JP2004107030A - Recording medium detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording medium detector of simple constitution capable of finding accurately and stably thicknesses and kinds of various recording media different in quality during conveyance. <P>SOLUTION: This detector is provided with an ultrasonic oscillator 11 for emitting an ultrasonic wave toward the recording medium P conveyed in a conveying passage inside an image forming device, a transmitted ultrasonic wave receiver 12 for detecting the ultrasonic wave transmitted through the recording medium P, a reflected ultrasonic wave receiver 13 for detecting the ultrasonic wave reflected by the recording medium P, and a control means 16 for reading detection signals in the respective receivers to conduct computation processing. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a recording medium detection device that detects the thickness and type of a recording medium using the properties of ultrasonic waves in an image forming apparatus such as a copying machine and a printer (laser beam, dot impact, ink jet, etc.).
[0002]
[Prior art]
In an image forming apparatus using an electrophotographic method, the thickness of a recording medium greatly affects transfer characteristics and fixing characteristics. As the thickness of the recording medium increases, the transfer current needs to be increased for transfer, and the amount of heat needs to be increased for fixing. In other words, the types of recording media that can be transferred and fixed with a constant current and heat amount are limited. For this reason, the transfer current and the fixing temperature are adjusted by specifying the recording medium thickness by an external switch, or the fixing speed is adjusted to cope with the situation.
[0003]
However, the transfer process and the fixing process are processes that greatly affect the image quality of the copied image. In particular, in a full-color copying machine in which image quality is strict, many types of recording media are used. , High image quality cannot be maintained. Therefore, it is necessary to automatically detect the recording medium thickness by a recording medium thickness detection mechanism and set process conditions and the like according to the detected recording medium thickness.
[0004]
Conventional recording medium thickness detection mechanisms include those that detect the recording medium mechanically, such as by sandwiching the recording medium with an actuator, those that detect the recording medium electrically, by sandwiching the recording medium with electrodes, or those that use the property of the recording medium to light. Some of them are optically detected.
[0005]
Among the above-described conventional recording medium thickness detection mechanisms, those that mechanically detect the recording medium cannot be stably detected by the recording medium being transported because the recording medium is sandwiched between the actuators, and the mechanism becomes complicated. There is also a problem. In the case of electrical detection, the recording medium must be sandwiched between the electrodes, and has the same problem as that of the mechanical detection.
[0006]
In addition, the electrical characteristics of the recording medium do not always correspond to the thickness of the recording medium, and it is difficult to accurately detect the thickness of the recording medium. Further, in the mechanism for optically detecting the recording medium thickness described in Patent Document 1, the recording medium thickness is detected in a non-contact manner by measuring the transmission characteristics and reflection characteristics of the recording medium with respect to light. In recent years, the types of recording media have been diversified and increased, and in view of the current situation where reproduction recording media, colored recording media, etc. are flooding the market, it is not possible to accurately detect the thickness of the recording medium, and it occurs with time. There is also a problem that reliability is impaired due to dirt.
[0007]
The techniques described in Patent Literature 2 and Patent Literature 3 have a drawback in that it is required to stabilize the operation of a sensor or an amplifier with respect to a temperature change, and therefore, it becomes considerably expensive.
[0008]
In the reflection type ultrasonic receiver described in Patent Document 4, the moisture content and the like contained in the recording medium affect the reflection component of the ultrasonic wave, making it impossible to accurately measure the thickness of the recording medium. Similarly, even when a behavior variation such as floating inside occurs, the thickness of the recording medium cannot be accurately calculated.
[0009]
[Patent Document 1]
JP-A-6-331322 [Patent Document 2]
Japanese Patent Publication No. 7-84278 [Patent Document 3]
JP-A-9-34311 [Patent Document 4]
JP 2001-290315 A
[Problems to be solved by the invention]
Therefore, an object of the present invention is to solve the above-described problem in the conventional detection of the thickness of a recording medium. More specifically, it is an object of the present invention to provide a recording medium detection device having a simple configuration capable of stably and accurately determining the thickness and type of various recording media having different qualities during conveyance.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, an ultrasonic oscillator for irradiating an ultrasonic wave to a recording medium conveyed through a conveying path in an image forming apparatus and detecting an ultrasonic wave transmitted through the recording medium are provided. A recording medium detecting device including a transmitted ultrasonic receiver, a reflected ultrasonic receiver that detects ultrasonic waves reflected from a recording medium, and a control unit that fetches a detection signal of each receiver and performs arithmetic processing is the most important. Characteristics.
[0012]
According to a second aspect of the present invention, in the recording medium detecting apparatus according to the first aspect, the control means determines the thickness of the recording medium from the detection signal of the transmission ultrasonic receiver, and determines the thickness of the recording medium from the detection signal of the reflection ultrasonic receiver. The main feature is a recording medium detection device that determines the type of recording medium.
[0013]
According to a third aspect of the present invention, in the recording medium detecting apparatus according to the second aspect, the control unit changes the image forming condition of the image forming apparatus based on the determined thickness and type of the recording medium. Main features.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a functional block diagram of a recording medium detection device according to an embodiment of the present invention. The recording medium P is conveyed while being guided by the lower guide 1 and the upper guide 2.
[0015]
Units for detecting the thickness and type of the recording medium P include an ultrasonic oscillator 11, a transmitted ultrasonic receiver 12, a reflected ultrasonic receiver 13, an amplifier 14, a detector 15, a CPU 16, and a high-frequency oscillator 17.
[0016]
FIG. 2 is a characteristic diagram showing the relationship between the ultrasonic intensity measured by the transmission ultrasonic receiver 12 and the thickness of the recording medium, and FIG. 3 shows the relationship between the ultrasonic intensity measured by the reflection ultrasonic receiver 13 and the type of the recording medium. It is a characteristic diagram. As is clear from these characteristic diagrams, the transmission ultrasonic receiver 12 and the reflection ultrasonic receiver 13 can detect the thickness and type of the recording medium P.
[0017]
FIG. 4 is a flowchart of calculation (judgment) control of the thickness and type of the recording medium P by the CPU 16 and control of image forming condition setting. The operation of the present invention will be described with reference to FIGS.
[0018]
When the operator starts copying by the image forming apparatus (copier), the CPU 16 first transmits a reference ultrasonic wave from the ultrasonic oscillator 11 based on the high frequency from the high frequency oscillator 17 (S1), and initially sets the calibration. (S2). A transport device (not shown) of the image forming apparatus transports the recording medium P and guides the recording medium P to a detection position (S3).
[0019]
Next, the transmission intensity and the reflection intensity of the recording medium P are measured (S4). That is, when an ultrasonic wave is applied to the recording medium P from the ultrasonic oscillator 11, the transmitted light is detected by the transmitted ultrasonic receiver 12. Similarly, the reflected portion is detected by the reflected ultrasonic receiver 13.
[0020]
This detection data is amplified by the amplifier 14 and input to the CPU 16 via the detector 15. Then, the CPU 16 calculates the thickness and type of the recording medium from the input transmitted ultrasonic wave intensity and reflected ultrasonic wave intensity (S5). The calibration data program at this time is set in the CPU 16 in advance based on the characteristic diagrams of FIGS. In order to make the calculated value correspond to the actual thickness of the recording medium P, the thickness of the reference paper whose thickness is known is detected and calibrated in advance.
[0021]
Thereafter, the CPU 16 sets the transfer condition, the fixing condition, and the transport condition according to the calculated thickness of the recording medium P (S6), and controls the copying operation of the image forming apparatus (S7).
[0022]
As described above, in this recording medium detection device, the thickness and type of the recording medium P can be stably adjusted while the recording medium P is being conveyed by using the transmission and reflection intensity of ultrasonic waves without contacting the recording medium P. And accurately. Moreover, a simple configuration can be achieved. There is no particular restriction on the installation location of this apparatus in this image forming apparatus as long as it is upstream of the registration roller 3.
[0023]
【The invention's effect】
As described above, according to the present invention, an ultrasonic oscillator that irradiates an ultrasonic wave to a recording medium conveyed through a conveyance path in an image forming apparatus, and a transmitted ultrasonic wave reception that detects an ultrasonic wave transmitted through the recording medium Device, a reflected ultrasonic receiver for detecting ultrasonic waves reflected from the recording medium, and control means for taking in a detection signal of each receiver and performing arithmetic processing, wherein the control means detects a transmitted ultrasonic receiver. The thickness of the recording medium is determined from the signal, and the type of the recording medium is determined from the detection signal of the reflection ultrasonic receiver. Can be obtained stably and accurately.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of a recording medium detection device according to an embodiment of the present invention.
FIG. 2 is a characteristic diagram showing a relationship between an ultrasonic intensity measured by a transmission ultrasonic receiver and a recording medium thickness.
FIG. 3 is a characteristic diagram showing a relationship between an ultrasonic intensity measured by a reflected ultrasonic receiver and a recording medium type.
FIG. 4 is a flowchart of control for calculating the thickness and type of a recording medium and control for setting image forming conditions by a CPU.
[Explanation of symbols]
11 Ultrasonic oscillator 12 Transmitted ultrasonic receiver 13 Reflected ultrasonic receiver 16 CPU (control means)
P Recording medium

Claims (3)

An ultrasonic oscillator that irradiates an ultrasonic wave to a recording medium conveyed through a conveying path in an image forming apparatus, a transmitted ultrasonic receiver that detects an ultrasonic wave transmitted through the recording medium, and detects an ultrasonic wave reflected from the recording medium 1. A recording medium detection device, comprising: a reflected ultrasonic receiver that performs the processing; 2. The recording medium detecting device according to claim 1, wherein the control unit determines a thickness of the recording medium from a detection signal of the transmitted ultrasonic receiver and determines a type of the recording medium from a detection signal of the reflected ultrasonic receiver. A recording medium detection device characterized by the above-mentioned. 3. The recording medium detecting device according to claim 2, wherein the control unit changes the image forming condition of the image forming apparatus based on the determined thickness and type of the recording medium.

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