JPS62146876A - Printer device - Google Patents

Abstract

PURPOSE:To certainly detect a joint part free from error by setting the optimum threshold value corresponding to the variable signals supplied from a detecting means by a threshold value setting means and comparing said signal with the threshold value and detecting the joint part of a conveyor belt. CONSTITUTION:When the level of the output signal of a joint detector 17 varies because of the scattering of donor or the influence of the outside light beam, and a joint part can not be detected after the lapse of time necessary for one turn of a conveyor belt 6, a threshold value determining means 32 determines the new threshold value corresponding to the signal supplied from the joint sensor 17 in substitution for the threshold value at present. The threshold value is compared with the detection signal in a control part 25, and the joint part of the conveyor belt 16 is detected free from error. The control part 25 controls the transport timing of the conveyor belt 16 so that a transcription material is not loaded onto the joint part on the basis of the detection of the joint part, and transports the transcription material.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a printer device used in an image forming device such as a color copying machine, and which conveys a transfer material to a transfer section by a conveyor belt. The present invention relates to a printer device that controls the transfer material so that it does not ride on the seam of a conveyor belt when the transfer material is conveyed.

(B) Conventional technology Conventionally, in a printer device that conveys a transfer material to a transfer section using a conveyor belt, when the transfer material rides on the seam of the conveyor belt when conveying the transfer material, the dielectric constant changes due to the seam. Since the density of the transferred image in this area changes and the image quality of the transfer material deteriorates, the light reflectance of the seam area is changed to prevent the transfer material from riding on the seam of the conveyor belt, and a light reflection type seam sensor is used. The conveyance timing of the conveyor belt was controlled by detecting the seam. When detecting the seam, a certain threshold value is set to be compared with the output signal from the light receiving element of the seam sensor, and the seam is detected based on the magnitude of the output signal corresponding to the reflectance with respect to the threshold value.

(c) Problems to be Solved by the Invention By the way, if the threshold value is fixed to a constant value, the conveyor belt or the seam sensor will be contaminated due to toner scattering, and light from the seam and other parts of the conveyor belt will be contaminated. The difference in the reflectance of the seam may become small, or the sensitivity of the seam sensor may decrease, making it impossible to accurately detect the seam. In particular, if the printer is installed near a window where direct sunlight shines in, the difference in the level of reflected light at the seam will be small.
This tendency is noticeable. For this reason, it may not be possible to control the transfer material so that it does not get on the joint of the conveyor belt.

(b) Means for solving the problem The present invention aims to solve the above-mentioned problems, and is based on an optical sensor to detect the difference in the light level from the surface of the conveyor belt, thereby setting a threshold value. The present invention is characterized in that a threshold value setting means for setting is provided, and a seam of the conveyor belt is detected by comparing the threshold value set by the threshold value setting means with a signal from the optical sensor.

(E) Effect Based on the above configuration, when the light level detected by the optical sensor changes, the threshold setting means sets an appropriate threshold according to the level of the signal from the optical sensor, and the threshold value and the detection means The signals are compared and the seams of the conveyor belt are detected without error.

(F) Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The printer device M of this embodiment is a four-drum type color laser printer, and includes a photoconductor drum 2, a charger 3, and a developing sleeve 5, each of which rotates clockwise in the device main body 1.
, transfer device 6 and cyan (C).

Magenta (M), Yellow (Y), Black (BL)
and a toner hopper 7 containing toner of different colors.
The photoreceptor drum unit 9 has four sets of photosensitive drum units 9, and is also provided with a laser oscillator, a polygon mirror 10, and a reflecting mirror 11 corresponding to each of these units 9, respectively. Further, a cassette 12 for storing transfer material and a paper feed roller 13 are provided below the apparatus main body 1, and further facing the four photoreceptor drum units 9, the paper is wound around a belt conveying roller 15. A conveyor belt 16 that rotates is disposed, and the conveyor belt 16 carries the transfer material by the belt=3.
- It is placed on the tray 16 and transported to each unit 9... A light reflection type seam sensor 17 consisting of a light emitting element and a light receiving element is provided below the conveyor belt 16, and a fixing device 20 equipped with a heat roller 19 is downstream of the conveyor belt 16. It is arranged. Further, a pair of discharge rollers 21 and a paper discharge tray 22 are provided adjacent to the fixing device 20. Then, a laser beam generated by a laser oscillator is scanned in the axial direction of the drum 2 via a reflecting mirror 11 by a polygon mirror 10 rotating at high speed onto the photosensitive drum 2 uniformly charged by the charge M3. In this way, a laser beam corresponding to a predetermined photoreceptor drum 2 is turned on or off depending on the pixel, and a latent image is formed on the photoreceptor drum 2, and then a latent image is formed on the photoreceptor drum 2.
As a result, toner of each predetermined color is attached, and the latent image is visualized.

Then, the transfer material stored in the cassette 12 is placed and conveyed on the conveyor belt 16, and each photoreceptor drum unit 9
. . , an image of a predetermined color corresponding to each pixel is transferred, the image is fixed by a fixing device 20, and a color copy is ejected onto an ejection tray 22.

On the other hand, the printer device M has a control section 25, which includes a microprocessor 26, a program storage section (hereinafter referred to as ROM) 27, as shown in detail in FIG.
, a data storage unit (hereinafter referred to as RAM) 29, an input/output port 30, a data bus 31, etc. By the way, the conveyor belt 16 is configured to be endless, and has a seam formed when it is configured to be endless, and in order to prevent the transfer material from being placed on the seam, the light at the seam is has a higher reflectance than other parts, and the light reflection type seam sensor 17 detects the seam.

The light receiving element of the seam detector 17 has an electronic circuit 1.
A photoelectric conversion section 7a is provided, and a voltage signal corresponding to the intensity of light received by the light receiving element is inputted from an analog input terminal of the microprocessor 26 of the control section. Furthermore, the control unit 25 is provided with a threshold value setting means 32, which is compared with the signal from the seam sensor 17, serves as a reference for determining the signal, and varies depending on the level of the signal. Set the threshold. Note that the threshold value setting means 32 is used during the initial process immediately after the power is turned on and when the conveyor belt 16
During driving, if a seam cannot be detected even after the time required for the conveyor belt 16 to make one revolution, the threshold value is determined and changed.

FIG. 3 shows a threshold value determination routine of the threshold value determination means 32, and this routine will be described in detail below along with the flowchart of FIG. 3. Note that the voltage signal converted by the photoelectric conversion section mentioned above and inputted from the analog input terminal of the microprocessor 26 (see FIG. 2) is converted into a digital quantity by the microprocessor 26, and the digital quantity is converted into a digital quantity by the light receiving element. There is an inversely proportional relationship in which the amount decreases as the amount increases, and the time measured by the timer is set at a time interval that can sample the light reception data at the seam of the conveyor belt 16 30 to 32 times while the conveyor belt 16 is being driven.

The first routine F1 sets addresses θ to 63 of the RAM 29 to FF (hexadecimal), and sets addresses 64 to 65 of the RAM 29 to 00. Next, the conveyor belt 16 is driven by the second routine F2. And the third routine F
3 converts the light intensity signal obtained from the electronic circuit 17a into a digital quantity. In the fourth routine, the third routine F
The data obtained in step 3 is stored in RAM 29 from 0 to 63 in descending order.
Relocate to street address. In this case, the data with the largest value will be discarded. In the fifth routine F5, the contents of address 64 in the RAM 29 are incremented, and in the sixth routine F, the above-mentioned clocking time is set, and the CPU waits for a clocking end interrupt from the timer. Then, when the timer ends, the third routine F3 is executed again. Note that the time obtained by multiplying the time counted by the timer once by the count value at address 64 in the RAM 29 is set to be the same as the time required for the conveyor belt 16 to make one revolution, and when branching to the seventh routine F7 The belt 16 has just made one revolution. Also, RAM29 O~
At address 63, data on the light intensity at the seam of the conveyor belt 16 and data on the portion where the light intensity is strongest outside the seam are stored in ascending order.

Then, in the seventh routine F7, the contents of address 0 of RAM 29 and the contents of address 1 of RAM 29 are compared to check the difference between these two data, and then each of the contents of address 1 and 2 up to the last address 63 is compared. Examine the differences between data. The data from the location with the largest difference to address 0 is the light intensity data at the joint of the conveyor belt 16,
Further, the area from the location with the largest difference to address 63 is the light intensity data of a portion other than the conveyor belt seam and most difficult to identify as a seam. Then, the intermediate value between the two pieces of data with the largest difference is used as the threshold for detecting the seam of the conveyor belt. Also, the eighth routine F
At step 8, it is checked whether the maximum difference obtained in the seventh routine F7 is larger than the specified value. If the difference is smaller than the specified value, it is determined that correction is impossible, and it is treated as an error. Further, in the ninth routine F9, the above-mentioned threshold value obtained in the seventh routine F7 is set at address 65 of the RAM 29.

Since the present embodiment has the above-described configuration, in the initial step after the power is turned on, the threshold setting means 32 sets a threshold that serves as a reference for determining the seam of the conveyor belt 16. Then, the seam sensor 17 detects that the conveyor belt 1
The control unit 2 outputs a voltage signal according to the received intensity of the reflected light from the control unit 6.
5, and the control section 25 compares the threshold value with the signal to detect a seam of the conveyor belt 16. Therefore, based on the detection of the seam, the control section 25 controls the conveyance timing of the conveyor belt 16 to convey the transfer material toward the transfer section 9 so that the transfer material does not ride on the seam.

In addition, the level of the output signal of the seam detection die 17 changes due to scattering of toner or the like or the influence of external light, making it impossible to detect the seam even after the time required for the conveyor belt 16 to make one revolution has elapsed. Then, the threshold value determination means 32 determines a new threshold value in accordance with the signal from the seam sensor 17 in place of the previous threshold value. Then, the control unit 25 compares the threshold value and the signal, and detects the seam of the conveyor belt 16 without error. Based on the detection of the seam, the control unit 25 controls the conveyor belt so that the transfer material does not get on the seam. The transfer material is transported by controlling the transport timing of 16.

(g) As described in detail, according to the present invention, there is provided a threshold value setting means for setting a threshold value that varies depending on the level of a signal from the detection means, and the threshold value setting means is used to detect fluctuations from the detection means. The optimal threshold value is set according to the signal to be detected, and the seam of the conveyor belt is detected by comparing the signal and the threshold value, thereby preventing contamination of the conveyor belt due to toner scattering, etc., and a decrease in the sensitivity of the seam sensor. Furthermore, the seam of the conveyor belt can be detected without error without being affected by external light.

Thereby, the transfer material can be controlled and conveyed so as not to be placed on the seam, so that a uniform transferred image can be obtained.

Furthermore, by knowing the change in the threshold value, it is also possible to detect contamination of the conveyor belt and the detection means.

[Brief explanation of drawings]

FIG. 1 is a side view schematically showing a printer device according to an embodiment of the present invention, FIG. 2 is a block diagram of its electronic circuit, and FIG.
The figure is a flowchart showing the threshold value determination routine of the threshold value determination means. M...printer device, 16...transport belt
, 17... optical sensor (seam sensor), 32...
Threshold setting means.

Claims (1)

[Claims] (1) Place the transfer material on a conveyor belt that has a seam, detect the seam of the conveyor belt with an optical sensor, place the transfer material on the conveyor belt avoiding the seam, and transfer it at the transfer unit. In the printer device, a threshold value setting means is provided for setting a threshold value by detecting a difference in light level from the surface of the conveyor belt based on the optical sensor, and the threshold value set by the threshold value setting means and A printer device characterized in that a seam of the conveyor belt is detected by comparing a signal from the optical sensor.