Modern Xiaomi, Redmi and POCO smartphones are equipped with advanced interface control systems that are designed to make life easier for the user during calls. The standard behavior of the device is to automatically turn off the display when you bring the phone to your ear, which prevents accidental pressing of the cheek or ear, but many owners face a situation where the screen continues to burn, preventing normal communication, or, conversely, goes out too early, not allowing you to press the button of the loud speaker.
Understanding how to lock the screen when speaking in Xiaomi is not only necessary for comfort, but also for saving battery power, since a constantly running display consumes a lot of energy. In the MIUI or HyperOS operating system, this process is responsible for a set of software algorithms and physical sensors that sometimes require manual adjustment. Below we will discuss in detail the mechanics of the sensors and how to control the lock.
In some cases, users need to do the opposite: make sure that the screen does not go out, for example, when watching a video during a call or using a video link. Xiaomi’s flexibility of settings allows you to adapt the behavior of the smartphone to your individual habits, whether it is a classic voice call or communication through messengers. Let’s look at the basic mechanisms of screen control.
The principle of operation of the proximity sensor in MIUI
The fundamental element of the locking system is the proximity sensor, which is physically located at the top of the smartphone body, often hidden under the display frame or in the speaker notch. This sensor emits invisible infrared radiation and analyzes its reflection from objects. When you bring the phone to your head, the infrared beam reflects faster, and the system receives a signal that the object is in close proximity, triggering a command to turn off the backlight.
In Xiaomi smartphones, the software processes data from the sensor at a high frequency, but sensitivity can vary depending on the model. For example, in the budget Redmi series, the sensor may be less accurate compared to the flagships of the Mi or Xiaomi Pro series. If the sensor is contaminated or closed with a dense case, the system may not receive the correct signal and the screen will remain on.
Technical Features of Virtual Sensors
It's important to note that sensor calibration is a process that the system can perform automatically when booting, but sometimes requires user intervention. If you notice that the phone is responding to a hand approaching with a delay, this may indicate a software failure in processing sensor data, in which case it helps to reboot the device or reset the sensor settings through the engineering menu.
Set up a lock through the standard menu
For most users, it is enough to check the basic telephony settings to ensure that the screen works correctly. In the MIUI shell, the path to these parameters is standardized, although the names of points may differ slightly in different versions of the firmware. To manage locking, you need to go to the Phone application and open the menu of additional options.
In the list that opens, you should select Settings, and then find the Incoming Calls section. This is where the key switch for the display's approach response is located. If the Approximation Sensor is active, the screen will go out automatically. If you want it to burn constantly (for example, for people with visual impairments or for specific tasks), this switch must be deactivated.
☑️ Checking the call settings
It’s worth considering that in some updated versions of HyperOS, the logic of the work may have changed, and there may not be a separate switch, since the system relies on intelligent algorithms. In this case, if the screen does not go out, the problem may lie not in the settings, but in the application conflict. System permissions for the Phone application also play a role: make sure that it has access to the device’s sensors.
⚠️ Attention: If you turn off the proximity sensor, the screen will burn constantly during a conversation, which can lead to accidental cheek pressing, a call reset or a speaker switch, which will put the interlocutor in an awkward position.
Use of the Engineering Menu for Calibration
If the standard settings don’t work and the screen is chaotic, you’ll need a deeper diagnosis through the engineering menu, which is a hidden partition of the Android system that is available on Xiaomi devices through a special code, and you’ll need to open the caller and type in the ##6484## combination to open the CIT (Customer Information Test) menu.
You'll need to look for a point on the test list that's associated with the Proximity Sensor, and if you click on it, you'll see the current readings of the sensor, and if you hold your hand to the top of the screen and remove it, the values should vary (usually from 0.0 to 5.0 or from 0 to 1 depending on the sensor type), and if the values don't change, the sensor is physically or software-locked.
To reset the calibration, the Calibrate or Check button is often available on the same menu. When you press it, follow the instructions on the screen: you usually close the sensor with your hand and then open it. Once you have successfully calibrated, the system will retain the new reference values, which often solves the problem when the screen does not go out even when the phone is tightly attached to the ear.
Influence of protective glasses and covers
One of the most common reasons for the screen locking to work is accessories. Cheap black-framed security glasses can block the sensor’s operation, especially if they are unevenly glued or have a thick layer of glue at the edges, in which case the sensor “thinks” that the object (glass) is already nearby, and either constantly keeps the screen off or, conversely, ignores the real approximation.
Tight leather or silicone bookcases can also cause interference if they are not designed to cut out under the top of the screen. Magnetic latches of such cases sometimes affect the operation of the magnetometer, which is used in conjunction with the proximity sensor to determine the position of the smartphone in space. Removing the case is the first step in diagnosing the problem.
If you use a hydrogel film, it's generally not interfering with the sensor, because it's transparent to infrared radiation. However, if the film has greasy spots or contamination in the sensor area, it can scatter the signal. Regularly rubbing the top of the smartphone with microfiber helps keep the locking system running smoothly.
Comparison of screen behavior in different applications
The behavior of the screen during a conversation can vary depending on which application is used for communication. The standard set of Google Phone or MIUI Dialer takes priority in the system and receives data from the sensor directly. Messengers such as WhatsApp, Telegram or Viber work through the VoIP audio stream and can interpret the system signals differently.
Below is a table showing the differences in screen lock operation depending on the type of application and the state of settings:
| Annex | Sensor response | Possibility of disconnection | Dependence on OS version |
|---|---|---|---|
| System call. | Instant. | Yes (via settings) | Tall. |
| WhatsApp / Viber | Detained | No (depending on OS) | Medium |
| Telegram | Variable | No. | Low. |
| Skype / Zoom | It often doesn't go out. | No. | Low. |
Messengers often don’t have a separate screen lock setting, as they rely on the Android event handler. If WhatsApp doesn’t go out and everything works in a regular call, the problem may be optimizing the app itself for your version of MIUI. In such cases, cleaning the app cache or reinstalling it helps.
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If the screen goes out too early during a video call in the messenger, try turning the phone into horizontal mode – this often turns off the proximity sensor by software, as it is believed that the phone is lying on the table.
Solving problems with the constant inclusion of the screen
When the screen is constantly on fire, even when the phone is lying on the table during a conversation, it can cause quick discharge and random actions. If calibration and removal of the case did not help, it may be that the system has accumulated software debris or conflict with third-party applications that have access to call management (for example, number detectors or call records).
Try resetting telephony-related apps. Go to Settings → Apps → All apps, find Phone, Call Management and Contacts. From each of them, select Clear → All data. Don't worry, contacts won't be deleted, they're stored in a separate storage or Google account, but the call settings will go back to factory settings.
⚠️ Warning: Third-party call recording applications (Cube Recorder, Call Recorder) often intercept audio stream control and may block the proximity sensor.
In extreme cases, if the problem occurs after a firmware update, it can be a bug of a specific version of MIUI. In such cases, users often wait for a patch from the manufacturer or use third-party utilities to control the sensors, although the latter require Root rights, which is not recommended for ordinary users for security reasons.
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Comprehensive verification includes: removal of the case, cleaning the sensor area, calibration through the engineering menu and checking conflicting applications.