Dot matrix printers and print heads therefor

A print head for use in a multihead printing array comprising:

• a solenoid case including a sidewall and a pair of opposed bases axially aligned on and connected with said sidewall, one of said bases having an aperture formed therein, said case being made of a magentically permeable material,
• a core of magentically permeable material defining a solenoid axis and extending within said case from the non-apertured base to a point adjacent the apertured base, said core defining a pole surface exposed to the exterior of the case by way of said aperture,
• a solenoid coil disposed in said case about said core,
• a beam, having a mounting end and a print pin support end,
• means rigidly mounting said mounting end of said beam relative to said case to overlie said aperture,
• an armature mounted to said beam, extending into said aperture and defining a pole surface positioned to form a working magnetic gap with said pole surface of said core, and
• a straight print pin rigidly attached to the print pin support end of said beam and extending substantially parallel to the axis of said solenoid, whereby movement of said beam and attached armature toward said solenoid moves said print pin substantially prallel to said axis for printing motion thereof,
• a damper disposed to damp recoil energy of said beam, armature and print pin,
• said beam having a resilient portion disposed between said rigid mounting and said armature and being rigid from said armature to said print pin, and
• said pole surfaces being disposed at an angle to each other when said beam is at rest without any preload applied to the beam and being parallel to each other when the magnetic gap is closed,
• wherein said damper is a resilient damper plug provided with means for adjusting the position of the damper relative to the beam and with means disposed between said damper plug and said means for adjusting the same which permits the damper plug to rotate whereby said plug moves during operation to progressively change the location of impact thereon of said print pin beam assembly on recoil.

A print head for use in a multihead printing array comprising:

• a solenoid case including a sidewall and a pair of opposed bases axially aligned on and connected with said sidewall, one of said bases having an aperture formed therein, said case being made of a magnetically permeable material,
• a core of magnetically permeable material defining a solenoid axis and extending within said case from the non-apertured base to a point adjacent the apertured base, said core defining a pole surface exposed to the exterior of the case by way of said aperture,
• a solenoid coil disposed in said case about said core,
• a beam, having a mounting end and a print pin support end,
• means rigidly mounting said mouting end of said beam relative to said case to overlie said aperture,
• an armature mounted to said beam, extending into said aperture and defining a pole surface positioned to form a working magnetic gap with said pole surface of said core, and
• a straight print pin rigidly attached to the print pin support end of said beam and extending substantially parallel to the axis of said solenoid, whereby movement of said beam and attached armature toward said solenoid moves said print pin substantially parallel to said axis for printing motion thereof,
• a damper disposed to damp recoil energy of said beam, armature and print pin,
• said beam having a resilient portion disposed between said rigid mounting and said armature and being rigid from said armature to said print pin, and
• said pole surfaces being disposed at an angle to each other when said beam is at rest without any preload applied to the beam and being parallel to each other when the magnetic gap is closed,
• wherein said damper is a resilient damper plug provided with means for adjusting the position of the damper relative to the beam and with said damper incorporating an inertial element having an mass equivalent to that of the effective moving mass of the beam, armature and print pin.