A retinal implant can include an array of photoreceptors adapted for positioning in the eye. The plural portions have a first portion and a second portion and each of the first portion and the second portion has a first region and a second region. Said assembly device is in particular suitable for tools such as actuators or pliers, i. Since PNum x copies have already been output at that time, N copies as the remainder of division of UNum by PNum suffice to be printed by the final job. The device can be used in a method of attachment onto an apertured surface, in particular the inner surface of an automatic laundry washing machine drum, and is particularly suitable for dispensing rinse additives into the rinse cycle of an automatic washing machine. The modulation controller selects a unit period, where the intensity error which occurs with the output fluctuation point being inserted is predicted not to be visually recognized with human’s eyesight characteristics, from the unit periods, and controls arrangement of the unit periods so that the output fluctuation point is inserted into the selected unit period.