WE CLAIM:
[Claim 1]
A negative type photosensitive resin composition comprising, as an alkali-soluble resin (A),
at least a weakly acidic group-containing resin (A1) and an unsaturated group-containing
resin (A2),
the weakly acidic group-containing resin (A1) containing an acidic group having an acid
dissociation constant in the range of 13.0 to 23.0 in dimethyl sulfoxide, and
the unsaturated group-containing resin (A2) having an ethylenically unsaturated double
bond group.
[Claim 2]
A negative type photosensitive resin composition as set forth in claim 1, wherein the weakly
acidic group-containing resin (A1) having one or more acidic groups selected from the group
consisting of phenolic hydroxyl group, silanol group, hydroxyimide group, and hydroxyamide
group.
[Claim 3]
A negative type photosensitive resin composition as set forth in either claim 1 or 2 further
comprising a radical-polymerizable compound (B) and a photosensitive agent (C).
[Claim 4]
A negative type photosensitive resin composition as set forth in any one of claims 1 to 3,
wherein the weakly acidic group-containing resin (A1) having no ethylenically unsaturated
double bond group, and
the weakly acidic group-containing resin (A1) accounting for 30 to 99 mass% of the
alkali-soluble resin (A).
[Claim 5]
A negative type photosensitive resin composition as set forth in claim 4, wherein the weakly
acidic group-containing resin (A1) accounts for 70 to 97 mass% of the alkali-soluble resin
(A).
[Claim 6]
A negative type photosensitive resin composition as set forth in any one of claims 1 to 5,
wherein the weakly acidic group-containing resin (A1) has an acid equivalent in the range of
200 to 1,200 g/mol.
[Claim 7]
A negative type photosensitive resin composition as set forth in any one of claims 1 to 6,
wherein the unsaturated group-containing resin (A2) has a double bond equivalent in the
range of 250 to 5,000 g/mol.
[Claim 8]
A negative type photosensitive resin composition as set forth in any one of claims 1 to 7

further comprising a coloring agent (D).
[Claim 9]
A negative type photosensitive resin composition as set forth in any one of claims 1 to 8,
wherein the weakly acidic group-containing resin (A1) includes one or more selected from
the group consisting of polyimide (A1a-1), polyimide precursor (A1a-2), carboxylic
acid-modified polysiloxane (A1a-3), carboxylic acid-modified novolac resin (A1a-4),
carboxylic acid-modified polyhydroxystyrene (A1a-5), polybenzoxazole (A1b-1),
polybenzoxazole precursor (A1b-2), polysiloxane (A1b-3), novolac resin (A1b-4), and
polyhydroxystyrene (A1b-5).
[Claim 10]
A negative type photosensitive resin composition as set forth in any one of claims 1 to 9,
wherein the unsaturated group-containing resin (A2) includes one or more selected from the
group consisting of unsaturated group-containing polyimide (A2a-1), unsaturated
group-containing polyimide precursor (A2a-2), carboxylic acid-modified unsaturated
group-containing polysiloxane (A2a-3), unsaturated group-containing polybenzoxazole
(A2b-1), unsaturated group-containing polybenzoxazole precursor (A2b-2), unsaturated
group-containing polysiloxane (A2b-3), polycyclic side chain-containing aromatic resin
(A2c-1), acrylic resin (A2c-2), and carboxylic acid-modified epoxy resin (A2c-3).
[Claim 11]
A cured film formed by curing a negative type photosensitive resin composition as set forth in
any one of claims 1 to 10.
[Claim 12]
A cured film as set forth in claim 11, wherein the optical density per micrometer of film
thickness is in the range of 0.3 to 5.0.
[Claim 13]
A display device comprising a cured film as set forth in either claim 11 or 12.
[Claim 14]
A display device as set forth in claim 13, wherein the cured film is a step-shaped cured
pattern.
[Claim 15]
A display device as set forth in claim 14, wherein the cross section of the step-shaped cured
pattern has an oblique side with a taper angle in the range of 1 ° to 60°.
[Claim 16]
A display device as set forth in either claim 14 or 15, wherein the film thickness difference
(ATFTHT) um between (TFT) and (THT) wherein (TFT) um denotes the film thickness of the
thick parts and (THT) um denotes the film thickness of the thin parts in the stepped shape of
the cured pattern is in the range of 0.5 to 10.0 urn.
[Claim 17]

A display device as set forth in claim 16, wherein (TFT) and (THT) meet the relations
represented by general formulae (a) to (v):
2.0<(TFT)<10 (a)
0.10 <(THT)^ 7.5 (p)
0.10 x (TFT) < (THT) ^ 0.75 x(TFT) (Y)
[Claim 18]
A display device as set forth in claim 16, wherein (TFT) and (THT) further meet the relations
represented by general formulae (5) to (Q3.0 < (TFT) < 9.0 (5)
0.20 < (THT) ^ 7.0 (£)
0.20 x (TFT) ^ (THT) * 0.70 x (TFT) (Q
[Claim 19]
A display device as set forth in any one of claims 15 to 18 comprising a curved display part
having a curvature radius in the range of 0.1 to 10 mm.
[Claim 20]
A display device as set forth in any one of claims 13 to 19 in the form of an organic EL
display device or a liquid crystal display device.
[Claim 21]
A production method for display device comprising:
(1) a step for forming a coating film of a negative type photosensitive resin composition as set forth in any one of claims 1 to 10 on a substrate,
(2) a step for applying active actinic ray to the resin composition through a photomask,
(3) a step for developing it with an alkaline solution to form a step-shaped pattern of the resin composition, and,
(4) a step for heating the pattern to produce a step-shaped cured pattern of the resin composition,
the photomask being one that has a pattern containing transparent portions and light blocking portions and that also has translucent portions lower in transmittance than the transparent portions, higher in transmittance than the light blocking portions, and located between the transparent portions and the light blocking portions.