JP3011744B2 - 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 apparatus, as a measure for preventing the heating of the platen glass temperature, the temperature of the platen glass is actually measured by a temperature sensor, and when the temperature exceeds a predetermined value, the CPM value (the number of copies per minute) is lowered (special). Kai 61-619967, JP 61-261
753).

During continuous copying, the lighting time of the second and subsequent light emitting lamps is shortened (JP-A-58-111958).

Such a configuration was adopted.

[Problems to be solved by the invention]

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

When the lighting time of the second and subsequent light emitting lamps is shortened, the processing speed is reduced more than necessary, and the original performance of the apparatus cannot be exhibited.

There is such a problem.

This invention maximizes the original performance of the device,
It is an object of the present invention to provide a copying machine that can prevent overheating of the platen glass.

[Means for solving the problem]

In order to achieve the above object, a copying machine according to the present invention includes a paper size detection unit for detecting a paper size of a recording paper, a magnification detection unit for detecting a copy magnification, and a paper size detected by the paper size detection unit. Based on the copy magnification detected by the magnification detection unit, a setting unit that sets the number of sheets processed per unit time and a threshold value, at the time of continuous copying,
When the number of continuous copies reaches the threshold value set by the setting unit, the number of sheets processed per unit time is changed to the number of sheets processed per unit time set by the setting unit. Based on the magnification, the number of sheets processed per unit time (CPM value) and a threshold value are set, and when the number of continuous copies reaches the threshold value, the CPM value is changed to the set value. is there.

(Principle of Off-Time Measurement) Prior to the description of the embodiment, a theoretical basis of a time measurement method using the heat radiation time characteristic used in the copying machine of the present application 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.

〔Example〕

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

FIG. 1 is a principle configuration diagram showing a configuration of a copying machine of the present invention,
2 is a block diagram, FIG. 3 is a flowchart showing main operations, FIG. 4 is a heat radiation characteristic diagram of a fixing unit, and FIG. 5 is a platen glass temperature by CPM control for A4 • 200% and B200% originals. FIG.

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 apparatus of the present invention. The platen glass 1 is for placing a copy original, is optically scanned by a light emitting lamp of the original reading unit 2, and is configured to output image information of the original to the 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 3 into an electrostatic latent image. Have been.

Reference numeral 6 denotes a developing unit. The original unit 6 is configured so that toner adheres to the electrostatic latent image of the photoconductor formed by the latent image forming unit 5 and can be converted into a toner image. Then, the recording paper P 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 continuous copies, the paper size of the recording paper, the copy magnification, the effective heat value = (paper size) × (copy magnification), and the like.

Here, the number of continuous copies is detected by the number detection unit 10, the paper size of the recording paper is detected by the paper size detection unit (not shown), and the copy magnification is detected by the magnification detection unit 9, respectively. The calculation unit 20 is configured to calculate (paper size) × (copy magnification).

Reference numeral 8 denotes a CPM setting unit, in which a plurality of thresholds of CPM values are set in the CPM setting unit 8 so that the optimum value can be appropriately selected during continuous copying. That is, continuous copying is first started at the maximum CPM value (maximum processing speed), and when the number of continuous copies reaches a predetermined threshold level, the CPM value is reduced to a CPM value corresponding to the paper size of the recording paper and the copying magnification. It has become. However, the timing (threshold) of this CPM down is appropriately delayed according to the value of (paper size) × (copy magnification) calculated by the effective heating value calculation unit 20, and the processing performance of the apparatus is not excessively suppressed. It has been adjusted as follows.

FIG. 5 shows the relationship between the magnification, the paper size, and the number of sheets continuously processed.
See “A4 ・ 20” for how the platen glass temperature changes.
0%, B4 · 200% ”. As is clear from this figure, by appropriately switching the CPM value while referring to the value of (paper size) × (copy magnification), the saturation of the platen glass temperature rise can be controlled to 50 ° C. or less as shown by the dotted line. .

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). It is configured such that the elapsed time after the operation is stopped (= the off-time) can be calculated based on the information and the heat-dissipation aging characteristics of the heating unit determined in advance. That is, the off-time calculating unit 12
Is configured to store the heat radiation aging characteristics of the temperature raising unit in a memory in a map format, and to reversely decipher the map from output information of the temperature detection unit 13 to estimate the off time. Then, based on the off time obtained by the calculation unit 12,
It is also possible to estimate the temperature of the platen glass. The theoretical consideration regarding the principle of the time measurement method based on the heat radiation time characteristic is as described above.

In the above embodiment, the light of the light emitting lamp is irradiated on the original on which the original is placed on the platen glass 1, and the reflected light is transmitted as image information to the drawing unit 4 via the original reading unit 2. On the other hand, in the CPM setting unit 8, the CPM value is appropriately determined according to each output of the magnification detection unit 9, the continuous copy number detection unit 10, and the effective heating value calculation unit 11.

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 detecting section 13 measures the temperature of the fixing section 7 at an appropriate position. The OFF time after the operation is stopped is calculated by the OFF time calculating section 12 from this temperature. Then, based on this off time, the preprocessing unit 14 determines whether or not to perform the charging process on the photoconductor K, and the platen glass temperature calculation unit 15 can calculate the platen glass temperature.

〔The invention's effect〕

As described above, the present invention sets the number of processed sheets per unit time and the threshold based on the detected paper size and the copy magnification, and when the number of continuous copies reaches the threshold,
It changes to the set CPM value.

Therefore, the present invention has an excellent effect that the platen glass can be prevented from being heated while the original performance of the apparatus is maximized without unnecessarily reducing the number of sheets processed per unit time.

[Brief description of the drawings]

1 is a block diagram showing the principle of the construction of a copying machine according to the present invention, FIG. 2 is a block diagram showing the same, FIG. 3 is a flowchart showing main operations, FIG. Is
FIG. 9 is a diagram illustrating a change in platen glass temperature by CPM control for A4 · 200% and B200% originals. DESCRIPTION OF SYMBOLS 1 ... Platen glass 2 ... Document reading part 4 ... Drawing part 5 ... Latent image forming part 6 ... Developing part 7 ... Fixing part 8 ... CPM setting part 9 ... Magnification detecting part 10 ... Number detection Unit 11 CVR adjustment unit 12 Off-time calculation unit 13 Temperature detection unit 14 Preprocessing unit K Photoconductor P Recording paper

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

Claims (1)

(57) [Claims] A paper size detection unit for detecting a paper size of a recording paper; a magnification detection unit for detecting a copy magnification; a paper size detected by the paper size detection unit; and a copy detected by the magnification detection unit. A setting unit for setting the number of sheets to be processed per unit time and a threshold based on the magnification, and when the number of continuous copies reaches the threshold set in the setting unit during continuous copying A copying machine configured to change the number of sheets processed per unit time set by the setting unit.