US 6,473,106 B2 · LED head, image forming apparatus, and method of measuring amount of light from LED array

Abstract

An LED printer head capable of reducing influence of a sub emission band by use of a rod lens array and thus prevent light of the sub emission band from reaching a development level. The LED printer head consists of an LED array of LEDs to emit light according to an image signal, which are arrayed at the resolution pitch P of not less than 600 dpi, and a multi-lens array for forming an emission image of the LED array on a photosensitive body. Each of the LEDs of the LED array has a main emission band of an emission spectrum and another sub emission band having a peak level of not less than 0.01 as a photosensitive intensity ratio R to the main emission spectrum, and a difference D between best total conjugate lengths at peak wavelengths of the main and sub emission bands by the multi-lens array is at least 0.15. Optical adjustment of the LED array and the multi-lens array is effected so that light of the main emission band is focused in a predetermined imaging relation on the predetermined photosensitive body.

Claims31

Dependent claims

An LED head comprising an LED array of LEDs which emit light according to an image signal and which are arrayed at a resolution pitch P of not less than 600 dpi, and a multi-lens array for forming an emission image of said LED array on an information medium,

wherein each of said LEDs of the LED array has a main emission band being an emission spectrum for formation of a main image and a sub emission band apart from a peak wavelength of the emission spectrum of the main emission band, and
wherein a difference D between best total conjugate lengths at peak wavelengths of the emission spectrum of the main emission band and an emission spectrum of the sub emission band by said multi-lens array is at least 0.15 mm, and optical adjustment of said LED array and said multi-lens array is implemented so that light of the main emission band is focused in a predetermined imaging relation on a predetermined information medium.

A method of measuring an amount of light from an LED array, wherein there are provided an LED array of LEDs for an LED head and two sensor portions for receiving an amount of light emitted from an activated LED and generating an electric output corresponding to the amount of light received,

wherein the LED array of a measured object has a main emission band being an emission spectrum for formation of an image and a sub emission band being another emission spectrum apart from a peak wavelength of the emission spectrum of the main emission band,
wherein spectral sensitivity of the sensor portions has approximately flat characteristics for the main emission band and the sub emission band,
wherein an optical element for reflecting or transmitting a light amount of the main emission band and for transmitting or reflecting a light amount of the sub emission band is placed between the LED array and the two sensor portions,
wherein the light amount of the main emission band is measured by one sensor portion out of the two sensor portions and the light amount of the sub emission band by the other sensor portion, a predetermined operation is carried out over measurement data of the light amount of the main emission band and measurement data of the light amount of the sub emission band to obtain single light-amount measurement data, and emission characteristics of the LED array are measured.

1 more element

A method of measuring an amount of light from an LED array, wherein there are provided an LED array of LEDs for an LED head and a sensor portion for receiving an amount of light emitted from an activated LED and generating an electric output corresponding to the amount of light received,

wherein the LED array of a measured object has a main emission band being an emission spectrum for formation of an image and a sub emission band being another emission spectrum apart from a peak wavelength of the emission spectrum of the main emission band,
wherein spectral sensitivity of the sensor portion has approximately flat characteristics for the main emission band and the sub emission band,
wherein an optical element for cutting either a light amount of the sub emission band or a light amount of the main emission band is placed in a retractable state between the LED array and the sensor portion, a predetermined operation is carried out over two output signal values obtained from two states of presence and absence of the optical element from the sensor portion, and emission characteristics of the LED array are measured.

Dependencies are inferred from the claim text.

LED head, image forming apparatus, and method of measuring amount of light from LED array

Life of this patent

LED head, image forming apparatus, and method of measuring amount of light from LED array

Life of this patent

Abstract

Claims31