JPH0473154B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention forms an image of a document as an electrostatic latent image on an image carrier, develops the electrostatic latent image with toner, and transfers it to a transfer paper. Regarding an electrostatic recording device that fixes images, more specifically, an image recording device that has improved paper jam detection means that detects when a transfer paper to which a toner image on an image bearing member has been transferred does not separate from the photoreceptor. Regarding equipment.

(Prior Art) Among the electrostatic recording devices described above, an electrophotographic copying device is schematically configured as shown in FIG. When the original 2 is set on the surface of the platen glass 1 and the copy start button is operated, the exposure light source 3 scans the original 2 for exposure, and the light image of the original 2 passes through the mirrors 4 and 5. and guided to the surface of the photosensitive drum 6 as an image carrier. This photosensitive drum 6
A photoconductive layer made of selenium or the like is provided on the outer peripheral surface of a grounded metal tube, and rotates in the direction of arrow a in conjunction with the exposure scanning.

Before the arrival of the optical image on the photosensitive drum 6, the photoconductive layer is, for example, uniformly charged by a charging electrode 7 to which a DC high voltage is applied, and the photoconductive layer in this state is used as the optical image. When exposed to light, the conductivity of the part that received the light increases and the electrical charge in that part escapes to the metal tube, leaving a positive charge in the dark part depending on the degree of brightness. As a result, an electrostatic latent image corresponding to the image of the original is formed on the surface of the photoconductive layer.

When the portion on which this electrostatic latent image is formed reaches the developing sleeve 8a of the developing device 8, the negatively charged toner is attracted to the remaining positively charged portion of the photosensitive drum 6 by electrostatic force. . As a result,
A toner image corresponding to the electrostatic latent image is formed on the surface of the photosensitive drum 6.

The transfer paper 9 is sent out from the paper feed cassette 10 by the conveyor belt 11 at a timing such that the leading edge of the transfer paper 9 and the leading edge of the toner image coincide with each other. is applied to the transfer pole 12, the photosensitive drum 6
The developer image on the surface of is transferred.

Thereafter, the transfer paper 9 is separated from the photosensitive drum 6 by the separation electrode 13 and the separation claw 14 to which AC high voltage is applied, and is sent to the fixing device 16 by the conveyor belt 15, where the toner image is fixed on the receiving tray 17. be discharged.

Reference numeral 18 denotes a light-reflection type paper jam sensor that detects transfer paper that arrives unseparated from the surface of the photosensitive drum 6 and remains wrapped around it, 19 a removing electrode that removes the electrical charge on the photosensitive drum 6, and 20 a removal electrode for removing the electrical charge on the photosensitive drum 6. This is a cleaning device that removes toner remaining on the surface.

(Problem to be Solved by the Invention) In such an electrophotographic copying apparatus, for example, when red toner is used, the paper jam sensor 18 detects the spectral wavelength of the red toner. If the photosensitive drum 6 has a spectral sensitivity, when the amount of reflected light from the red toner remaining on the surface of the photosensitive drum 6 is large, a detection output similar to that when the transfer paper is wrapped around the surface of the photosensitive drum 6 is generated. In such cases, there is a problem in that accurate detection of paper jams cannot be performed.

The present invention has been made in view of the above, and an object of the present invention is to provide an image recording system that enables accurate detection of paper jams when one or more color toners are used as toners. The purpose is to provide equipment.

(Means for Solving the Problems) To this end, the present invention provides a developing device that develops an electrostatic latent image formed on an image carrier using one or more color toners to form a color toner image. , a transfer means for transferring the color toner image onto a transfer paper, and a separation means for separating the transfer paper from the image carrier, and optically removes the transfer paper wrapped around the image carrier due to poor separation of the transfer paper. In the image recording apparatus, the detection means has a high spectral sensitivity in a wavelength range where the reflectance is low in the spectral reflectance distribution of the single color or multiple color toners used,
It has a light receiving means with low spectral sensitivity in a wavelength range of high reflectance and a comparison circuit that compares the signal from the light receiving means with a predetermined reference voltage, and outputs a paper separation failure signal when the transfer paper fails to separate. It was configured as follows.

(Example) Examples of the present invention will be described below. First, FIG. 2 shows the characteristics (distribution) of spectral reflectance of red, sepia, and blue toners, which are typical color toners. According to this characteristic, Red is
The reflectance suddenly increases for light with wavelengths exceeding 660 nm, and the reflectance is less than 20% for wavelengths below that. In addition, Sepia has a rapidly increasing reflectance for light with wavelengths exceeding 710 nm.
Below that, it is less than 20%. Furthermore, blue is 420
The reflectance is high for light with wavelengths between ~500 nm and over 720 nm, and is less than 20% for other wavelengths. On the other hand, the reflectance of transfer paper is well over 20% for normal visible light.

Therefore, the paper jam sensor 18 detects the developer remaining on the surface of the photosensitive drum 6 and the photosensitive drum 6.
In order to identify the transfer paper wrapped around the paper jam sensor 18, it is necessary to configure the paper jam sensor 18 so that it is sensitive to wavelengths at which the reflectance of each color toner is low.

Based on the above characteristics, if the sensor is configured to be sensitive to light with a wavelength between 500 nm and 660 nm, it is possible to distinguish between blue, red, and sepia color toners and transfer paper. , also 420nm
Even if the sensor is configured to be sensitive to light of the following wavelengths, it is possible to similarly distinguish between blue, red, and sepia color toners and transfer paper.

From the above, by making the sensor sensitive to light with a wavelength between 500nm and 660nm, or with a sensitivity to light with a wavelength of 420nm or less, it is possible to use typical blue, red, and sepia color toners. On the other hand, paper jams can be detected without error.

FIG. 3 shows a cross section of the paper jam sensor 18, and shows optical paths 18b and 18c formed in the main body 18a.
Illumination LEDs (light-emitting diodes,
Same hereafter) 18d, phototransistor for light reception 18
e is provided, and the light emitted from the irradiation LED 18d passes through the optical path 18b, is reflected on the surface of the photosensitive drum 6, and is configured to enter the light receiving phototransistor 18e via the optical path 18c.
The LED 18d is one that emits visible light, and the phototransistor 18e is one that is sensitive to light with wavelengths between 500 nm and 660 nm or 420 nm or less, as described above. There is.

FIG. 4 shows the configuration of the detection means, and shows a detection circuit for processing the detection signal from the sensor 18, which is a reflective optical sensor, to obtain a paper jam signal. The LED 18d of the paper jam sensor 18 is connected in series with the resistor R1 in the forward direction between the power supply Vcc and the ground.
A phototransistor 18e that receives the reflected light of the projection light from the LED 18d is connected between the power supply Vcc and the inverting input terminal of the operational amplifier 21. The non-inverting input terminal of this operational amplifier 21 has a power supply voltage
A voltage obtained by dividing Vcc by resistors R2 and R3 is applied, and its output terminal is connected to an inverting input terminal by a resistor R4 and also to an inverting input terminal of the comparator 22. The power supply voltage Vcc is connected to the non-inverting input terminal of this comparator 22 through resistors R5 and R
The voltage divided by 6 is input as the comparison reference voltage.

In this detection circuit, the larger the amount of reflected light that enters the phototransistor 18e (however, it is limited to light with a wavelength within the above range to which the phototransistor 18e is sensitive), the more the phototransistor 18e
has a large emitter current, and this current flows through operational amplifier 2.
1, it is converted to voltage and amplified. The output from the operational amplifier 21 is the phototransistor 18.
As the amount of light reflected to e increases, the amount of light decreases and is input to the comparator 22 at the next stage. In this comparator 22, when the output from the operational amplifier 21 to the inverting input terminal becomes lower than the reference voltage applied to the non-inverting input terminal, the output voltage becomes high level, indicating that a paper jam has been detected. represent.

(Effects of the Invention) As described above, according to the present invention, even if the image recording apparatus uses one or more color toners,
A feature of this method is that it is possible to accurately detect a transfer sheet that is poorly separated without erroneously detecting the toner remaining on the image carrier.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of an electronic copying device, Figure 2 is a characteristic diagram of spectral reflectance of various color toners, and Figure 3 is a diagram of the spectral reflectance characteristics of various color toners.
The figure is a sectional view of the paper jam sensor, and FIG. 4 is a circuit diagram of the detection circuit. DESCRIPTION OF SYMBOLS 1...Platen glass, 2...Document, 3...Light source for exposure, 4, 5...Mirror, 6...Photosensitive drum, 7...Charging electrode, 8...Developing device, 9...Transfer paper, 10 ...Paper feed cassette, 11...Transport belt, 12...Transfer pole, 13...Separation pole, 14...
Separation claw, 15... Conveyor belt, 16... Fixing device, 17... Receiver, 18... Paper jam sensor, 1
9... Eliminating electrode, 20... Cleaning device, 21
...Operation amplifier, 22...Comparator.

Claims (1)

[Scope of Claims] 1. A developing device that forms a color toner image by developing an electrostatic latent image formed on an image carrier using one color toner or a plurality of color toners, and a developing device that forms a color toner image on a transfer paper. An image comprising a transfer means for transferring, a separation means for separating the transfer paper from the image carrier, and a detection means for optically detecting the transfer paper wrapped around the image carrier due to poor separation of the transfer paper. In the recording device, the detection means receives light having high spectral sensitivity in a wavelength range with low reflectance and low spectral sensitivity in a wavelength range with high reflectance in the spectral reflectance distribution of the single or multiple color toner used. and a comparison circuit for comparing the signal from the light receiving means with a predetermined reference voltage, and is configured to output a paper separation failure signal when the transfer paper fails to separate. .