JPH03163951A - Dirt detector for picture read section - Google Patents

Abstract

PURPOSE:To surely detect the dirt of a picture read section by comparing a signal voltage of a picture signal resulting reading a white picture with a reference voltage and informing the presence of dirt when a signal voltage lower than the reference voltage exists. CONSTITUTION:In the case of detecting dirt, the read is implemented without any original. In this case, an image sensor 13 reads a white picture on the surface of a platen roller 11 through a platen glass 12 and outputs a picture signal Si. The picture signal Si is fed to a comparison arithmetic section 4 and the level of the signal voltage Ei is compared with a reference voltage Es fed from a reference voltage setting section 2. The comparison arithmetic section 4 applies waveform shaping while taking the reference voltage Es as a critical point and outputs a detection signal Sm. The detection signal Sm is fed to a notice section 5 and the notice section 5 informs the presence of dirt by the lighting of an alarm lamp and buzzering of an alarm buzzer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dirt detection device for an image reading section of an image scanner, facsimile, etc.

[Prior art and issues]

Generally, image scanners and facsimile machines are equipped with an image reading section that reads the image of a document and converts it into an electrical signal. It is composed of an image sensor etc. for reading.

Incidentally, the platen roller (platen sheet) and platen glass that constitute such an image reading section are likely to be contaminated by originals and the like. When dirt is attached, when the sensitivity of the image sensor is adjusted bit by bit, the dirt becomes a hindrance, making accurate adjustment impossible. As a result, the image quality deteriorates and, especially in the case of facsimile, a dirty image is sent as is to the destination.

2 However, in the past, cleaning was done exclusively during regular maintenance or by writing precautions in the instruction manual, leaving the cleaning to the operator, which in reality did not improve the effectiveness of cleaning. There was a problem.

It is an object of the present invention to provide a dirt detection device for an image reading section that solves the problems existing in the prior art.

[Means to solve the problem]

A dirt detection device 1 for an image reading section according to the present invention has a reference voltage E
The reference voltage setting section 2 for setting s compares the signal voltage Ei of the image signal Si of the white image read by the image reading section 3 with the reference voltage Es, and determines the signal voltage Ei lower than the reference voltage Es.
a comparison calculation unit 4 that outputs a detection signal Sm when
It is characterized by comprising a notification section 5 that notifies the existence of a fortune-telling based on the detection signal Sm. The image reading unit 3 includes a platen glass 12, a platen roller (platen sheet) 11 disposed on one side of the platen glass l2, and three image sensors l3 disposed on the other side of the platen glass l2. ,in this case,
In particular, it is desirable to color the surface of the platen roller (platen root) 11 white.

[For production]

According to the image reading unit dirt detection device 1 according to the present invention, a white level image signal Si is obtained by setting a white original in the image reading unit 3, and this signal voltage Ei is set to a reference voltage by the comparison calculation unit 4 in advance. Reference voltage E set by setting section 2
compared with s. As a result of the comparison, if there is a signal voltage Ei lower than the reference voltage Es, the comparison calculation unit 4 outputs the detection signal S.
m, and this detection signal Sm is supplied to the notification section 5,
Alerts the presence of dirt.

Note that if the surface of the platen roller (platen sheet) 11 in the image reading section 3 is colored white, stains can be detected without a white document set, that is, in a state where there is no document. By comparing the detection results of the angle (position) of 11 at multiple positions in the document feeding direction (main scanning direction), it is possible to determine whether it is dirt on the platen roller II (movable side) or the platen glass 12 ( It can be determined whether the dirt is on the fixed side).

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings.

First, the configuration of the dirt detection device 1 will be explained with reference to FIG.

3 is an image reading unit built into an image scanner, facsimile, etc., l1 is a platen roller (sometimes a platen sheet), 12 is a platen glass, and l3 is an image sensor. Platen roller (platen sheet) 1
The surface of 1 is colored white. Further, 14a and 14b, and 15a and 15b are transport rollers for transporting the document l6. As a result, the downward-facing document l6 to be transferred
passes between the platen roller 11 and the platen glass l2, and at this time, the image is read by the image sensor l3.

The image sensor 13 scans the image of the original document 16 and converts it into an image signal proportional to 5 image steps. The image signal is then supplied to the image signal processing system via the level correction circuit 17.

On the other hand, the dirt detection device I according to the present invention is connected to the output side of the image sensor l3.

The dirt detection device l includes a comparison calculation section 4. Comparison calculation section 4
One comparison human power terminal is connected to the output side of the image sensor l3, and the other comparison human power terminal is connected to the reference voltage setting section 2. Further, a notification section 5 is connected to the output side of the comparison operator 4.

Next, the function of the stain detection device 1 will be explained with reference to FIG. 2.

When detecting dirt, reading is performed without a document.

In this case, the image sensor l3 reads a white image on the surface of the platen roller l1 through the platen glass l2, and outputs an image signal Si having a waveform (for one line) shown in FIG. 2(a). The signal voltage of the image signal St is E
It becomes i. Note that if the color of the surface of the platen roller 11 is other than white, a white original may be set.

6 Now, assume that dirt is attached to an arbitrary position on the platen glass l2. In this case, a drop portion e corresponding to the dirt is generated in the waveform of the image signal St shown in FIG. 2(a).

In addition, in Fig. 2(a), the level correction possible range is M.
Then, by level-correcting the image signal Si in the level correction circuit I7, the correction signal Sw shown in FIG. 2(b) is obtained.
get. However, the drop portion e remains in a state where it cannot be corrected due to the correction limit, and is supplied as is to the image signal processing system.

On the other hand, the image signal S1 is supplied to the comparison calculation section 4, and the magnitude of the signal voltage Ei is compared with the base 4(-,yH pressure Es supplied from the reference voltage setting section 2. For example, as shown by the one-dot chain line in FIG. That is, the comparison calculation section 4 shapes the waveform using the reference voltage Es as a critical point as shown in FIG. As a result, the notification unit 5 notifies the presence of dirt by lighting an alarm lamp, generating an alarm buzzer, etc.

By the way, such stain detection is performed sequentially in the document feeding direction, but by comparing the detection results at a plurality of positions in the document feeding direction, it can be determined whether the stain is on the platen roller I1 or the platen glass I2. That is, when the drop portion e is detected from the image signal Si, if the state of the drop portion e is the same at multiple positions, it means that the platen glass 12 (fixed side) is dirty, and the drop portion e is
If the condition changes or disappears, the platen roller 11 (movable side) is dirty. This determination is performed using the detection data (
It can be easily determined by storing Ei) and comparing individual detection data.

Although the embodiments have been described in detail above, the present invention is not limited to these embodiments.

For example, although the comparison calculation section is connected before the level correction circuit, it may be connected after the level correction circuit.

Moreover, although the case where the reference voltage is set to an arbitrary value in advance is -8 is shown as an example, it may be set based on the average or variance of the detection signal. Furthermore, although an example is shown in which an image sensor is used as the image reading section, it can be implemented in the same way with other reading sensors or reading heads. This includes magnetically reading data from discs, video discs, etc. Further, in addition to an alarm, if a cleaning mechanism is incorporated in the notification section, a control circuit for operating the mechanism may be incorporated therein. Other changes may be made in the detailed circuit structure, etc., without departing from the gist of the present invention.

〔Effect of the invention〕

As described above, the image reading unit dirt detection device according to the present invention compares the signal voltage of the image signal obtained by reading a white image with the reference voltage, and outputs a detection signal when a signal voltage lower than the reference voltage is present. Since the presence of dirt is notified by the image reading section, dirt on the image reading section can be detected reliably. Further, since the presence of dirt is notified based on the detection, cleaning can be performed in a timely manner, and high quality image reading can always be maintained.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a dirt detection device for an image reading section according to the present invention. FIG. 2 is a signal waveform diagram of each part of the dirt detection device. In the drawing, 1: dirt detection device 3: image reading section 5: notification section 12: platen glass 2: reference voltage setting section 4: comparison calculation section 1l: platen roller I3: image sensor

Claims (1)

[Scope of Claims] [1] A reference voltage setting unit that sets a reference voltage and a signal voltage of an image signal of a white image read by an image reading unit are compared with the reference voltage, and a signal voltage lower than the reference voltage is present. What is claimed is: 1. A dirt detection device for an image reading unit, comprising: a comparison calculation unit that outputs a detection signal when the detection signal is detected; and a notification unit that reports the presence of dirt based on the detection signal. [2] Claim 1, wherein the image reading unit includes a platen glass, a platen roller or a platen sheet disposed on one side of the platen glass, and an image sensor disposed on the other side of the platen glass. The dirt detection device for the image reading section described above. [3] The dirt detection device for an image reading unit according to claim 2, wherein the surface of the platen roller or the platen sheet is colored white.