Iron type golf club head

1. An iron type golf club head comprising a hitting face, a hosel, and a sole, wherein

the hitting face includes a face center and a sweet spot,

the hitting face has a face height that is denoted by Hf (mm), the face height Hf being measured along the hitting face at a toe-heel direction position of the face center,

the sweet spot has a vertical height that is denoted by Hs (mm),

the face center has a vertical height that is denoted by Hc (mm),

the vertical height Hc is greater than or equal to 20 mm and less than or equal to 26 mm,

the face height Hf is greater than or equal to 40 mm and less than or equal to 52 mm, and

the head satisfies expression 1 shown below:

Hs< 0.06* Hf+ 16  (expression 1),

wherein the vertical height Hs of the sweet spot is greater than or equal to 16 mm and less than or equal to 20 mm.

2. The iron type golf club head according to claim 1 further comprising a head body and a face member attached to the head body, wherein

the face member has a specific gravity that is smaller than a specific gravity of the head body.

3. The iron type golf club head according to claim 1 , wherein

an expected COR is greater than or equal to 0.740, the expected COR being a sum total of values obtained by multiplying hitting probabilities in respective positions or zones on the hitting face by respectively corresponding COR values in the respective positions or zones.

4. The iron type golf club head according to claim 3 , wherein

an effective hitting area is set on a part of the hitting face, and

the expected COR is a sum total of values obtained by multiplying hitting probabilities in respective positions or zones of the effective hitting area by respectively corresponding COR values in the respective positions or zones of the effective hitting area.

5. The iron type golf club head according to claim 4 , wherein the effective hitting area has a centroid that is located on a toe-heel direction position coinciding with the toe-heel direction position of the face center.

6. The iron type golf club head according to claim 4 , wherein the effective hitting area has a centroid that is positioned on a sole side relative to the face center.

7. The iron type golf club head according to claim 1 , wherein

a CORmax is less than or equal to 0.840, the CORmax being a maximum COR value.

8. The iron type golf club head according to claim 1 , wherein

the sweet spot is positioned on a sole side relative to the face center, and

a distance in a top-sole direction between the sweet spot and the face center is greater than or equal to 3.5 mm and less than or equal to 7 mm.

9. The iron type golf club head according to claim 1 , wherein

the hitting face includes a longest face line,

a distance between a heel-side end of the longest face line and a toe-side end of the head is defined as a face length, and

the face length is greater than or equal to 68 mm and less than or equal to 80 mm.

10. An iron type golf club head comprising a hitting face, a hosel, and a sole, wherein

the hitting face includes a face center and a sweet spot,

the hitting face has a face height that is denoted by Hf (mm), the face height Hf being measured along the hitting face at a toe-heel direction position of the face center,

the sweet spot has a vertical height that is denoted by Hs (mm),

the face center has a vertical height that is denoted by Hc (mm),

the vertical height Hc is greater than or equal to 20 mm and less than or equal to 26 mm,

the face height Hf is greater than or equal to 40 mm and less than or equal to 52 mm, and

the head satisfies expression 1 shown below:

Hs< 0.06* Hf+ 16  (expression 1),

wherein

the hosel includes a hosel hole and a hosel end surface, and

in a reference state where the head is placed on a horizontal plane, a distance from the hosel end surface to an intersection point between a center line of the hosel hole and the horizontal plane is defined as a neck length L 2 , and the neck length L 2 is greater than or equal to 40 mm and less than or equal to 60 mm,

wherein a ratio L 2 /Hf of the neck length L 2 to the face height Hf is greater than or equal to 1.1 and less than or equal to 1.3,

wherein

the sole has a sole width W 1 that is measured at the toe-heel direction position of the face center, and

a ratio W 1 /Hf of the sole width W 1 to the face height Hf is greater than or equal to 0.60 and less than or equal to 0.78.

11. The iron type golf club head according to claim 10 , wherein a ratio W 1 /L 2 of the sole width W 1 to the neck length L 2 is greater than or equal to 0.50 and less than or equal to 0.65.

12. An iron type golf club head comprising a hitting face, a hosel, and a sole, wherein

the hitting face includes a face center and a sweet spot,

the hitting face has a face height that is denoted by Hf (mm), the face height Hf being measured along the hitting face at a toe-heel direction position of the face center,

the sweet spot has a vertical height that is denoted by Hs (mm),

the face center has a vertical height that is denoted by Hc (mm),

the vertical height Hc is greater than or equal to 20 mm and less than or equal to 26 mm,

the face height Hf is greater than or equal to 40 mm and less than or equal to 52 mm, and

the head satisfies expression 1 shown below:

Hs< 0.06* Hf+ 16  (expression 1),

wherein

the sole has a sole width W 1 that is measured at the toe-heel direction position of the face center, and

a ratio W 1 /Hf of the sole width W 1 to the face height Hf is greater than or equal to 0.60 and less than or equal to 0.78.

13. An iron type golf club head comprising a hitting face, a hosel, and a sole, wherein

the hitting face includes a face center and a sweet spot,

the hitting face has a face height that is denoted by Hf (mm), the face height Hf being measured along the hitting face at a toe-heel direction position of the face center,

the sweet spot has a vertical height that is denoted by Hs (mm),

the face center has a vertical height that is denoted by Hc (mm),

the vertical height Hc is greater than or equal to 20 mm and less than or equal to 26 mm,

the face height Hf is greater than or equal to 40 mm and less than or equal to 52 mm, and

the head satisfies expression 1 shown below:

Hs< 0.06* Hf+ 16  (expression 1),

wherein

the hosel includes a hosel hole and a hosel end surface,

in a reference state where the head is placed on a horizontal plane, a distance from the hosel end surface to an intersection point between a center line of the hosel hole and the horizontal plane is defined as a neck length L 2 ,

the sole has a sole width W 1 that is measured at the toe-heel direction position of the face center, and

a ratio W 1 /L 2 of the sole width W 1 to the neck length L 2 is greater than or equal to 0.50 and less than or equal to 0.65.