Abstract: A paper feed tray unit for a printer comprises: a paper sensor for detecting a paper on a support; a guide position sensor formed of a reflection photosensor for detecting the position of slide guides; and a paper width detection sheet with marker lines having reflectances corresponding to paper sizes. A controller detects a paper on the support using the paper sensor. If no paper is present, the controller recognizes the position of the slide guides based on a signal from the guide position sensor detected from the paper width detection sheet, and controls a drive mechanism to move the slide guides to a position corresponding to a paper size input by a user before placing a paper on the support. This enables easy paper setting on the support, and prevents the slide guides from moving if a paper is present on the support, preventing the paper from being crushed.

Abstract: In an ink jet printer using an ink cartridge having an ink tank for storing ink therein and a recording head for ejecting the ink stored in the ink tank as ink drops and forming an image on a recording paper sheet, the detection accuracy of a displacement detection sensor for detecting a displacement of printing position is improved while reducing manufacturing costs of the displacement detection sensor. The displacement detection sensor is comprised of a light emitting device for emitting diffused light, a first lens for focusing the light emitted from the light emitting device on a recording paper sheet, a second lens for focusing the light reflected by the recording paper sheet and a light receiving device for receiving the light focused by the second lens.

Abstract: A paper feed tray unit for a printer comprises: a paper sensor for detecting a paper on a support; a guide position sensor formed of a reflection photosensor for detecting the position of slide guides; and a paper width detection sheet with marker lines having reflectances corresponding to paper sizes. A controller detects a paper on the support using the paper sensor. If no paper is present, the controller recognizes the position of the slide guides based on a signal from the guide position sensor detected from the paper width detection sheet, and controls a drive mechanism to move the slide guides to a position corresponding to a paper size input by a user before placing a paper on the support. This enables easy paper setting on the support, and prevents the slide guides from moving if a paper is present on the support, preventing the paper from being crushed.

Abstract: In an ink jet printer using an ink cartridge having an ink tank for storing ink therein and a recording head for ejecting the ink stored in the ink tank as ink drops and forming an image on a recording paper sheet, the detection accuracy of a displacement detection sensor for detecting a displacement of printing position is improved while reducing manufacturing costs of the displacement detection sensor. The displacement detection sensor is comprised of a light emitting device for emitting diffused light, a first lens for focusing the light emitted from the light emitting device on a recording paper sheet, a second lens for focusing the light reflected by the recording paper sheet and a light receiving device for receiving the light focused by the second lens.