JPH0387887A - Fixing device - Google Patents

Abstract

PURPOSE:To exactly detect the volume of oil by limiting the floating region of the float of an oil amt. detecting means to a range where the float does not come into contact with an oil case. CONSTITUTION:The floating region of the float is so limited that the float 31 of a detecting means 30 does not come into contact with the bottom part 7a of an oil pan 7 even when a liquid level falls and oil replenishment is started. The means 30 is, therefore, so constituted that its lever 50 collides against a stopper 200 to provide a spacing X even when the oil runs out completely. The contact part 51 of the means 30 comes into contact with the stopper 200 when the oil level rises to attain a set level. The rotation thereof is then limited and the spacing Y is provided between the means 30 and the wall surface 7b of the oil pan 7. The non-operation of the float by the viscosity of the oil is prevented in this way and the exact volume of the oil is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fixing device that applies release oil to a fixing rotating body.

[Conventional and Background Art] Conventionally, in electrophotographic copying machines, electrostatic printers, etc., a toner image formed on a photoreceptor as a latent image carrier is transferred onto a recording material by a fixing roller that applies heat or pressure. The image is fixed by a fixing device having a. In this type of fixing device, in order to prevent the toner image from being offset to the fixing roller and to make it possible to easily peel off the transfer paper from the fixing roller, the fixing roller is coated with 100 to 500
It is common practice to apply a mold release oil such as silicone oil having a viscosity of about CS.

As a means for applying such oil, a first conventional example shown in FIG. 1 is known. In the figure, silicone oil 1 contained in an oil tank 2 is sucked up by a pump 3 through a supply vibrator 4 and sent to a nozzle 6 via a supply vibrator 5. Below the nozzle 6 is an oil pan (a case for storing oil).
A coating felt 10 (hereinafter referred to as an oil pan) 7 is provided, and a lower portion of a coating felt 10 serving as a coating member whose upper portion is in contact with the outer circumferential surface of the fixing roller 8 is immersed in the oil pan 7 by a support plate 11. The oil inside is sucked up by capillary action and supplied to the fixing roller 8. Fixing roller 8
A pressure roller is rotating in pressure contact with the fixing roller 8, and a web 12 for cleaning dirt from the fixing roller 8 is also in contact with the fixing roller 8. The oil pan 7 is partitioned by a partition plate 13 into a large chamber 14 and a small chamber 15 in which the coated felt 10 is immersed.

The oil 1 in the large chamber 14 dripped from the supply vibrator 5 through the nozzle 6 overflows the partition plate 13 and flows into the small chamber 15. A discharge port 16 is provided at the bottom of the small chamber 15 so that the oil 1 in the small chamber 15 can be returned to the oil tank 2, so that the oil 1 is circulated within the fixing device.

However, in a fixing device having the oil circulation mechanism described above inside the fixing device, even when the oil pan 7 is sufficiently filled with oil 1, the pump 3 always continues to supply oil 1, so the frequency of oil 1 circulation increases and the oil There was a problem that the lifespan of 1 was shortened.

Also, since the large chamber 14 near the heated fixing roller 8 is always full of oil 1, the fixing roller 8
There is also a problem in that the evaporation rate of the oil 1 in the large chamber 14 increases due to the heat, resulting in an increase in the amount of oil 1 consumed.

Therefore, in order to solve the above problem, a technique as shown in FIG. 2 can be considered. In FIG. 2, reference numeral 30 is an oil amount detection means equipped with a float 31 as a floating member provided in the fixing device, and rotates about the support shaft 32 as the liquid level of the oil 1 in the large chamber 14 rises. When the liquid level reaches a certain set level, the photosensor 33 serving as the detection means is shut off. Then, a signal to stop the supply is sent to the pump 3, and the supply of the oil 1 by the pump 3 to the oil pan 7 is stopped.

On the other hand, when the oil 1 continues to be supplied to the fixing roller 8 by the coating felt 10 and the liquid level of the oil 1 in the oil pan 7 falls below the set value, a supply start signal is sent from the photosensor 32 to the pump 3. Then, the oil 1 is supplied to the oil pan 7 again.

As explained above, the oil amount detection means 3 is installed in the fixing device.
By providing 0, it is possible to suppress the supply and circulation of oil 1 more than necessary, and the amount of oil 1 in the oil pan 7 can always be maintained at an optimal amount.

[Problems to be Solved by the Invention] However, the oil amount detection using the floating member as described above also has the following problems.

As shown in FIG. 3, when there is no oil in the oil pan 7, the float 31 is prevented from rotating by the bottom 7a of the oil pan 7 and is located on the top surface of the bottom 7a. In this state, since the photosensor 33 is open, an oil replenishment signal is sent to the pump 3 and oil is supplied. However, since silicone oil has viscosity, it is difficult for the oil to enter the space 800 between the float 31 and the bottom 7a, as shown in FIG.

Therefore, even though there is sufficient liquid level height, float 3
1 does not move, and as a result, the photo sensor 33 remains open and cannot detect the liquid level, which may cause oil to overflow from the oil pan. Also, as shown in Figure 5, oil 1
As mentioned above, the photo sensor 33 is cut off and the supply of oil 1 from the pump 3 is stopped when the liquid level rises and the float 31 rises.

However, as shown in Figures 5 and 6, the float 31 and the wall surface 7b of the oil pan 7 are close to each other or in contact (100), so the oil level drops as shown in Figure 6, and oil needs to be supplied. Even in this case, the float 31 and the wall surface 7b stick together due to the viscosity of the oil, and the float does not operate, and the liquid level cannot be detected in this case as well.

These problems are more noticeable when the viscosity of the oil is high.
This is particularly likely to occur when the viscosity at room temperature is 80 cs or more.

[Means for Solving the Problems] The present invention, which solves the above-mentioned problems, includes a fixing rotary body, an oil case storing mold release oil to be applied to the fixing rotary body, and an amount of oil in the oil case. In the fixing device having a detection means for detecting the
It has a floating member floating in oil and a detection unit that is activated depending on the floating state of the floating member, and the floating area of the floating member is limited so that the floating member does not come into contact with the oil case. It is something to do.

[Embodiments of the invention] Embodiments of the present invention will be described below based on the drawings.

FIG. 7, FIG. 8, and FIG. 9 are simplified cross-sectional views showing embodiments of the present invention.

Reference numeral 30 denotes an oil amount detection means with a float 31 provided in the fixing device, which rotates around the support shaft 32 as the liquid level of the oil 1 in the large chamber 14 rises, until the liquid level reaches a set level. When this happens, the photosensor 33 serving as the detection means is shut off. (FIG. 8) Then, as described above, a supply stop signal is sent to the pump 3, and the supply of oil 1 by the pump 3 to the oil puncture is stopped. These operations are the same as those of the device shown in FIG.

Here, as shown in FIG. 7, even if the liquid level is at the bottom and oil replenishment is started, the float 31 and oil pan 7
The floating area of the float 31 is limited so that a clearance X is provided between the bottom 7a of the float 31 and the lever 50 of the detection means 30 is fixed against the rotation of the arrow 201 even when the oil is completely empty. Stopper 2 placed in
It is configured such that the gap X is provided per 00. Furthermore, as shown in FIG. 8, when the oil level rises and reaches a set level, a gap Y is also provided between the detection means 30 and the wall surface 7b of the oil pan 7, and the oil pan rotates in the direction of arrow 202 due to some action. Even if the abutment part 51 of the detection means
hits the stopper 200 and its rotation is restricted, but even at this time it is configured so that a clearance Y is provided.

Here, it is preferable that the gaps X and Y are 0.5 mm or more.

FIGS. 10 and 11 are diagrams showing another embodiment of the present invention.

As in the previous embodiment, the detection means 30 is provided with a float 31 and a guide groove 500. A guide shaft 70 is fitted in this guide groove and guides the detection means 30 in the direction of arrow 520. Now, as shown in FIG. 32, when the liquid level falls, the photointerrupter of the detection means 33 is opened, as described above, and oil supply is started. At this time, there is a gap W between the float 31 and the bottom of the oil pan 7, and a gap Z between the float 31 and the wall surface 7a. Next, the liquid level rises and the detection means 30
Even when the detection means 33 is blocked by the oil pan 7 and the detection means 30, a gap Z is provided between the oil pan 7 and the detection means 30, as described above.

Furthermore, even if the detection means 30 attempts to move up and down (in the direction of arrow 520) due to some action, the edge of the guide groove (500a
, b) are connected to the guide shaft, and the contact position is restricted, but even at this time, the structure is such that clearances W and Z are provided.

It is preferable that the gaps W and Z are also 0.5 mm or more as described above.

As described above, in this embodiment, the guide groove limits the floating area of the float 31.

[Effects of the Invention] As described above, according to the present invention, changes in the oil amount can be accurately detected by the accurate operation of the detection means, so that insufficient oil amount and overflow can be prevented.

Therefore, even when oil is used in circulation, it is possible to reduce the frequency of oil circulation, extend the life of the oil, and improve consumption efficiency.

Furthermore, the amount of oil applied to the fixing rotating body is always maintained at an optimum level, making it possible to maintain good images.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional fixing device, FIG. 2 is a sectional view showing a fixing device which is the background of the present invention, and FIGS. 3 to 6 show points of interest of the device shown in FIG. 7 and 8 are sectional views of the vicinity of the oil pan of the apparatus according to the embodiment of the present invention. FIG. 9 is a sectional view of the fixing device of the embodiment of the present invention. FIGS. 10 and 11 are sectional views of the vicinity of an oil pan according to another embodiment of the present invention. 7... Oil pan (oil pan) 8... Fixing roller 21... Detecting means (photo sensor) 22... Floating member (float) 23... Detecting plate 24... Supporting member 25...・Support shaft? 0/

Claims (3)

[Claims] (1) In a fixing device having a fixing rotary body, an oil case storing mold release oil to be applied to the fixing rotary body, and a detection means for detecting the amount of oil in the oil case, the detection means is , comprising a floating member floating in oil and a detection unit activated by the floating state of the floating member, and characterized in that the floating area of the floating member is limited so that the floating member does not come into contact with the oil case. fixing device. (2) The fixing device according to claim 1, wherein the release oil has a viscosity of 80 cs or more at room temperature. (3) The fixing device according to claim 1 or 2, wherein a gap of 0.5 mm or more exists at a position where the floating member is closest to the oil case.