JP3011745B2 - Copier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of an electronic copying machine.

[Conventional technology]

Generally, this type of copier irradiates the original placed on the platen glass with the light of the light emitting lamp of the reading unit, and reflects the light on the drum or belt on the photoreceptor (OPC (organic photoreceptor)). It has a basic configuration in which an electrostatic latent image is formed, the electrostatic latent image is converted into a toner image in a developing unit, transferred onto recording paper, and thermally fixed in a fixing unit.

In this conventional copying machine, if the temperature of the platen glass rises above a predetermined temperature (75 ° C. in the following), there is a risk of causing physical and psychological harm to the user. In particular, for export products to the United States, this point is strictly regulated by UL standards and the like.

For this reason, in the conventional equipment, as a measure to prevent the platen glass temperature from heating, the temperature of the platen glass is actually measured by a temperature sensor, and when the temperature exceeds a predetermined value, the CPM value (number of copies per minute)
Down.

A predetermined CPM value is set according to the copy magnification.

Such a configuration was adopted.

[Problems to be solved by the invention]

The above-mentioned conventional copying machine using the temperature sensor of the above-described type causes an increase in man-hours, an increase in cost, and a complicated configuration of the apparatus due to the installation of the sensor.

When the CPM value is determined by the magnification, the processing speed may be reduced more than necessary even though the platen glass temperature does not rise, and the original performance of the apparatus cannot be exhibited.

There is such a problem.

In view of the above, the present invention does not use a special temperature sensor, and while maximizing the original performance of the device,
It is an object of the present invention to provide a copying machine in which the temperature of a platen glass does not exceed a predetermined temperature.

[Means for solving the problem]

In order to achieve the above object, a copying machine according to the present invention comprises an off-time detecting means for detecting an elapsed time after the operation is stopped, a paper size detecting unit for detecting a paper size of a recording paper, and a magnification detection for detecting a copying magnification. And a sheet number detecting unit for detecting the number of continuous copies, and during continuous processing, the elapsed time after the stoppage of operation detected by the off-time detecting unit, and the number of sheets detected by the paper size detecting unit. In accordance with the size, the copy magnification detected by the magnification detection unit, and the continuous copy number detected by the constant number detection unit, the number of processed sheets per unit time is switched during the processing. The number of sheets processed per unit time (CPM value) is set based on the elapsed time (off time) after stopping the operation, the paper size, the copy magnification, and the number of continuous copies.

(Principle of Off-Time Measurement) Prior to the description of the embodiment, a theoretical basis for a time measurement method based on heat radiation time characteristics used in the device of the present invention will be described.

First, as for the heat radiation time characteristic of the fixing roller surface temperature, assuming that the temperature inside the apparatus is constant regardless of the outside air temperature, time = T, initial temperature = 190 ° C, constant of proportionality = K, temperature inside the machine = 25 ° C, Assuming that the constant = η, the off time = τ, and the undetermined constant = C, T (τ) = Kexp (−τ / η) + C (1) can be approximately expressed. FIG. 4 is a heat radiation characteristic diagram of a temperature raising section (fixing section) of the apparatus of the present invention.

 Here, T (0) = K + C = 190 ° C. Since T (∞) = C = 25 ° C., the following is obtained: ∴K = T (0) −T (∞) = 190−25 = 165. That is, T (τ) = 165exp (−τ / η) +25 (1) ′. Next, when τ / η = 1, that is, when exp (−τ / η) = 0.368 T (τ) = 86 (° C.), τ = 10 (minutes). Good.

Here, considering the influence of the outside air temperature, the above equation (1) ′ is obtained.
T = 165exp (−τ / 10) + 25 + α (2) Here, α is a correction value indicating the influence of a temperature difference between the apparatus body and the outside air. As an approximate expression of the correction value _{α, α = (T R -25} ) (1-exp (-τ / 20)) where, T _R: and the use of room temperature.

In this case, when T (10) and T (20) are calculated for each room temperature where T _R = 10, 20, and 30 ° C. which is assumed as a normal temperature range, each time estimation error ΔT becomes ΔT (10) = Within ± 1 minute ΔT (20) = Within ± 2 minutes. For this reason, the error in estimating the off-time from the temperature of the temperature-raising section is sufficiently small at a maximum of about ± 10%, and it can be seen that time can be measured with accuracy that does not pose a problem in practical use. Further, it is possible to preliminarily estimate the influence of this kind of time measurement error on the process control, and to realize control with a margin in a range where the influence of the error does not affect.

(Measurement Principle of Platen Glass Temperature) The measurement principle of the platen glass temperature is the same as the above-described measurement principle of the off-time, and utilizes the heat radiation time characteristic of the platen glass.

That is, the heat radiation time characteristic of the platen glass shown in FIG.
Similar to the heat radiation time characteristic of the temperature raising part, the correspondence between the temperature and the off time is remarkable. Therefore, by recording this characteristic as a referable data map, the temperature can be estimated from the off-time obtained by the above-described method.

〔Example〕

Hereinafter, the present invention will be described based on an embodiment shown in the accompanying drawings.

1 is a block diagram showing the principle of an image forming apparatus according to the present invention, FIG. 2 is a block diagram showing the same, FIG. 3 is a flowchart showing main operations, and FIG. 4 is a principle diagram showing heat radiation characteristics of a fixing unit. FIG. 5 is a characteristic diagram of heat release over time of the platen glass,
FIG. 6 shows the temperature fluctuation characteristics when the CPM is changed according to the paper size and the magnification.

1 and 2, reference numeral 1 denotes a platen glass, and the platen glass 1 is provided on an upper surface of a main body 100 of the image forming apparatus. The platen glass 1 is for placing a copy original, is optically scanned by an original reading unit 2, and is configured to output image information of the original to a drawing unit 4.

Reference numeral 3 denotes an image generation unit. The image generation unit 3 can extract an image, a character, a graphic pattern, or the like from a predetermined storage device or a signal transmission device (not shown) and output it to the drawing unit 4. ing. The image generating unit 3 is used for creating an image not based on copying or adding a different type of image, character, or pattern to a copied image. Here, when the apparatus main body 100 of the present application is configured as a copying machine,
The image generator 3 may be omitted.

Reference numeral 5 denotes a latent image forming unit. The latent image forming unit 5 includes a photoreceptor K (drum or belt), and is configured to convert an image drawn by light rays from the drawing unit 4 into an electrostatic latent image. Have been.

Reference numeral 6 denotes a developing unit. The developing unit 6 is configured to attach toner to the electrostatic latent image of the photoconductor formed by the latent image forming unit 5 and convert the electrostatic latent image into a toner image. Then, the recording paper P onto which the toner image has been transferred is conveyed to the fixing unit 7, where the toner image is thermally fixed, and then discharged outside the apparatus.

Reference numeral 8 denotes a CPM setting unit, which is used to appropriately set the processing speed (the number of recording sheets processed in one minute) in accordance with the following conditions for preparing recording paper. is there. That is, the CPM value can be appropriately set according to the number of sheets to be continuously processed, the paper size of the recording paper, the magnification, the platen glass temperature, and the like.

Here, the number of continuous copies is determined by the number detection unit 10, the paper size of the recording paper is determined by the paper size detection unit (not shown), and the copy magnification is determined by the information detected by the magnification detection unit 9.
An input is made to the M setting unit 8.

In the CPM setting section 8, a plurality of CPM values are set,
According to the paper size, the magnification, and the number of sheets to be continuously processed, the optimum value can be selected even during the processing.

Fig. 6 shows how the platen glass temperature changes for "A4 200%, B4 200%".
By switching the CPM value during processing according to the paper size, magnification and the number of sheets continuously processed, it can be seen that the rising temperature is saturated within a range not exceeding 50 ° C. as shown by the dotted lines.

The platen glass temperature may be detected by providing a temperature sensor near the platen glass 1, but in the present embodiment, the platen glass temperature calculating unit 15 uses the fixing unit 7 as described in the principle description above. The platen glass temperature is calculated based on the off-time calculated from the heat radiation time characteristic and the predetermined heat radiation characteristic of the platen glass.

Reference numeral 12 denotes an off-time calculating unit. The off-time calculating unit 12 outputs an output of a temperature detecting unit 13 provided at a proper position of a heating unit in the fixing unit 7 (in this embodiment, at or near the surface of the heat fixing roller). An off-time detecting means capable of detecting an elapsed time after the operation is stopped is constituted by the information and a predetermined heat-dissipating aging characteristic of the temperature-raising section. That is, the off-time calculating unit 12 stores the heat radiation time characteristic of the heating unit in a memory in the form of a map, reversely deciphers the map from the output information of the temperature detecting unit 13, and calculates the off-time. It can be estimated. Then, based on the off time obtained by the calculation unit 12, it is determined whether or not to perform the charging process in the pre-processing unit 14, and the estimation of the platen glass temperature in the platen glass temperature calculation unit 15 is also performed. Note that the theoretical considerations regarding the heat radiation aging characteristics are as described above.

In the above-described embodiment, in the case of the copy mode, the original is placed on the platen glass 1, the light is emitted from the light emitting lamp of the original reading unit 2 to read the original, and the image information is transmitted to the drawing unit 4. On the other hand, in the CPM setting unit 8, the CPM value is appropriately determined according to each output of the paper size detection unit, the magnification detection unit 9, the number detection unit 10, the platen glass temperature calculation unit 15, and the like.

Next, the latent image forming unit 5 converts the optical image drawn on the photoconductor K into an electrostatic latent image, and then the developing unit 6 converts the latent image into a toner image. Further, the toner image is subjected to a heat fixing process in the fixing unit 7 and is discharged out of the apparatus. During this time,
The temperature of the fixing section 7 at an appropriate position is measured by the temperature detecting section 13, and the off time after the operation is stopped is calculated by the off time calculating section 12 from this temperature. Then, the platen glass temperature is calculated by the platen glass temperature calculator 15 based on the off time.

〔The invention's effect〕

As described above, the copying machine according to the present invention includes an off-time detecting unit that detects an elapsed time after the operation is stopped, a paper size detecting unit that detects a paper size of the recording paper, a magnification detecting unit that detects a copying magnification, A number detection unit that detects the number of continuous copies, and during continuous processing, the elapsed time after the operation is stopped detected by the off-time detection unit, the paper size detected by the paper size detection unit, In accordance with the copy magnification detected by the magnification detection unit and the continuous copy number detected by the fixed number detection unit, the number of sheets processed per unit time is switched during the processing. And the copy magnification and the number of continuous copies,
Since the CPM value can be reduced to the optimum value, the CPM value does not decrease unnecessarily, and it has the excellent effect of preventing the heating of the platen glass while maximizing the original performance of the device. It is.

[Brief description of the drawings]

1 is a block diagram showing the principle of an image forming apparatus according to the present invention, FIG. 2 is a block diagram showing the same, FIG. 3 is a flowchart showing main operations, and FIG. 4 is a principle diagram showing heat radiation characteristics of a fixing unit. FIG. 5 is a graph showing the heat radiation time characteristic of the platen glass, and FIG. 6 is a graph showing the temperature fluctuation characteristics when the CPM is changed according to the paper size and magnification. DESCRIPTION OF SYMBOLS 1 ... Platen glass 2 ... Document reading part 3 ... Image generating part 4 ... Drawing part 5 ... Latent image forming part 6 ... Developing part 7 ... Fixing part 8 ... CPM setting part 9 ... Magnification detection Unit 10: Number of sheets detecting unit 11: CVR adjusting unit 12: Off time calculating unit 13: Temperature detecting unit 14: Preprocessing unit 15: Platen glass temperature calculating unit K: Photoconductor P: Recording paper

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-219967 (JP, A) JP-A-2-114262 (JP, A) JP-A-1-296266 (JP, A) JP-A-2- 6977 (JP, A) JP-A-59-146075 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 21/00 370-540 G03G 21/14

Claims (1)

(57) [Claims] 1. An off-time detecting means for detecting an elapsed time after a stop of operation, a paper size detecting unit for detecting a paper size of a recording paper, a magnification detecting unit for detecting a copy magnification, and detecting the number of continuous copies. A number-of-sheets detecting unit, wherein during continuous processing, an elapsed time after the operation is stopped detected by the off-time detecting unit, a paper size detected by the paper size detecting unit, and a paper size detected by the magnification detecting unit. A copying machine that switches the number of sheets processed per unit time in the middle of processing in accordance with the determined copy magnification and the number of continuous copies detected by the constant number detection unit.