom, halogen 
atom, alkyl group, alkoxy group, aryl group or amino group, r.sup.41 and 
r.sup.42, r.sup.42 and r.sup.43, r.sup.43 and r.sup.44, r.sup.47 and 
r.sup.48, r.sup.49 and r.sup.49 or r.sup.49 and r.sup.50 may be combined 
with each other to form a ring, r.sup.51, r.sup.52, r.sup.53, r.sup.54 and 
r.sup.55 respectively are hydrogen atom, alkyl group or aryl group, 
r.sup.51 and r.sup.53, r.sup.52 and r.sup.54, and r.sup.53 and r.sup.55 
may be combined with each other to form a ring, r.sup.45 and r.sup.46 
respectively are alkyl group or aralkyl group, Y.sup.3 and Y.sup.4 
respectively are oxygen atom, sulfur atom, carbon atom or nitrogen atom, 
if the they are carbon atoms or nitrogen atoms any one of hydrogen atom, 
alkyl group, aryl group or aralkyl group is combined, A.sup.-.sub.2 is an 
anion, m.sup.4 and n.sup.4 respectively are 0, 1 or 2, it is preferable 
that A.sup.-.sub.2 be bromine, iodine, chlorine, perchloric acid, 
tetrafluoroborate, toluenesulfonate or arsenic hexafluoride, it is 
preferable that Y.sup.3 and Y.sup.4 respectively be oxygen atoms or 
nitrogen atoms, if r.sup.45 and r.sup.46 each have an anion such as 
carboxylic alkyl group or sulfonic acid alkyl A.sup.-.sub.2 is not 
sometimes present, it is preferable that m.sup.4 and n.sup.4 are not zero 
simultaneously, and it is preferable that m.sup.4 +n.sup.4 be 2 . 
Preferred examples of the cyanine dye expressed by general formula (IV) are 
as follows. 
##STR8## 
It is preferable that an adequate binder be contained in the photosensitive 
layer. The binder of the component (d) is exemplified by:an ester of 
cellulose, such as nitrocellulose, cellulose phosphate, cellulose sulfate, 
cellulose acetate, cellulose propionate, cellulose butyrate, cellulose 
myristate, cellulose palmitate, cellulose acetate propionate or cellulose 
acetate butyrate; an ether of cellulose, such as methyl cellulose, ethyl 
cellulose, propyl cellulose or butyl cellulose; a vinyl polymer, such as 
polystyrene, polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, 
polyvinyl acetal, polyvinylalcohol or polyvinyl pyrrolidone; a copolymer 
such as copolymer of styrene and butadiene, copolymer of styrene and 
acrylonitrile, copolymer of styrene, butadiene and acrylonitrile or 
copolymer of vinyl chloride and vinyl acetate; an acryl polymer such as 
polymethylmethacrylate, polymethylacrylonitrile, polybutylacrylate, 
polyacrylic acid, polymethacrylic acid, polyacrylamide or 
polyacrylonitrile; a polyester such as polyethylene terephthalate; a 
polyacrylate polymer such as poly 
(4,4-isopropylidene-diphenylene-co-1,4-cyclohexylenedimethylene 
carbonate), poly (ethylenedioxy-3,3'-phenylenethiocarbonate), poly 
(4,4'-isopropylidenediphenylene carbonate-co-terephthalate), poly 
(4,4'-isopropylidenediphenylene carbonate), polyamide, poly 
(4,4'-sec-butylidenephenylene carbonate) or poly 
(4,4'-isopropylidenediphenylene carbonate-block-oxyethylene); a polyimide; 
an epoxy polymer; a phenol polymer; a polyolefin such as polyethylene, 
polypropylene or chlorinated polyethylene; and natural resin such as 
gelatin or synthetic resin. In particular, it is preferable that polyvinyl 
acetal such as polyvinyl butyral or polyvinyl formal or vinyl copolymer 
such as vinyl chloride acetate vinyl copolymer be employed. 
The heat developing photosensitive member according to the present 
invention may contain a thiol compound expressed by the following general 
formula (V) or (VI). The heat developing photosensitive member according 
to the present invention may contained both thiol compounds respectively 
expressed by the following general formulas (V) and (VI). The contained 
thiol compound improves the sensitivity and the stoking characteristics in 
an unused state. Furthermore, the temperature control required in the heat 
developing process can be moderated (that is, the heat developing latitude 
can be widened). 
##STR9## 
where R.sup.1 to R.sup.10 respectively are hydrogen atom, substituted or 
unsubstituted alkyl group, substituted or unsubstituted alkoxy group or 
carboxylic group, substituted or unsubstituted aryl group or sulfonic acid 
group, substituted or unsubstituted amino group, nitro group, halogen 
atom, amido group, alkenyl group or alkenyl group R.sup.1 and R.sup.2, 
R.sup.2 and R.sup.3, and R.sup.3 and R.sup.4 respectively may form a 
contraction ring, X.sup.10 and X.sup.11 respectively are --O--, --N 
(R11)-- or --S--, R.sup.11 is hydrogen, alkyl group or aryl group. 
Preferred examples of the thiol compound expressed by general formula (V) 
or (VI) are as follows: 
##STR10## 
The photosensitive member according to the present invention may contain a 
color-tone adjuster if necessary. The color-tone adjuster is exemplified 
by phthalazinone or its derivatives disclosed in U.S. Pat. No. 3,080,254, 
a circular imide disclosed in Japanese Patent Laid-Open No. 46-6074 and a 
phthalazinone compound disclosed in Japanese Patent Laid-Open No. 
50-32927. 
The photosensitive member according to the present invention may contain an 
organic acid if necessary to improve the color tone of a formed image and 
stability after the image has been formed. In particular, it is preferable 
that a long-chain fatty acid be contained solely or in a combined manner. 
The heat developing photosensitive member according to the present 
invention contains the components mixed at the following mixture ratio: 
It is preferable that the content of the organic silver salt be 5 to 70 wt 
% of the photosensitive layer, more preferably 20 to 50 wt %. Even if the 
photosensitive layer is in the form of a multi-layer as described later, 
the content of the organic silver salt is contained in a quantity as 
described above with respect to the overall photosensitive layer. 
It is preferable that the content of the reducing agent be 0.05 to 3 moles 
with respect to one mole of the organic silver salt, more preferably 0.2 
to 2 moles. 
It is preferable that 0.001 to 2 moles, preferably 0.05 moles to 1 mole 
photosensitive silver halide be contained with respect to one mole of 
organic silver salt. In the present invention, a silver halide forming 
agent, such as tetrabutyl ammonium bromide, N-bromosuccinimide or a 
halogen compound of bromide or iodine may be contained in place of the 
silver halide. In this case, the content of the silver halide forming 
agent may be determined similarly to the case of the silver halide. 
It is preferable that the sensitizing dye expressed by any one of the 
general formula (I) to (III) be 1.times.10.sup.-5 to 1.times.10.sup.-2 
moles with respect to one mole of the organic silver salt, more preferably 
10.sup.-4 to 1.times.10.sup.-3 moles. 
It is preferable that the content of the cyanine dye contained if necessary 
and expressed by general formula (IV) be 1.times.10.sup.-5 to 
1.times.10.sup.-2 moles, more preferably 1.times.10.sup.-4 to 
1.times.10.sup.-3 moles with respect to one mole of the organic silver 
salt. 
It is preferable that the content of the thiol compound contained if 
necessary and expressed by general formula (V) or (VI) be 
1.0.times.10.sup.-1 to 2.0.times.10.sup.2 moles, more preferably 
5.0.times.10.sup.-1 to 1.0.times.10.sup.2 moles, and most preferably 1.0 
to 8.0.times.10 moles with respect to one mole of the sensitizing pigment 
by general formula (I) to (III). 
It is preferable that the content of the binder contained if necessary be 
0.5 to 10 parts by weight with respect to 1 part by weight of the organic 
silver salt, more preferably 0.5 to 5 parts by weight. 
It is preferable that the organic acid contained if necessary be 25 mol % 
to 200 mol % with respect to the organic silver salt, more preferably 30 
mol % to 120 mol %. 
It is preferable that the content of the color-tone adjuster contained if 
necessary be 0.01 to 5 moles, more preferably 0.05 to 2 moles, and most 
preferably 0.08 to 1 mole with respect to one mole of the organic silver 
salt. 
The photosensitive member according to the present invention may contain an 
adequate fog preventive agent. The fog preventive agent is exemplified by 
a mercury compound disclosed in Japanese Patent Publication No. 47-111113, 
1,2,4-triazole compound disclosed in Japanese Patent Publication No. 
55-42375, a tetrazole compound disclosed in Japanese Patent Laid-Open No. 
57-30828, a benzoic acid disclosed in Japanese Patent Laid-Open No. 
57-138630, a compound having a sulfonylthio group disclosed in Japanese 
Patent Laid-Open No. 57-147627 and a dibasic acid disclosed in Japanese 
Patent Laid-Open No. 58-107534. It is preferable that the dibasic acid 
disclosed in Japanese Patent Laid-Open No. 58-107534 be employed. 
The photosensitive member according to the present invention may contain a 
coloring preventive agent, if necessary to prevent coloring of a non-image 
portion due to light after the image has been formed. It is preferable 
that the coloring preventive agent be a compound disclosed in Japanese 
Patent Laid-Open No. 61-129642 for example. 
The photosensitive member according to the present invention may contain a 
development promoting agent, if necessary. A preferred development 
promoting agent is exemplified by an alkali metal salt compound of a fatty 
acid disclosed in Japanese Patent Publication No. 64-8809 for example. 
The photosensitive member according to the present invention may contain a 
surface active agent containing fluorine, if necessary. Both surface 
active agent containing fluorine disclosed in Japanese Patent Laid-Open 
No. 64-24245 and a nonion surface active agent may be contained. 
The photosensitive member according to the present invention may contain an 
ultraviolet-ray absorbing agent, a halation preventive dye (layer) and an 
irradiation preventative dye, if necessary. It may contain a fluorescent 
whitening agent. 
The thermal developing photosensitive member according to the present 
invention can be obtained by forming a single or a plurality of layers 
containing the foregoing components on an adequate supporting member. If 
the photosensitive layer is formed into a multi-layer structure, it is 
preferable that the multi-layer is composed of layers respectively 
containing the organic silver salt, the silver halide and the sensitizing 
dye expressed by general formula (I) to (III) and a layer containing the 
reducing agent. The thio compound contained if necessary and expressed by 
general formula (V) or (VI) is contained in the layer containing the 
sensitizing dye. 
The supporting member may be:a synthetic resin film made of polyethylene, 
polypropylene, polyethylene terephthalate, polycarbonate or cellulose 
acetate; synthetic paper; paper covered with a synthetic resin film such 
as polyethylene; paper such as art paper or barayta paper for photography; 
a metal plate (or foil) made of aluminum; a synthetic resin film having an 
evaporated metal film; or glass. 
In order to improve transparency of the heat developing photosensitive 
member, thickening the density of the formed image, improving the natural 
storing characteristics, and, if necessary, improving the heat resistance 
of the photosensitive member, a protective layer may be formed on the 
photosensitive layer. It is preferable that the thickness of the 
protective layer be 1 .mu.m to 20 .mu.m. If it is thinner than the 
foregoing value, the desired effect cannot be obtained. If it is thicker 
than the same, any particular advantage cannot be obtained while raising 
the cost. A preferred polymer for use in the protective layer has heat 
resistance, and it is colorless and soluble in a solvent. It is 
exemplified by polyvinyl chloride, polyvinyl acetate, a copolymer of vinyl 
chloride and vinyl acetate (preferably vinyl chloride being 50 mol % or 
more), polyvinyl butyral, polystyrene, polymethyl methacrylate, 
benzylcellulose, ethylcellulose, cellulose acetate-butyrate, cellulose 
diacetate, cellulose triacetate, polyvinylidene chloride, chlorinated 
polypropylene, polyvinyl pyrrolidone, cellulose propionate, polyvinyl 
formal, cellulose acetate butyrate, polycarbonate, cellulose acetate 
propionate, gelatin, a gelatin derivative such as phthalic gelatin, 
acrylamidopolymer, polyisobutylene, copolymer of butadiene and styrene (at 
an arbitrary monomer ratio), and polyvinyl alcohol. In addition to the 
foregoing binders, colloidal silica may be contained in the protective 
layer. 
It is preferable that the polymer for the protective layer has heat 
resistance of 115.degree. or higher and a refractive index of 1.45 or 
higher at 20.degree. C. 
In a case where the layers respectively having the functions, such as the 
photosensitive layer and the protective layers are individually formed in 
the heat developing photosensitive member according to the present 
invention, the foregoing layers may be applied by any one of a variety of 
coating methods. The layers can be formed by an air knife method, a 
curtain coating method or an extruding coating method using a hopper as 
disclosed in U.S. Pat. No. 2,681,294. In this case, two or more layers may 
be applied simultaneously. 
The heat developing photosensitive member according to the present 
invention causes the organic silver salt and the reducing agent to take 
part in the reducing reactions in a portion exposed to an image due to the 
image exposure and the applied heat (heat development). Metal silver 
generated due to the reactions form a blackened image. 
The heat developing photosensitive member may use the light absorbance of 
an oxidized member (a material obtained by oxidizing the reducing agent) 
generated due to the redox reactions to form a pattern depending upon the 
difference in the light absorbance. That is, the pattern may be formed 
using the difference in the light absorbance such that light having a 
specific wavelength is absorbed in a portion in which the oxidized 
substance has been generated (the image exposure portion) and light 
absorption is limited in a portion in which no oxidized substance is 
generated (portion omitted from image exposure). 
By using the difference in the light absorbance, the heat developing 
photosensitive member according to the present invention enables a pattern 
to be formed, the pattern being composed of a polymerized portion and a 
non-polymerized portion (hereinafter called a polymerized and 
non-polymerized pattern). That is, a polymerizable polymer precursor and a 
light polymerization initiator are contained in the photosensitive layer 
according to the present invention, and image exposure, heat development 
and polymerizing exposure are caused to undergo so that the polymerized 
and non-polymerized pattern can be formed. The reason why the polymerized 
and non-polymerized pattern can be formed is that silver or oxidized 
substance generated in the image exposure portion due to the oxidation and 
reduction reactions taking part in the heat developing process inhibits 
the polymerization, while the polymerization occurs in the 
non-image-exposure portion. 
Although the polymerizable polymer precursor and the light polymerization 
initiator may be contained in the photosensitive layer, a polymerized 
layer containing the polymerizable polymer precursor and the light 
polymerization initiator may be formed individually from the 
photosensitive layer. 
The photosensitive layer and the polymerized layer may be stacked in an 
order as the polymerized layer and the photosensitive layer from when 
viewed from the supporting member. They may be stacked in an order as the 
photosensitive layer and the polymerized layer when viewed from the 
supporting member. As an alternative to this, the photosensitive layer may 
be formed on either side of the supporting member and the polymerized 
layer may be formed on the other side with the supporting member 
interposed therebetween. 
It is preferable that the thickness of the photosensitive layer be 0.1 
.mu.m to 50 .mu.m, more preferably 1 .mu.m to 30 .mu.m, and most 
preferably 2 .mu.m to 20 .mu.m. In a case where the photosensitive layer 
is formed into a multi-layer structure, each photosensitive layer has 
substantially the same thickness. 
A method of forming an image by using the photosensitive member according 
to the present invention will now be described. 
Since the photosensitive member according to the present invention contains 
the sensitizing agents expressed by general formulas (I) to (III) as 
described above, excellent sensitivity and heat developing characteristics 
while having a sensitivity capable of sensing red and near infrared ray 
region. Therefore, when the photosensitive according to the present 
invention is exposed to image exposure corresponding to a desired image 
with a semiconductor laser beam or LED light, in particular, light of 640 
nm to 750 nm, a silver nucleus is generated and thus a latent image is 
initially formed. Then, heat applied adequately will cause redox reactions 
to take place so that an image corresponding to the image exposure is 
developed. 
The image forming method according to the present invention and capable of 
forming an image as described above can easily be treated in the process 
and adaptable to a mechanical process. Since it is able to use 
semiconductor laser beam or LED light, the size of the system can be made 
to be compact while attaining an economical advantage. The photosensitive 
member according to the present invention is free from the reciprocity 
failure even if a short time image exposing of 1.times.10.sup.-5 sec/dot 
to 1.times.10.sup.-7 sec/dot is performed. 
The heat developing photosensitive member according to the present 
invention containing the polymerizable polymer precursor and the light 
polymerization initiator is able to form the polymerized and 
non-polymerized pattern by performing polymerizing exposure to the entire 
surface of the heat developing photosensitive member from a position 
facing the photosensitive layer after the foregoing image exposure and the 
heat development have been completed. 
The light source for use in the polymerizing exposure process may be 
sunlight, tungsten lamp, mercury lamp, halogen lamp, xenon lamp, 
fluorescent lamp, LED or laser beam. 
The wavelength of the light for the polymerizing exposure may be the same 
as that of the image exposing light or may be another wavelength. 
Since the photosensitive silver halide usually has excellent 
photosensitivity superior to that of the light polymerization initiator 
even if the same wavelength is used, writing of a latent image can be 
performed with light of an intensity of a degree with which light 
polymerization does not undergo in the foregoing image exposure process. 
It is preferable that the exposure be performed with light of 100 
.mu.J/cm.sup.2, more preferably 30 .mu.J/cm.sup.2, and most preferably 15 
.mu.J/cm.sup.2 on the surface of the photosensitive member in the image 
exposure process. It is preferable that exposure be performed with light 
of 500 mJ/cm.sup.2 on the surface of the photosensitive member in the 
polymerizing exposure process. If the polymerizing exposure is not 
performed, the image exposure process is performed under the foregoing 
condition. 
The photosensitive member according to the present invention may be 
developed with heat by any one of a variety of means. For example, the 
photosensitive member may be brought into contact with a simple heating 
plate or the like. It may be brought into contact with a heated drum. It 
may be allowed to pass through a heated space on the situation. It may be 
heated with high frequency waves or laser beams. It is preferable that the 
heating temperature be 80.degree. C. to 160.degree., more preferably 
100.degree. C. to 160.degree. C., and most preferably 110.degree. C. to 
150.degree. C. By lengthening the heating duration or by shortening it, it 
may be used at a further high temperature or a further low temperature 
within the foregoing range. The developing period is usually one to 60 
seconds, preferably 3 to 20 seconds. 
As described above, an image exhibiting excellent quality can be obtained 
while being free from reciprocity failure and a problem of fog even if the 
exposure is performed with a high illuminance applied in a short time by 
means of the laser or the like. Furthermore, the heat developing 
photosensitive member according to the present invention exhibits 
excellent stocking characteristics.

The present invention will now be described further in detail with 
reference to examples. 
EXAMPLE 1 
A photosensitive composition having the following composition was prepared 
with safety light applied to the same. 
______________________________________ 
Polyvinylbutyral 5.0 g 
Silver Behenate 2.5 g 
Behenic Acid 2.0 g 
Silver Bromide 0.2 g 
Phthalazinone 1.0 g 
2,2'-methylene bis (6-t-butyl-4-methylphenol) 
1.0 g 
Xylene 30 ml 
n-butanol 30 ml 
______________________________________ 
The silver bromide is in the form of cubic crystal, the plane index of 
which was {100} and an average length of one side of which was 0.07 .mu.m. 
5 mg of the sensitizing dye (I-7) was dissolved in 5 ml of N,N-dimethyl 
formamide (DMF). The solution thus obtained was added to the foregoing 
photosensitive composition. The composition was applied to the upper 
surface of a polyethylene terephthalate (PET) film to have a dry thickness 
of 10 .mu.m so that a photosensitive layer was formed. Furthermore, a 
protection layer was formed by applying a polyvinyl alcohol layer having a 
dry thickness of 2 .mu.m so that the heat developing photosensitive member 
according to the present invention was obtained. 
The thus-obtained heat developing photosensitive member was subjected to 
evaluations of the sensitivity and the fog density immediately after the 
photosensitive member had been formed, the sensitivity and the fog density 
after it had been stored for a long time without being used. The storage 
conditions were such that it was stored for 72 hours in an environment, 
the temperature of which was 50.degree. C. and the relative humidity of 
which was 80% RH. 
The sensitivity and the fog density were measured in such a way that an 
image was formed on the heat developing photosensitive member and the 
transmitted optical density (O.D) of the formed image was measured. 
That is, the fog density was the transmitted optical density realized when 
the image exposing energy was 0.1 .mu.J/cm.sup.2 The sensitivity was 
defined to be the value of image exposing energy required to realize the 
transmitted optical density which was a value obtained by adding 0.5 to 
the fog density. Therefore, the sensitivity is obtained from the 
characteristics curve of the reflected optical density and the fog density 
with respect to the image exposing energy. 
The transmitted optical density was measured by using a 
transmission/reflection color density meter NLM-STD-Tr (manufactured by 
Narumi). 
The image was formed such that the heat developing photosensitive member 
was exposed to an image with a semiconductor laser, the wavelength of 
which was 670 nm. Then, heat development was performed for 10 seconds in a 
heat developing unit set to 118.degree. C. The diameter of the 
semiconductor laser beam spot was 20 .mu.m.times.40 .mu.m and the exposing 
speed was 1.67.times.10.sup.-7 sec/dot. 
The characteristics curve of the reflected optical density with respect to 
the image exposure energy was made such that images were formed with 
various image exposing energies and the transmitted optical densities of 
the obtained images were measured. 
The obtained sensitivity and the fog density were shown in Table 1. 
Further, the,- resolution of the foregoing heat developing photosensitive 
member was evaluated as follows. 
Initially, the heat developing photosensitive member was exposed to an 
image at resolutions 300 dpi, 600 dpi and 900 dpi by using semiconductor 
laser beams, the wavelength of which was 680 nm. Then, heat development 
was performed for 10 seconds in a heat developing unit set to 120.degree. 
C. so that an image was formed. The diameter of the semiconductor laser 
beam stop was 20 .mu.m.times.40 .mu.m, the image exposing energy was 30 
.mu.J/cm.sup.2 at the surface of the photosensitive member, and the 
exposing speed was 1.67.times.10.sup.-7 sec/dot. 
The transmitted optical density of the image exposed portion and the 
non-image-exposed portion between the image exposed portions of the 
obtained image were measured so that the resolution of the image was 
evaluated. The transmitted optical density to evaluate the resolution was 
measured by using a microspectroscope UMSP manufactured by Karltzwise with 
light, the wavelength of which was 550 nm.+-.5 nm. The results of the 
evaluation of the resolution were shown in Table 2. 
EXAMPLE 2 
The heat developing photosensitive member according to the present 
invention was manufactured under the same conditions as those of Example 1 
except use of the foregoing sensitizing dye (II-2) in place of the 
sensitizing dye (I-7) used in Example 1. 
The sensitivity and the fog density of the heat developing photosensitive 
member were measured similarly to Example 1. The results of the 
measurements were shown in Table 1. The resolution of the heat developing 
photosensitive member was measured similarly to Example 1. The results of 
the measurement was shown in Table 2. 
EXAMPLE 3 
The heat developing photosensitive member according to the present 
invention was manufactured under the same conditions as those of Example 1 
except use of the foregoing sensitizing dye (III-3) in place of the 
sensitizing dye (I-7) used in Example 1. 
The sensitivity and the fog density of the heat developing photosensitive 
member were measured similarly to Example 1. The results of the 
measurements were shown in Table 1. The resolution of the heat developing 
Comparative Examples 1, 2 and 3 
Three types heat developing photosensitive members were manufactured under 
the same conditions as those of Example 1 except use of the following 
sensitizing pigment (R-1), (R-2) or (R-3) in place of the sensitizing 
pigment (I-7) used in Example 1. 
The sensitivity and the fog density of the heat developing photosensitive 
member were measured similarly to Example 1. The results of the 
measurements were shown in Table 1. 
##STR11## 
EXAMPLE 4 
A photosensitive composition having the following composition was prepared 
with safety light applied to the same. 
______________________________________ 
Polyvinylbutyral 3.0 g 
Silver Behenate 2.5 g 
Behenic Acid 1.5 g 
Silver Bromide 0.6 g 
Homophthalic acid 0.6 g 
Phthalazinone 0.5 g 
2,2'-methylene bis (4,6-di-t-butylphenol) 
2.6 g 
Xylene 30 ml 
n-butanol 40 ml 
______________________________________ 
The silver bromide is in the form of cubic crystal, the plane index of 
which was {100}and an average length of one side of which was 0.06 .mu.m. 
1.5 mg of the sensitizing dye (I-7) and 5 mg of cyanine dye (IV-4) were 
dissolved in 10 ml of N,N-dimethyl formamide (DMF). Solution thus obtained 
was added to the foregoing photosensitive composition. 
The photosensitive composition, to which the sensitizing dye (I-7) and the 
cyanine dye (IV-4) were added, was applied to the upper surface of a 
polyethylene terephthalate (PET) film to have a dry thickness of 10 .mu.m 
so that a photosensitive layer was formed. Furthermore, a protection layer 
was formed by applying a polyvinyl alcohol layer having a dry thickness of 
2 .mu.m so that the heat developing photosensitive member according to the 
present invention was obtained. 
The thus-obtained heat developing photosensitive member was subjected to 
evaluations of the sensitivity and the fog density immediately similarly 
to Example 1. 
The results of the measurements were shown in Table 1. Further, the 
resolution of the foregoing heat developing photosensitive member was 
evaluated similarly to Example 1, the results being shown in Table 2. 
EXAMPLE 5 
The heat developing photosensitive member according to the present 
invention was manufactured under the same conditions as those of Example 4 
except use of the foregoing sensitizing dye (II-2) in place of the 
sensitizing dye (I-7) used in Example 4. 
The sensitivity and the fog density of the heat developing photosensitive 
member were measured similarly to Example 1. The results of the 
measurements were shown in Table 1. The resolution of the heat developing 
photosensitive member was measured similarly to Example 1. The results of 
the measurement was shown in Table 2. 
EXAMPLE 6 
The heat developing photosensitive member according to the present 
invention was manufactured under the same conditions as those of Example 4 
except use of the foregoing sensitizing dye (III-3) in place of the 
sensitizing dye (I-7) used in Example 4. 
The sensitivity and the fog density of the heat developing photosensitive 
member were measured similarly to Example 1. The results of the 
measurements were shown in Table 1. The resolution of the heat developing 
photosensitive member was measured similarly to Example 1. The results of 
the measurement was shown in Table 2. 
TABLE 1 
______________________________________ 
Initial Stage Post Durability Test 
Sensitivity 
Fog Sensitivity 
Fog 
(.mu.J/cm.sup.2) 
Density (.mu.J/cm.sup.2) 
Density 
______________________________________ 
Example 1 4.5 0.14 4.4 0.15 
Example 2 5.6 0.10 6.3 0.10 
Example 3 5.2 0.15 6.0 0.16 
Example 4 3.9 0.14 3.9 0.14 
Example 5 5.0 0.10 5.2 0.10 
Example 6 4.8 0.15 5.0 0.15 
Comparative 
980.0 0.14 1264.0 0.21 
Example 1 
Comparative 
17.5 0.80 24.3 0.91 
Example 2 
Comparative 
22.5 0.12 31.2 0.20 
Example 3 
______________________________________ 
TABLE 2 
______________________________________ 
Resolution 
300 dpi 
600 dpi 900 dpi 
______________________________________ 
Exam- Density of Exposed Portion 
2.85 2.57 2.16 
ple 1 Density of Un-Exposed portion 
0.46 0.51 0.63 
Exam- Density of Exposed Portion 
2.65 2.47 1.98 
ple 2 Density of Un-Exposed portion 
0.30 0.32 0.39 
Exam- Density of Exposed Portion 
2.67 2.54 2.09 
ple 3 Density of Un-Exposed portion 
0.50 0.57 0.68 
Exam- Density of Exposed Portion 
2.90 2.74 2.43 
ple 4 Density of Un-Exposed portion 
0.21 0.27 0.39 
Exam- Density of Exposed Portion 
2.75 2.59 2.36 
ple 5 Density of Un-Exposed portion 
0.18 0.25 0.34 
Exam- Density of Exposed Portion 
2.80 2.64 2.39 
ple 6 Density of Un-Exposed portion 
0.34 0.38 0.42 
______________________________________ 
As can be understood from Table 1, the heat developing photosensitive 
member according to the present invention exhibits superior sensitivity 
and low fog density to those of the conventional heat developing 
photosensitive member. 
Furthermore, as can be understood from Table 2, use of the cyanine dye 
improves the resolution. 
Although the invention has been described in its preferred form with a 
certain degree of particularly, it is understood that the present 
disclosure of the preferred form can be changed in the details of 
construction and the combination and arrangement of parts may be resorted 
to without departing from the spirit and the scope of the invention as 
hereinafter claimed.