Abstract: An automatic recording instrument has an array of store-pen-holders. To each store-pen-holder, a recording pen is assigned and is held when the pen is not in use. A moving pen-holder with a recording-pen, is computer-controlled to draw a desired trace on a recording-paper by the pen. In order to transfer a recording-pen from a store-pen-holder to the moving pen-holder, the latter comes to the position of the store-pen-holder from a first direction in which the moving pen-holder has an opening to admit the path of the recording-pen, holds the recording-pen by a magnetic clutch, and then recedes in a second direction in which the store-pen-holder has an opening to admit the path of the recording-pen. After the assigned pen is taken by the moving pen-holder, the store-pen-holder remains empty. In order to return the pen to this empty store-pen-holder, the moving pen-holder comes to the store-pen-holder from the second direction, releases the pen to the store-pen-holder, and recedes in the first direction.

Abstract: In a multi-channel recording instrument, the reference signal of each channel is floating from the ground level. Therefore, one each isolated power supply means must be provided for each channel. However, when the error signal for each channel is transmitted through a photo-coupler, the circuit after the photo-coupler can be isolated from the biasing voltage of the reference signal, and a common power supply can be used for all the stages after the photo-couplers, including servo-motor drivers, of all the channels. This reduces the size and cost of the power supplies as a whole. The non-linear character of the photo-coupler does not cause a positioning error, since the photo-coupler is in the servo-loop having a sufficiently large gain.

Abstract: A thermal recording stylus has a recording head made of Type IIa diamond. The type IIa diamond has a very good heat conductivity and an excellent abrasion-resistant property. Therefore, the thermal recording stylus with the recording head made of Type IIa diamond has an improved thermal response character, a higher resolution in drawing a line, and a longer life.