JPS59143169A - Picture forming device - Google Patents

Abstract

PURPOSE:To stabilize the formation of pictures with a proper level of density by setting the density of information at a proper level after detecting the infrared light out of the image information. CONSTITUTION:The reflected light of an original 3 illuminated by a halogen lamp 1 is totally reflected by a mirror 4. The visible light is reflected by a spectral mirror 5; while the infrared light is transmitted through the mirror 5. This transmitted infrared light is detected by a photodiode 8, and the picture density of the original 3 is detected. This picture density is converted into electric signals and supplied to a lighting voltage controller 17. Then the lighting voltage of the lamp 1 is decided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus, and particularly to an image forming apparatus having means for optimizing the density of an image to be formed.

In general, electrophotographic devices such as copying machines are required to always produce easy-to-read, high-quality copied images regardless of the type of original, such as a blank original such as a report or a covered original such as a newspaper. For this reason, copying machines are equipped with functions such as dials and levers that are manually operated by the user to adjust the image density. However, it is quite difficult and troublesome for the user to obtain proper copy images for a wide variety of originals. Furthermore, in the case of originals with special images, there is an economical problem in that a proper copy image cannot be obtained unless the original is overcopied. For these reasons, in recent years there has been a demand for an image adjustment method that does not require the user to manually adjust the image density (that is, an image adjustment method that can always automatically and economically obtain a correct copy image regardless of the type of original). .

Conventionally, in order to overcome the above-mentioned problems, the original was irradiated with an appropriate amount of light in order to detect the image density of the original, and the reflected light was detected by a photodetector element installed in or around the optical path for image exposure. A method is adopted in which a predetermined conversion value is fed back to the image exposure amount or development bias according to this detection signal.

However, according to the above-mentioned conventional method, the image exposure amount of a copying machine is generally not composed of light in the infrared and ultraviolet wavelength ranges, but is determined by light in the visible wavelength range, and the photodetecting element mainly detects this image exposure. Since it detects light in the visible range, the image exposure amount is lost, and the light detection element blocks part of the exposed light, which may disturb the exposure distribution on the photoreceptor, and the effects of light that should not be detected, such as flare. The device has disadvantages such as being unable to be used for a long period of time because the device becomes dirty due to condensation, developer, etc.

In view of the above-mentioned problems, the present invention aims to solve these problems. The present invention solves the problems that have arisen in obtaining information density signals, and provides a painter forming device that can stabilize image formation and bring the formed image into an appropriate density state. It is.

A feature of the present invention is an image forming apparatus that has a member that separates infrared light from image information light and has image density optimization means that determines information density by detecting infrared light.

An embodiment of the present invention will now be described with reference to the drawings below. FIG. 7 is a schematic sectional view of an electrophotographic copying apparatus to which an embodiment of the present invention is applied, and FIG. 2 is a schematic circuit diagram of the embodiment of FIG.

In FIG. 7, the halogen lamp for document illumination illuminates the document 3 placed on the glass document table Ω, and the image of the document 3 is produced by the first mirror, which is a spectral light that transmits infrared light and reflects visible light. The photoreceptor 7 is exposed to light by an optical system consisting of a mirror mirror and a lens. On the back side of the spectroscopic mirror 5 through which the infrared light passes, a silicon photodiode g is placed surrounded by a dust box 7 and operated as an infrared detection element.

The photoreceptor 9 is charged in advance by the charging device 10, and then an electrostatic latent image is formed by exposing the original image to visible light reflected by the spectroscopic mirror S as described above, and this electrostatic latent image is transferred to the developing device. The transfer paper /3 is developed and visualized by //, and then fed from a paper feed section (not shown), and is brought into close contact with the photoreceptor 9, and the aforementioned developed image is transferred to the transfer paper by the transfer charging device /-2. /3 is transferred.

In Figure Ω, the infrared light transmitted through the spectroscopic mirror is detected and output by a photodiode, and the output signal is converted to voltage by an operational amplifier. /S is integrated. This output signal is amplified by the amplification circuit B and input to a device that controls the lighting voltage of the halogen lamp.

The operation of the above embodiment will be explained below with reference to the drawings. The original 3 is placed on the original platen a, and the halogen lamp is turned on at a constant voltage VO before exposing the original to be described later. The light reflected from the illuminated original 3 is totally reflected by the first mirror, visible light is reflected by the spectroscopic mirror 3, and infrared light is transmitted.

The transmitted infrared light is detected by photodiode g,
The image density of the original is detected. Since the photoconductor wa is reactive to visible light and does not sense infrared regions, there is no needless loss of image exposure (・0 Here, the spectral mirror ratio varies depending on the spectral sensitivity of the photoconductor 9, but 0, '71tm to sμm
It is desirable that light of a certain wavelength be transmitted.

Next, the output of the silicon photodiode is increased by 1
The detected current is input to the amplifier/amplifier and converted into a voltage, and the converted voltage is input to the operational amplifier/amplifier and integrated. In other words, the image density of original 3 is determined by the diode and the calculation increase d]
The signal is converted into an electrical signal by the converter/group 15. The converted output signal is amplified by the amplification circuit/B and inputted to the lighting voltage control device/7 to determine the appropriate lighting voltage VO1V of the halogen lamp. Here, V is a feedback amount to the lighting voltage of the lamp, which changes depending on the image density of the original.

As mentioned above, the halogen lamp / is lit at the lighting voltage VO + V to illuminate the document 3, and the document image is
The photoreceptor 9 is exposed to light by an optical system consisting of a mirror S and a lens B, and is transferred to the transfer paper 3 as described above.

According to the above embodiment, originals with different image densities, such as newspapers and blank originals, were copied, and appropriate copied images could be obtained in all cases. Although a silicon photodiode was used as the infrared detection element in this embodiment, it is also possible to use a silicon photocell, a PbS photoconductive cell, a Pb5e photoconductive cell, an InAS photoconductive cell, or an InSb photoconductive cell. Furthermore, since the infrared detection element is protected by a dustproof box, it is not contaminated by toner or the like, and the density of the document can be accurately measured for a long time.

In the embodiment described above, a mirror that transmits infrared light and reflects visible light is provided, and the density of the original is detected by detecting the infrared light transmitted through this mirror, and the image formed is corrected. As shown in FIG. 3, it is also possible to provide a spectral mirror 7' that reflects infrared light and transmits it through the visible (visible) IC, and to correct the image using the infrared light reflected from the spectral mirror 7. Note that image formation is performed based on the transmitted visible light.

In FIG. 3, the second reflecting mirror 7' reflects both infrared light and visible light, and the spectroscopic mirror 7' for infrared reflection, which reflects infrared light and transmits visible light, is connected to the lens. A silicon photodiode g' is provided between the photosensitive table 9 and the photosensitive table 9, and is further provided outside the image forming optical path for detecting the reflected infrared light.

The infrared light reflected by the infrared reflecting mirror 7' is detected by a diode g', and its signal is input to a circuit as shown in FIG. 2 to control the image density. Note that the second mirror s' is
It is a total reflection mirror similar to Mirag.

In the above-mentioned embodiments, the image density of the original is detected and the lighting voltage of the halogen lamp (one of the image forming conditions) is changed based on the signal. It is also possible to obtain an appropriate copy image by adjusting at least one image forming condition such as aperture (aperture, etc.) and charge amount correction.

As explained above, infrared light is separated from the reflected light from the original and optical information from the information carrier, the sensitivity of the original and optical information is detected based on this infrared light, and the sensitivity of the original and optical information is detected based on this detection signal. Since the density of the formed image is optimized, the image exposure amount for image formation that is in the optical path is not lost, and proper copying is always possible economically and easily for the user. This has the effect of allowing images to be obtained.At the same time, it has the effect of being able to remove the infrared absorption filter used to correct the spectral sensitivity of the photoreceptor in conventional copying machines.
Furthermore, it is particularly effective for copying machines that use black body radiation lamps such as halogen lamps and lamps that emit large amounts of radiant energy in the infrared region.

As described above, the present invention is capable of detecting information density without impairing the exposure amount for image formation, and can obtain an image with stable blood pressure density. (A) The invention provides an effective effect to an image forming apparatus to which the above technical concept can be applied, and includes the following.

[Brief explanation of the drawing]

FIG. 7 is a schematic sectional view of one embodiment of the present invention;
The figure is a schematic circuit diagram of the embodiment of FIG. FIG. 3 is a schematic cross-sectional view of another embodiment of the invention. /...Halogen lamp, 5.5' reflection mirror. 7. Dustproof box, 7. Infrared reflector. g, g'...Silicon photodiode, F...photoreceptor. // ・Developing device, /ri... Arithmetic amplification type for current-voltage conversion, /! ;...Arithmetic amplifier for integration. /Otsu...Width increasing circuit, /7...Lighting voltage control device.

Claims (1)

[Claims] a member provided in an optical path for transmitting image information and for separating infrared light from the image information light; a means for detecting the infrared light separated by the dispersing member; An image forming apparatus that has means for controlling image forming conditions and can adjust the density of an image to be formed to an appropriate IF.